48FK,JK034-074
50FK,FY,JK,JY034-104
Variable-Air Volume Rooftop Units
Controls Operation,
and Troubleshooting
CONTENTS
Page
Page
• NIGHT SETBACK CONTROL
SAFETY CONSIDERATIONS . . . . . . . . . . . . . . . . . . . . . 2
• UNIT SUPPLY AIR SET POINT ADJUSTMENT
• DEMAND UNIT (1-STAGE OR 2-STAGE)
GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-13
Rooftop Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
VAV Control System . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Processor Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
• P1 — SUPPLY-AIR SET POINT
• SUPPLY DUCT PRESSURE SET POINT ADJUSTMENT
• EXTERNAL ALARM SIGNAL
• REMOTE ECONOMIZER CONTROL
Smoke Control Modes . . . . . . . . . . . . . . . . . . . . . . . . . 21
• FIRE SHUTDOWN MODE
• P2 — ECONOMIZER POSITION
• P3 — RESET LIMIT
• PRESSURIZATION MODE
• P4 — DEMAND LIMIT
• EVACUATION MODE
• P5 — ECONOMIZER MINIMUM POSITION
• P6 — WARM-UP SET POINT
• SMOKE PURGE MODE
• INSTALLATION
• P7 — SASP RESET TEMPERATURE
• PROCESSOR BOARD OUTPUTS
• CONFIGURATION
• OPERATING SEQUENCE
• CONFIGURATION HEADER AND DIP SWITCH
ASSEMBLY
Air Pressure Tubing . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
• INLET GUIDE VANES
Relay Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Display Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Thermistors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
• T1 — SUPPLY-AIR TEMPERATURE THERMISTOR
• T2 — RETURN-AIR TEMPERATURE THERMISTOR
• T3 — SATURATED CONDENSING TEMPERATURE,
CIRCUIT 1
• VARIABLE FREQUENCY DRIVE
• MODULATING POWER EXHAUST
START-UP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25-30
Initial Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Configuration Header . . . . . . . . . . . . . . . . . . . . . . . . . 26
DIP Switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Adjusting Set Points . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Potentiometers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Supply Fan Control with IGV Option . . . . . . . . . . . . . 28
Supply Fan Control with VFD Option . . . . . . . . . . . . 28
Modulating Power Exhaust
• T4 — SATURATED CONDENSING TEMPERATURE,
CIRCUIT 2
• T10 — RESET TEMPERATURE
Compressor Operation . . . . . . . . . . . . . . . . . . . . . . . . . 7
• CONTROL RELAY (CR)
Accessory Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
• P3 — RESET LIMIT
• P5 — ECONOMIZER MINIMUM POSITION
• P6 — MORNING WARM-UP TEMPERATURE
Single-Step Demand Unit . . . . . . . . . . . . . . . . . . . . . . . 7
Demand Limit Control Module (DLCM) . . . . . . . . . . . . 7
Economizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
• ENTHALPY CONTROL
(Option or Accessory) . . . . . . . . . . . . . . . . . . . . . . . 30
START UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31-34
Quick Test Program . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
OPERATING INFORMATION . . . . . . . . . . . . . . . . . . . 34-43
Digital Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
• CODES 0 THROUGH 8, CAPACITY STEPS
• CODES 20 THROUGH 30 AND 88, OPERATIONAL
STATUS
• DIFFERENTIAL ENTHALPY
• CODES 51 THROUGH 87, DIAGNOSTIC
INFORMATION
Operating Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . 35
• SIZE 034, 038 AND 048-088 UNITS
• SIZE 044 UNITS
• SIZE 104 UNITS
Head Pressure Control . . . . . . . . . . . . . . . . . . . . . . . . 36
Supply Fan Control with IGV . . . . . . . . . . . . . . . . . . . 38
Supply Fan Control with VFD . . . . . . . . . . . . . . . . . . . 38
Modulating Power Exhaust (Option or
Accessory Except FY,JY Units) . . . . . . . . . . . . . . . 38
Unit Staging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Variable Frequency Drive (VFD) . . . . . . . . . . . . . . . . . 12
Temperature Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
CONTROLS INSTALLATION . . . . . . . . . . . . . . . . . . . 13-25
Control Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
• NIGHT SETBACK THERMOSTAT
• SPACE TEMPERATURE RESET ACCESSORY
(50DJ900021)
Space Temperature Reset . . . . . . . . . . . . . . . . . . . . . . 13
• INSTALLATION
• CONFIGURATION
• OPERATING SEQUENCE
Demand Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
• SINGLE-STEP DEMAND LIMIT
• TWO-STEP DEMAND LIMIT
TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . 44-57
Checking Display Codes . . . . . . . . . . . . . . . . . . . . . . . 44
Complete Unit Stoppage . . . . . . . . . . . . . . . . . . . . . . . 44
Single Circuit Stoppage . . . . . . . . . . . . . . . . . . . . . . . 44
Restart Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Diagnostic Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
• CODES 51, 52, 55, 56: COMPRESSOR FAILURE
• INSTALLATION
• CONFIGURATION
• OPERATING SEQUENCE
Control From Remote Building Management
System (BMS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
• OCCUPIED/UNOCCUPIED
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
Book 1 PC 111 Catalog No. 534-716 Printed in U.S.A. Form 48/50F,J-1T Pg 1 4-99 Replaces: 48/50D,F,J-1T
Tab 1a 1b
1
LEGEND
*EPROM HT204485-1-XX where ‘‘XX’’ is the current revision
number.
DIP
EPROM
EXV
—
—
—
Dual In-Line Package
Erasable, Programmable Read-Only Memory
Electronic Expansion Valve
NOTE: Processor Board is positioned in unit with J3 and J10 con-
nections at the bottom.
Do not remove label covering EPROM. Removal causes pro-
gram to be erased.
Fig. 1 — Processor Board
Several temperature inputs are connected to the proces-
sor. There are either 4 or 5 thermistors (depending on the
field-installed accessories) which input temperature data
into the processor through pin terminal connector J1. See
Table 1 and Fig. 2.
In addition to the unit status switch inputs, the processor
board also accepts inputs from several potentiometers. These
potentiometers control various operational characteristics of
the system. Inputs are received by the processor through pin
terminal connector J3. See Fig. 4.
Several status switches are also monitored. These switches
are connected to the processor at pin terminal connector J2.
See Fig. 3 and Table 2.
All of the potentiometers must be set before the unit is
started in order for the unit to function properly. See Start-
Up, Potentiometers section on page 28 for information on
establishing set points. Each of the potentiometers has a valid
range that is used by the control. The valid range is defined
as the potentiometer’s resistance value that the control will
not consider to be in error. This is usually between 10% and
90% of the potentiometer’s total resistance. The control has
been programmed to accept an operational range for the po-
tentiometer, which may not be the same as the valid range.
Table 1 — Pin Terminal Connector J1
Thermistor Inputs
CONNECTOR J1
TERMINAL NO.
TEMPERATURE
INPUT
UNIT SIZE
034-104
1,2
Reset Temperature*
T10
Saturated Condensing
Temp., Circuit 2
14,15
16,17
T4
Saturated Condensing
Temp., Circuit 1
T3
18,19
20,21
Return-Air Temperature
Supply-Air Temperature
T2
T1
LEGEND
T — Thermistor
*If equipped with accessory temperature reset package.
NOTE: Terminal numbers 3-13 are not used on these units.
3
LEGEND
CR
—
—
—
Control Relay
Enthalpy Control
Low-Pressure Switch
EC
LEGEND
Thermistor
LPS
T
—
Field Wiring
Accessory
Fig. 3 — Pin Terminal Connector J2
Status Switch Inputs
Fig. 2 — Pin Terminal Connector J1
Thermistor Inputs
Table 2 — Pin Terminal Connector J2
Status Switch Inputs
CONNECTOR J2
TERMINAL NO.
UNIT SIZE
034-104
STATUS SWITCH
Oil Pressure,
Circuit 2
1,2
Jumpered
Oil Pressure,
Circuit 1
3,4
Jumpered
LPS2
LPS1
EC
Loss Of Charge,
Circuit 2
7,8
Loss of Charge,
Circuit 1
9,10
Economizer
Changeover
13,14
15,20
15,24
LEGEND
Compressor Fault
Signal
CR2
Compressor Fault
Signal
LEGEND
CR1
IN
—
—
—
—
Input
Factory Wiring
Field Wiring
Accessory
P
Potentiometer
Return
RNT
SW
CR
—
—
—
Control Relay
Switch
EC
Enthalpy Control
LPS
Low-Pressure Switch
Fig. 4 — Pin Terminal Connector J3
Potentiometer Inputs
NOTE: Terminal numbers 5, 6, 11, 12, 16-19, and 21-23 are not used
on these units.
4
The potentiometer locations and functions are as follows:
The configuration header (part no. 30GB660001) is a
series of 8 small wires that are broken or unbroken in a
pattern to indicate several unique characteristics of the unit.
The configuration header is factory set and should not be
changed. Changing the factory setting may cause the unit to
malfunction.
The DIP switches configure the unit for several field-
installed options, as well as for several other options that
may be unique to the unit. The DIP switches are located un-
der a plastic enclosure which must be removed for access.
The switches can be field adjusted, but must be adjusted only
when the unit control circuit breaker is off.
P1 — SUPPLY-AIR SET POINT — This potentiometer is
located on the display board. The supply-air set point is the
cooling mode control temperature which the VAV control
system will attempt to maintain at Thermistor T1 by con-
trol of economizer position and/or cycling unloaders and
compressors.
P2 — ECONOMIZER POSITION — Economizer feedback
potentiometer is located on the economizer motor. The micro-
processor is programmed to indicate an alarm if the travel
during initialization is less than 10% of the total potentiom-
eter’s resistance. An alarm condition will also be signaled if
the potentiometer fails during operation, indicating that the
damper blades are stuck. If either situation occurs, the pro-
cessor will try to drive the economizer dampers closed.
Relay Board — The relay board is used to control 24-v
and 115-v loads. See Fig. 5. The relay board is connected to
the processor board by a ribbon cable at pin J9. Electrical
connections to the relay board are made through pins J5
(115 v) and J6 (24 v). The relay board has eight 24-v relays
and five 115-v relays. See Table 3.
P3 — RESET LIMIT — This potentiometer is located on
the accessory board (provided standard from the factory) in
the unit main control box and establishes the maximum amount
of reset that can be applied to the supply-air set point (P1).
Reset is limited by the P1 default of 70 F. This potentiom-
eter is used only when accessory, field-installed temperature
reset is used. If temperature reset is used, DIP (dual, in-line
package) switch 2 must be in the ON position.
Display Board — The display board is located in the
main unit control box and is connected to the J10 port of the
processor board through a ribbon cable. The display board
contains the supply-air set point potentiometer P1; a 2-digit,
LED display; and the display button (see Fig. 6). The LED
display is used to convey the operating information and op-
erational error codes.
P4 — DEMAND LIMIT — This potentiometer is located
near TRAN4 in the unit control box. The demand limit po-
tentiometer is used only if accessory, field-installed demand
limit is used, and if DIP switch 5 is in the ON position. For
single-step demand limit, a field-installed 5 to 20 Kohm po-
tentiometer and switch must be used.
Thermistors — The processor uses up to 5 thermistors
to sense the temperatures at various points in the system.
See Table 1 and Fig. 7-14. All the thermistors have identical
temperature versus resistance and voltage drop characteris-
tics, and are monitored by the processor for a short or open
circuit. The valid range for a thermistor is 362,640 to
219 ohms. Thermistor details and locations are as follows:
T1 — SUPPLY-AIR TEMPERATURE THERMISTOR —
This thermistor is located in the unit supply fan discharge.
It provides information for the processor to stage the num-
ber of capacity steps required to maintain a desired supply-
air temperature.
P5 — ECONOMIZER MINIMUM POSITION — This po-
tentiometer is on the accessory board (provided standard from
the factory) located in the unit main control box. This po-
tentiometer specifies the minimum opening position for the
optional economizer. If a fault condition is detected by the
processor, an alarm condition will be signaled and the econo-
mizer dampers will close.
P6 — WARM-UP SET POINT — This potentiometer is on
the accessory board (provided standard from the factory)
located in the unit main control box. This potentiometer
establishes the set point temperature for the Morning
Warm-Up function. When the temperature is reached, Morn-
ing Warm-Up is terminated and VAV operation begins. DIP
switch 4 must be in the ON position if morning warm-up
heat is to be used.
T2 — RETURN-AIR TEMPERATURE THERMISTOR —
This thermistor is located in the mixed-air portion of the unit
cabinet. The thermistor’s primary function is to provide morn-
ing warm-up information. This sensor will also provide dif-
ferential information for the processor during cooling opera-
tion (such as the rate of change for a capacity step).
P7 — SASP (SUPPLY AIR SET POINT) RESET TEM-
PERATURE — This 10 Kohm potentiometer is used only if
the accessory, field-installed temperature reset package is in-
stalled. This potentiometer determines the temperature at which
reset will begin. It is located on the accessory temperature
reset board. DIP switch 2 must be in the ON position to en-
able SASP reset.
T3 — SATURATED CONDENSING TEMPERATURE, CIR-
CUIT 1 — This thermistor is located on the condenser coil
return bend. See Fig. 13 and 14. It controls the staging of the
unit condenser fans based on the condensing temperature of
the refrigerant at the designated position on the condenser
coil.
T4 — SATURATED CONDENSING TEMPERATURE, CIR-
CUIT 2 — This thermistor is located on the condenser coil
return bend. See Fig. 13 and 14. It controls the staging of the
unit condenser fans based on the condensing temperature of
the refrigerant at the designated position on the condenser
coil.
PROCESSOR BOARD OUTPUTS — The processor board
also controls outputs through the relay board. The relay board
plugs into the processor board using a ribbon cable.
In addition, the processor board controls the display board.
The display board is connected to the processor board by a
ribbon cable, and has an LED (light-emitting diode) display
showing the status of the unit and diagnostic information.
T10 — RESET TEMPERATURE — This thermistor is used
only if the accessory temperature reset package is used. It
provides occupied space temperature information to the pro-
cessor, which determines whether or not reset is required.
The thermistor is remotely mounted outside the unit in the
conditioned space.
CONFIGURATION HEADER AND DIP SWITCHASSEM-
BLY — The processor board is programmed to control a va-
riety of air conditioning units. To tailor the processor to the
particular unit being controlled, 2 devices are used. One is
the configuration header, and the other is the DIP switch
assembly.
5
Table 3 — Output Pin and Terminal Assignments
OUTPUT PIN-
TERMINAL
NAME
RATING
DEVICE
CR1
Stage 1
J6-1
J6-2
J6-3
J6-4
J6-5
J6-6
Compressor Relay (K1)*
Stage 2
U2**
Compressor Relay (K2)*
Stage 3
U1
Compressor Relay (K3)*
Stage 4
Not Used
CR2
24 vac
Compressor Relay (K4)†
Stage 5
Compressor Relay (K5)†
Stage 6
Not Used
Compressor Relay (K6)†
J6-7
J6-8
J5-1
J5-2
Economizer Open Relay (K7)
Economizer Close Relay (K8)
Supply Fan Relay (K9)
EOR
ECR
IFC
Morning Warm-Up Relay (K10)
HIR
Stage 1 Condenser
Fan Relay (K11)
J5-3
OFC2/OFC3 ††
115 vac
Stage 2 Condenser
Fan Relay (K12)
J5-4
OFC4
J5-5
External Alarm Relay (K13)
ALM
LEGEND
*Circuit 1.
†Circuit 2.
ALM
CR
—
—
—
—
—
—
—
—
Alarm
Control Relay
Economizer Close Relay
Economizer Open Relay
Heat Interlock Relay
**U2 is not used on 044 units.
††OFC2 on 034-048 units; OFC3 on 054-104 units.
Used on 054-104 units only.
ECR
EOR
HIR
IFC
OFC
U
Indoor (Evaporator) Fan Contactor
Outdoor (Condenser) Fan Contactor
Unloader
LEGEND
CR
J
K
—
—
—
Control Relay
Terminal Pin Connectors
Relay
Fig. 5 — Relay Board
6
P3 — RESET LIMIT — The processor board is programmed
for occupied space temperature reset. In order for reset to
work, the accessory temperature reset board must be used.
Potentiometer P3 is the maximum set point temperature to
which the supply air can be reset.
P1 SUPPLY AIR
SET POINT
POTENTIOMETER
TWO-DIGIT
DISPLAY
DISPLAY
BUTTON
P5 — ECONOMIZER MINIMUM POSITION — This po-
tentiometer controls the set point for the minimum position
of the economizer.
P6 — MORNING WARM-UP TEMPERATURE — This po-
tentiometer controls the morning warm-up temperature set
point.
Single-Step Demand Limit — The single step de-
mand limit provides a means to limit the capacity of the VAV
unit using an external switch. Single step demand limit will
limit the compressor displacement based on the ratio of the
wiper arm to the full scale resistance. The exact percentage
of capacity reduction differs depending on the number of ca-
pacity steps.
A 3-wire, 5 to 20 Kohm, field-supplied potentiometer (P4)
is required for this option. The potentiometer should be wired
to the processor J3 connections. In order to control the de-
mand limit, the wiper arm of the potentiometer should be
switched open and closed based on the demand limit
requirement. The control switch is also field-supplied and
installed.
If the wiper arm wire is open, all capacity stages can be
used. When the wiper arm wire is closed, the capacity is
reduced by the amount set on potentiometer P4.
Fig. 6 — Display/Set Point Board
Compressor Operation
CONTROL RELAY (CR) — This relay provides informa-
tion to the processor about compressor operation (one con-
trol relay per compressor). The relay controls and protects
the compressor and also controls the crankcase heater.
Demand Limit Control Module (DLCM) — The
DLCM provides a 2-step demand limit control using an ex-
ternal switch. The first step is between 50% and 100% of the
maximum compressor displacement. See Fig. 16. The sec-
ond step is between 0% and 49% of the maximum compres-
sor displacement. The exact percentage differs depending on
the number of capacity steps.
Two adjustable potentiometers are used to set the 2 de-
mand limit points. Potentiometer P1 is used to set a demand
limit between 50% and 100% of the unit capacity. Potenti-
ometer P2 is used to set a demand limit between 0% and
49% of unit capacity.
If no power is supplied to the demand limit control mod-
ule, all capacity stages can be used. When power is supplied
to terminal IN1 only, the first step of the demand limit con-
trol is energized and the capacity is reduced by the amount
set on potentiometer P1. When power is supplied to terminal
IN2 only, or to both IN1 and IN2, the capacity is reduced by
the amount set on potentiometer P2.
A control signal to check the safety statuses and to start
the compressor is sent from the relay board. This signal trav-
els through all of the safeties: the high-pressure switch, and
the internal protector (where used) and on to the control re-
lay coil. Once the control relay coil has been energized, the
control relay completes a feedback circuit for the processor,
informs the processor of the status of the compressor safe-
ties, energizes the compressor contactor coil, and deener-
gizes the crankcase heaters. A fault will be detected by the
processor if the control relay opens during operation or start-
up. The processor will lock the compressor or the circuit off
by deenergizing the appropriate relay(s) on the relay board
and energizing an alarm signal.
Accessory Board — The accessory board is standard
(factory supplied) in the VAV rooftop units. See Fig. 15. This
board is located in the control box of each unit. Each board
has a prewired connector supplied with it to connect directly
to the processor board. It has 3 potentiometers: P3, P5, and
P6.
7
GAS SECTION
(48FK,JK ONLY)
HORIZONTAL SUPPLY SECTION
(50FY,JY ONLY) AND EXTENDED
PLENUM SECTION (50FKX,FKY,JKX,JKY)
Fig. 7 — Thermistor T1 Location, 48FK,JK, 50FY,JY and 50FKX,FKY,JKX,JKY 034-048 Units
FAN DISCHARGE/ELECTRIC HEAT SECTION
Fig. 8 — Thermistor T1 Location, 50FK,JK034-048 Units
8
GAS SECTION
(48FK,JK)
HORIZONTAL DISCHARGE SECTION (50FY,JY)
AND EXTENDED
PLENUM SECTION (50FKX,FKY,JKX,JKY)
Fig. 9 — Thermistor T1 Location, 48FK,JK, 50JY and
50JKX,JKY 054-074 Units and 50FKX,FKY and 50FY054-104 Units
FAN DISCHARGE/ELECTRIC HEAT SECTION
Fig. 10 — Thermistor T1 Location, 50FK,JK054-074 Units
9
STANDARD
FILTERS
BAG
FILTERS
Fig. 11 — Thermistor T2 Location, Size 034-048 Units
Fig. 13 — Thermistor T3 and T4 Locations,
Size 034-048 Units
ENTHALPY CONTROL — Outside air enthalpy control is
standard with the factory-installed economizer option. En-
thalpy is sensed by a controller located behind the end out-
side air hood. The control can be accessed by removing the
upper hood filter. See Fig. 17.
DIFFERENTIAL ENTHALPY —Added efficiencies in econo-
mizer control can be gained by installing a differential en-
thalpy sensor in the return air duct. When differential enthalpy
control is installed, the economizer control will use the air
stream with lower enthalpy (outside air or return air) to pro-
vide for lower compressor operating costs during integrated
economizer cycle operation. The differential enthalpy sen-
sor is installed in the return-air duct.
STANDARD FILTERS
BAG FILTERS
(054-074 Only)
Fig. 12 — Thermistor T2 Location, Size 054-104 Units
Economizer — Economizer control is used to control
the outside and return air dampers of the unit, to satisfy space
cooling demand using all outside air (when permitted), and
to satisfy cooling in conjunction with compressor operation
(when conditions permit). During Occupied periods without
cooling demand, the outside-air dampers will be at the user-
configured Minimum Damper Position (at P5 on accessory
board). During Unoccupied periods, the outside-air dampers
will be closed.
The economizer is available as a factory-installed option.
The user can install an accessory differential enthalpy sensor
to enhance economizer control. Refer to the installation sec-
tion for field wiring of the sensor.
10
054 UNITS
064, 074, 078 UNITS
088, 104 UNITS
Fig. 14 — Thermistor T3 and T4 Locations, Size 054-104 Units
11
Variable Frequency Drive (VFD) — The optional
VFD is used to modulate supply fan airflow to maintain duct
static pressure on VAV applications. The VFD is located in
the supply fan section (see Fig. 18 and 19), and can be ac-
cessed by opening the fan section access door.
The unit is supplied with a pressure transducer capable of
measuring from 0.0 to 5.0 in. wg. The pressure transducer
will send a 4 to 20 mA signal to the VFD to modulate the
speed of the indoor fan motor to precisely control the fan to
the desired static pressure set point. The VFD is factory set
at 2.5 in. wg duct static pressure. Refer to the Operating Se-
quence section for more information on the VFD.
The VFD has been programmed and wired at the factory
for this application. No further adjustments (except for Duct
Static Pressure Set Point) should be necessary at start-up.
Factory jumper wire configurations are shown in the Supply
Fan Control with VFD Option section on page 28.
A separate service manual for the factory-installed VFD
is supplied with each unit. Refer to the VFD manual for more
information on the VFD controls.
Temperature Reset — Accessory temperature reset al-
lows the unit to automatically adjust (‘‘reset’’) the supply-
air temperature set point to a higher value once most of the
space cooling load has been met. When the space conditions
are satisfied, the VAV terminals will close to the minimum
position. All VAV units will sense the decrease in actual supply-
air temperature and the unit controls respond by reducing
LEGEND
ECON
MIN
P
—
—
—
—
Economizer
Minimum
Potentiometer
Variable-Air Volume
VAV
Fig. 15 — Accessory Relay Board
(Standard; Factory Supplied)
LEGEND
IC
—
Integrated Circuit
Input
Potentiometer
Return
IN
—
—
—
P
RTN
Fig. 16 — Two-Step Demand Limit Module
Fig. 18 — Variable Frequency Drive,
Sizes 034-048 and 078-104
Fig. 17 — Enthalpy Sensor Location
Fig. 19 — Variable Frequency Drive, Sizes 054-074
12
capacity stages to maintain user-established supply-air set
point temperature. When VAV units are also equipped with
optional supply duct pressure controls (either inlet guide vanes
[IGV] or variable frequency drive package), the unit also senses
an increase in duct static pressure and responds by closing
IGV dampers or slowing fan wheel speed to maintain user-
configured set points for supply duct pressure. Allowing the
supply-air temperature to be reset to a higher value main-
tains air circulation in the space without costly overcooling.
There are no required 115-volt field wiring connections,
therefore no provisions have been made in the unit for run-
ning 115-volt wiring. If any of the field-installed options re-
quiring 115-volt connections are desired, the unit must be
modified in the field for 115-volt wiring.
NIGHT SETBACK THERMOSTAT — Wire field-supplied
thermostat (suitable for 24-v circuit) between terminals 1 and
2 on terminal block 3 (sizes 034-048) or terminal block 4
(sizes 054-104). This thermostat is used to bypass the time-
clock occupied/unoccupied switch and is used to operate unit
during unoccupied times at more economical temperatures.
(See Fig. 23.)
The accessory package is required for temperature reset.
The accessory includes:
• thermistor T10, to monitor space temperature
SPACE TEMPERATURE RESET ACCESSORY
(50DJ900021) — Consists of a thermistor (T10) and a reset
board with a potentiometer (P7) that is used to set space tem-
perature at which reset starts. Mount reset board in unit
control box or other convenient place. Wire thermistor in se-
ries with P7 and connect to terminals 12 and 15 on terminal
block 3 (sizes 034-048) or terminal block 4 (sizes 054-104)
in unit control box. If there is a long run to conditioned space,
it is necessary to splice additional wire to thermistor. The
reset board has 2 pressure connectors for field wiring. (See
Fig. 25).
• reset temperature potentiometer P7, to establish start tem-
perature for reset operation
• reset limit potentiometer P3, to establish maximum level
of modified supply-air temperature
More than one space sensor may be used if an average
space temperature is desired for initiating temperature reset.
Refer to installation section for sensor part number and wir-
ing schematic.
Temperature reset will start when space temperature (at
T10) drops to the set point at P7. When Temperature Reset
is active, the LED (light-emitting diode) display will show
code
. Automatic adjustment of supply-air temperature
21
Space Temperature Reset
set point will end when modified SASP equals reset limit set
point at P3. (See formula for automatic modification of SASP
in Controls Installation, Space Temperature Reset section on
this page.)
INSTALLATION — Install the accessory temperature reset
package in accordance with instructions provided with the
accessory kit.
Mount the reset board in the unit control box (or other
suitable location) per instructions.
CONTROLS INSTALLATION
Locate the thermistor T10 in a suitable location in the oc-
cupied space per instructions.
Wire T10 to the reset board and to the unit control ter-
minal block per Fig. 25. Wire the other terminal on the reset
board to the unit control terminal block per Fig. 25.
If multiple sensors are required to average the space tem-
perature, see Fig. 26. Use only Carrier Part Number
HH79NZ014 sensor, in arrangements of 4 or 9 sensors, with
total wiring not to exceed 1000 ft.
To enable reset function, change DIP (dual in-line pack-
age) switch 2 to position ON. (Disconnect control power be-
fore changing DIP switch positions; reconnect power after
all changes have been made.)
The VAV units may be used in applications with addi-
tional control features, options, or accessories. Refer to the
appropriate accessory installation instructions for more in-
formation on installing that accessory. Unit control box com-
ponent arrangement is shown in Fig. 20-22. Control options
and accessories available for VAV units are:
• smoke control modes
• differential enthalpy sensor
• electric heaters (sizes 034-074 only)
• modulating power exhaust
• Motormaster I control
• space temperature reset
• night setback thermostat (field-supplied)
• single step demand limit
CONFIGURATION — Set points for reset operation are es-
tablished at potentiometers P7 and P3 (on the reset board).
• two-step demand limit
Potentiometer P7 — Reset temperature set point (tempera-
ture at which reset function will start). Maximum of 80 F,
minimum 0° F. Set below normal room cooling set point level
to sense overcooling in the occupied space.
NOTE: It is difficult to accurately set the P7 potentiometer
to the desired set point. Use the procedure below.
Proper setting of the P7 potentiometer may be made on a
resistance basis. The microprocessor initiates reset when it
detects a resistance of the thermistor plus the potentiometer
of 13,084 ohm. The potentiometer set point may be calcu-
lated using the following formula:
• inlet guide vanes
• variable frequency drive
• variable frequency drive remote display kit
Control Wiring — A switch or timeclock (field sup-
plied) must be wired in to control when unit will go into and
out of Occupied mode. Connect switch or timeclock be-
tween terminals 1 and 2 on terminal block 3 (sizes 034-048)
or terminal block 4 (sizes 054-104) in unit control box. See
Fig. 23. The circuit potential is 24 v.
Variable air volume units equipped with warm-up heat re-
quire that room terminals be controlled to go fully open when
unit goes into the Heating mode. Heating interlock relay (HIR)
is provided for this function. The relay is located in the unit
control box. When unit goes into Heating mode, interlock
relay is energized providing switch closure or opening (de-
pending on how field power source is set up) to open the
room terminals. Field connections for interlock relays are
terminals 3 and 4 (for normally open contacts) and terminals
3 and 7 (for normally closed contacts) on terminal block 3
(sizes 034-048) or terminals block 4 (sizes 054-104). See
Fig. 24. Note that a field-supplied power source is required.
P7R = 13,084 – T10R
Where:
P7R = the desired set point of the P7 potentiometer in ohms
T10R = the resistance of the T10 thermistor for the desired
set point
13
14
15
16
034-048: TB3
054-104: TB4
034-048: TB3
054-104: TB4
Control will automatically adjust leaving air temperature by
the following formula:
MSP = SP + [(P3 - SP) / 3] x (P7 − T10)
where:
1
2
MSP = Modified Leaving-Air Set Point
SP = Supply-Air Set Point
OCCUPIED/UNOCCUPIED
SWITCH
P3 = Maximum Supply-Air Temperature (reset limit)
P7 = Reset Initiation Temperature (reset set point)
T10 = Actual Space Temperature
NIGHT SETBACK THERMOSTAT
3
= Ratio for reset (F) (fixed parameter)
Table 4 — Thermistor Resistance and
Voltage Drop Characteristics
NOTES:
1. Occ/Unocc switch closes when occupied.
TEMP
(F)
RESISTANCE
(Ohms)
VOLTAGE
DROP (v)
2. Night setback thermostat closes when in night setback heating.
31.0
32.0
33.0
34.0
35.0
36.0
37.0
38.0
39.0
40.0
41.0
42.0
43.0
44.0
45.0
46.0
47.0
48.0
49.0
50.0
51.0
52.0
53.0
54.0
55.0
56.0
57.0
58.0
59.0
60.0
61.0
62.0
63.0
64.0
65.0
66.0
67.0
68.0
69.0
70.0
71.0
72.0
73.0
74.0
75.0
76.0
77.0
78.0
79.0
80.0
16813.8
16345.7
15892.2
15452.7
15026.7
14613.9
14213.6
13825.5
13449.2
13084.2
12730.1
12386.6
12053.3
11730.0
11416.1
11111.5
10815.8
10528.7
10250.0
9979.3
9716.5
9461.3
9213.4
8972.6
8738.6
8511.4
8290.6
8076.1
7867.7
7665.1
7468.3
7277.1
7091.2
6910.6
6735.1
6564.4
6398.6
6237.5
6080.8
5928.6
5780.6
5636.8
5497.0
5361.2
5229.1
5100.8
4976.0
4854.8
4736.9
4622.4
3.582
3.553
3.523
3.494
3.464
3.434
3.404
3.373
3.343
3.312
3.281
3.250
3.219
3.187
3.156
3.124
3.093
3.061
3.029
2.997
2.965
2.933
2.901
2.869
2.837
2.805
2.772
2.740
2.708
2.676
2.644
2.612
2.581
2.549
2.517
2.486
2.454
2.423
2.391
2.360
2.329
2.299
2.268
2.237
2.207
2.177
2.147
2.117
2.088
2.058
Fig. 23 — Occupied/Unoccupied Switch with
Night Setback Thermostat
034-048: TB3
054-104: TB4
FIELD
SUPPLIED
POWER
SOURCE
3
V
4
6
5
N.O.
N.C.
4
7
SIGNAL
TO ROOM
TERMINALS
Fig. 24 — Heat Interlock Relay
034-048: TB3
054-104: TB4
T10
12
RESET
BOARD
P7
15
Fig. 25 — Accessory Reset Board
EXAMPLE:
T10 desired set point is 70 F.
T10R from Table 4 for 70 F is 5929 ohms.
P7R = 13,084 – 5929
P7R = 7155 ohms
Using an ohmmeter, set the P7 potentiometer to
7155 ohms to achieve a reset initiation set point of 70 F.
Potentiometer P3 — Reset limit set point (maximum tem-
perature value for modified supply air set point). Maximum
of 70 F, minimum 40 F. Set between leaving air set point
(P1) and 70 F (maximum range permitted by control).
OPERATING SEQUENCE — If space temperature is above
reset set point (T10 > P7), no reset will occur.
If space temperature is equal to or less that reset set point
20
(T10 р P7), the LED will display
and reset will begin.
17
RED
BLK
RED
BLK
SIZES 034-048
TB3
RED
RED
BLK
RED
BLK
12
15
BLK
TO ACCESSORY SPACE
TEMPERATURE RESET
CONTROL BOARD
SIZES 054-104
TB4
12
15
SENSOR 1
SENSOR 2
SENSOR 3
SENSOR 4
SPACE TEMPERATURE RESET — 4 SENSOR AVERAGING APPLICATION
SIZES 034-048
TB3
12
RED
RED
BLK
RED
BLK
BLK
15
TO ACCESSORY SPACE
TEMPERATURE RESET
CONTROL BOARD
SENSOR 1
SENSOR 3
SENSOR 2
SIZES 054-104
TB4
12
RED
BLK
RED
BLK
15
SENSOR 4
SENSOR 5
SENSOR 6
NOTE: Sensor part number is HH79NZ014.
RED
BLK
RED
BLK
SENSOR 7
SENSOR 8
SENSOR 9
SPACE TEMPERATURE RESET — 9 SENSOR AVERAGING APPLICATION
Fig. 26 — Space Temperature Sensor Averaging
Control Module kit plus installation of 2 field-supplied con-
trol switches (SPST-NO each). This accessory control pro-
vides for a first step reduction of 50% to 100% of the maxi-
mum compressor staging; the second step provides for reduction
between 0% and 49%. The exact percentage of capacity re-
duction differs depending on the number of capacity steps.
Demand Limit — The demand limit function provides
a means to limit the cooling capacity of the VAV unit using
an external discrete switch function. When enabled by the
closure of the external switch, the control will limit the avail-
able compressor staging capacity according to user set points
established at demand limit potentiometer(s).
When demand limit is active, the LED display will show
The unit controls support two types of demand limit: single-
step and 2-step control.
22
code
.
SINGLE-STEP DEMAND LIMIT — This function will limit
the total compressor staging based on the ratio of the set point
potentiometer’s wiper arm position to the full scale resis-
tance of the potentiometer. The exact percentage of capacity
reduction differs depending on the number of capacity steps.
A field-supplied potentiometer and control switch are re-
quired for this function. See installation section for speci-
fication on potentiometer and field wiring.
INSTALLATION
Single-Step Demand Limit — A 3-wire 5 to 20 K-ohm po-
tentiometer must be field-supplied and installed. A single-
pole normally open switch is also required (field-supplied
and -installed). Locate the potentiometer (designated P4) and
the switch in a suitable location (external from the unit or in
the unit control box).
TWO-STEP DEMAND LIMIT — Two-step demand limit is
provided with the installation of the accessory Demand Limit
18
Connect the potentiometer end terminals to terminals 8
and 9 on control terminal block TB3 (sizes 034-048) or TB4
(sizes 054-104) (see Fig 27). Connect the switch terminals
to the potentiometer wiper arm terminal and to terminal 10
on TB3 or TB4.
034-048: TB3
054-104: TB4
8
To enable demand limit function, change DIP switch 5 to
position ON. (Disconnect control power before changing DIP
switch positions. Reconnect power after all changes have been
made.)
5-20K
POTENTIOMETER
(P4)
9
Set the potentiometer P4 to desired capacity reduction value.
Two-Step Demand Limit — Install the demand limit con-
trol module (DLCM) according to the installation instruc-
tions provided with the accessory. Disconnect existing leads
at connector J3 on the processor board (see instructions) and
connect the plug from the DLCM harness to connector J3.
10
SWITCH
Fig. 27 — Single-Step Demand Limit
Connect the field input control power wires (from the ex-
ternal control relays) at the terminal strips marked IN1, RTN1,
IN2 and RTN2 (see Fig. 28 and 29).
To enable demand limit function, change DIP switch 5 to
position ON. (Disconnect control power before hanging DIP
switch positions. Reconnect power after all changes have been
made.)
Set the potentiometers DLCM-P1 and DLCM-P2 to de-
sired capacity reduction values.
Check the operation of demand limit function by using
the Quick Test procedures.
CONFIGURATION
Single-Step Demand Limit — Field-installed potentiom-
eter P4 establishes capacity reduction value for demand limit
operation. Set this potentiometer between 0% and 100%. The
exact percentage of capacity reduction differs depending on
the number of capacity steps.
Fig. 28 — Two-Step Demand Limit Module
Two-Step Demand Limit — Potentiometer P1 and P2 (lo-
cated on the accessory demand limit control module) estab-
lish the capacity reduction values for each step of demand
limit. Set potentiometer DLCM-P1 between 50% and 100%.
Set potentiometer DLCM-P2 between 0% and 49%. The ex-
act percentage of capacity reduction differs depending on the
number of capacity steps.
NOTES:
OPERATING SEQUENCE
1. Demand limit switches are field supplied and wired.
2. Demand limit control module terminal blocks will accept up to
12-gage wire.
Single-Step Demand Limit — If the field control switch to
the wiper arm terminal is open, all capacity stages will be
available (no demand limit in effect). When the field control
switch is closed, the compressor cooling capacity is reduced
by the amount set on potentiometer P4.
is field wiring.
3.
Fig. 29 — 115-Volt Field Wiring to Accessory
2-Step Demand Limit Control Module
When demand limit is in effect, the LED display will show
code 22 . If a potentiometer setting or input is out of range,
the control will terminate the demand limit function and show
Control From Remote Building Management Sys-
tem (BMS) — The unit control system is not a commu-
nicating control system, and it cannot be accessed directly
by a DDC (Direct Digital Control) control system (or by a
BACnet communication system). However, it is possible to
control some functions of these units via 4 to 20 mA or 2 to
10 vdc signals and discrete inputs (relay contact closures).
Functions that can be managed from or accessed from an
external control system include:
• Occupied/Unoccupied Status
• Night Setback Control
• Unit Supply Air Set Point Adjustment
• Demand Limit (1-stage or 2-stage)
• Supply Duct Pressure Set Point Adjustment
• External Alarm Signal
Remote control of the economizer cycle on these units is
not recommended. Refer to the Operating Sequence section
on page 35 for a discussion on the economizer cycle
operation.
code
at the display LED.
84
Two-Step Demand Limit — If the field control switches are
both open (no power supplied to the Demand Limit Control
Module), all capacity stages will be available (no demand
limit in effect). When control power is supplied to terminal
IN1 only (field switch SW1 closes), the first step of the de-
mand limit is energized and the compressor cooling capacity
is reduced by the amount set on potentiometer DLCM-P1.
When control power is supplied to terminal IN2 (field switch
SW2 closes), the second step of the demand limit is ener-
gized and compressor cooling capacity is reduced by the amount
set on potentiometer DLCM-P2.
When demand limit is in effect, the LED display will show
code 22 . If a potentiometer setting or input is out of range,
the control will terminate the demand limit function and show
code
at the display LED.
84
19
OCCUPIED/UNOCCUPIED — The unit control system will
initiate normal occupied mode functions (including Morn-
ing Warm-up, Economizer Minimum Position, and Cooling
Cycle) whenever a contact closure is made that emulates the
normal timeclock contacts. See Fig. 23. (‘‘Occupied/Unoccupied
Switch’’). The contact closure from the BMS must be an iso-
lated contact set, normally open, and suitable for 24-volts
AC pilot duty.
Configuration — Configure as follows:
1. Set DIP switch no. 2 to ON.
2. Adjust manual potentiometer to 12.6 to 12.8 k-ohm.
3. Configure transducer for job site input signal from BMS.
4. Adjust Potentiometer (P3) on the rooftop to MAXIMUM
SASP value (typically 65 to 70 F). The maximum P3 SASP
control limit is 70 F.
NIGHT SETBACK CONTROL — Night setback control is
used to control the space to a set point level that is typically
lower than during normal occupied periods (Heating Only
mode). Some applications also require a limitation on the
maximum space temperature during unoccupied periods (Cool-
ing mode). Both modes are possible by closing the same con-
tacts used in the Occupied/Unoccupied control, or by installing
a dedicated contact set in parallel with the Occupied/
Unoccupied control contacts, and using the BMS space tem-
perature sensing system and its logic to determine when to
initiate unit operation.
Operation —Unit will initiate SASP Reset (adjust config-
ured SASP upward) when the sum of the resistance (fixed
resistance + potentiometer + transducer) exceeds 13.1 k-ohm.
Once reset is initiated, full range of reset (P3 setting minus
configured SASP) will be reached with 500-ohm increase in
transducer resistance (TR).
During Reset mode operation, Code 21 will appear on unit
display board.
Formula:
MSP = SASP +
Once the unit operation has been initiated by the BMS
contact closure, the unit operates in its normal occupied mode
manner, initiating morning warm-up if needed (as sensed by
return air temperature to the unit) or cooling (controlling to
current SASP value). The Night Setback Control contacts
will interrupt normal unit operation when the BMS senses
that space temperatures have returned to unoccupied set point
levels, and the unit will shutdown normally.
(P3 − SASP)
(3)
(0.6 F)
x
[
]
(100 ohm)
MSP: Modified SASP (SASP plus Reset)
TR: Resistance at transducer
[email protected]: TR required to reach 13.1 k-ohm start level
DEMAND LIMIT (1-STAGE OR 2-STAGE) — Both of the
Demand Limit functions on the units rely on external switches
to initiate the reset functions. Contact closures by the BMS
can be used in place of these switches. Contacts must be
isolated and suitable for 115-vac pilot duty operation.
For Single-Step Demand Limit, emulate function of switch
SW with contact closure controlled by the BMS. Set poten-
tiometer P4 manually at the unit control box. Alternatively,
potentiometer P4 might also be emulated by a variable re-
sistance transducer, with the BMS now able to adjust the
amount of demand limit.
For 2-Step Demand Limit, install the accessory Demand
Limit Control Module (DLCM) according the instructions
on page 18. Replace switch functions Switch 1 and Switch
2 with contact closures controlled by the BMS (see Fig. 29).
Follow unit control configuration instructions in the De-
mand Limit section on page 18.
The contact closure from the BMS must be an isolated
contact set, normally open, suitable for 24-volts AC pilot duty.
NOTE: If the rooftop unit is equipped with a VFD and night
setback cooling operation is intended, the fan system must
be controlled to permit FULL SUPPLY FAN AIR DELIV-
ERY during unoccupied cooling operation. This is most con-
veniently attained by replicating the HIR relay function of
the rooftop unit. An HIR control sequence will force all room
terminals to their minimum heating CFM position, thus as-
suring adequate airflow through the rooftop unit during night
setback cooling operation. During night setback cooling op-
eration, the return-air temperature (RAT) will be well above
normal levels. The higher RAT means that the air tempera-
ture leaving the evaporator coil will also be well above nor-
mal levels. This situation is interpreted by the unit control
system as a demand for additional cooling stages. The unit
control responds to this demand by bringing on more stages,
until typically all stages are active. If the VFD is not work-
ing in-step with the refrigeration system demand, it is pos-
sible to produce low suction pressures and local frosting
on the evaporator coil during the night setback cooling
operation.
SUPPLY DUCT PRESSURE SET POINT ADJUSTMENT
— Supply duct pressure set point adjustment from a remote
BMS is possible when the unit has been equipped with a
factory-option VFD (variable frequency drive). There are two
methods available:
• Direct 4 to 20 mA signal
• DDC direct to the VFD
UNIT SUPPLY AIR SET POINT ADJUSTMENT — The
minimum Supply Air Set Point (SASP) temperature is es-
tablished by the setting at Potentiometer P1 on the unit dis-
play board (see Fig. 6). The control point can also be adjusted
upward by emulating the function of the accessory Space
Temperature Reset package. The BMS can be used to cause
this reset by adjusting the resistance value in a variable re-
sistance transducer with a 4 to 20 mA or 2 to 10 vdc signal
generated by the BMS.
Direct 4 to 20 mA Signal — During normal unit operation,
the factory-installed VFD receives a 4 to 20 mA signal from
the Duct Pressure (DP) transducer which indicates current
supply duct pressure. The VFD then determines the appro-
priate fan speed (using its internal PID logic feature) and
adjusts its output to the supply fan motor to suit. It is pos-
sible to emulate this 4 to 20 mA control signal by the BMS,
which will transfer control of the VFD to the BMS.
This emulation requires the following field-supplied parts:
NOTE: When providing a direct 4 to 20 mA signal to the
VFD from a BMS with DP logic, disable the PID (propor-
tion integrated derivative calculation process) feature of the
VFD.
• Variable resistance transducer (Kele RES-1 or equivalent,
range 0 to 1000 ohms)
• Series resistance with potentiometer, suitable for manual
adjustment to 12.5 to 13.0 k-ohms total resistance
DDC Direct to the VFD — Several accessory interface boards
are available for the VFDs that permit direct communication
between the VFD and several BMS communication sys-
tems. Contact your Carrier representative for information on
selecting an appropriate accessory interface board and the
name of the local service office (for sale and installation of
the accessory boards).
Field Connections (see Fig. 30) — Connect fixed resistance
with manual potentiometer and variable resistance trans-
ducer in series.
Connect wiring to rooftop unit at:
Size 034-044: TB3-12 and TB3-15
Size 054-104: TB4-12 and TB4-15
20
034-048: TB3
054-104: TB4
EXTERNAL ALARM SIGNAL — The unit controls pro-
vide an external alarm status signal via a 115-vac output sig-
nal at the relay board J5, available at TB2-4 and TB2-5
(common). This signal can be forwarded to the BMS by add-
ing a signal relay at the alarm output, placing its coil across
terminals TB2-4 and TB2-5 and using its contacts to control
a discrete input to the BMS (see Fig. 31).
TRANSDUCER
BMS
P
CONTROL
R
12
(4 TO 20 MA
OR
2 TO 10 VDC
SIGNAL)
15
The alarm signal output is energized when any of the di-
agnostic codes is tripped.
REMOTE ECONOMIZER CONTROL — Economizer con-
trol is tightly integrated into the unit’s capacity control al-
gorithms and diagnostic routines. Consequently, control
modifications that interfere with this standard operating se-
quence are not recommended.
Economizer position is determined by the unit processor
board based on current outdoor air enthalpy status and cool-
ing capacity demand. The economizer damper actuator is a
floating point device with an internal brake and spring re-
turn. Its position is determined by the sequencing of relays
EOR (Economizer Open Relay) and ECR (Economizer Close
Relay). The economizer’s current position is sensed by the
processor board through position feedback potentiometer P2.
LEGEND
P
R
—
—
Manual Potentiometer
Fixed Resistor
Field Wiring
Fig. 30 — Remote SASP Wiring
TB2
TB2
4
5
LIGHT
Whenever the economizer position potentiometer signal
is not consistent with the processor board’s commanded po-
sition, a fault condition is determined by the processor board
and an alarm signal is initiated. The processor board also
attempts to return the economizer damper to its fully closed
position during this fault condition by energizing the ECR
relay.
R
RELAY
Any attempt to effect an external control of the econo-
mizer actuator will lead to an alarm condition and an auto-
matic response by the unit control to attempt to close the
dampers.
SIGNAL TO BMS
Smoke Control Modes — It is common practice to
use rooftop units for aid in building smoke control in the
event of a building fire. The available functions include: Fire
Shutdown, Pressurization, Evacuation, and Smoke Purge. These
functions are enhanced when multiple rooftop units are used
to zone a building.
LEGEND
R
—
Resistor (Factory Installed)
Factory Wiring
Field Wiring
Fig. 31 — External Alarm Indication
Implementation of the various Smoke Control modes on
these units requires the installer to modify the unit wiring to
add contacts (via either manual switches or relays) that will
selectively interrupt and override standard factory control se-
quences. See Table 5.
EVACUATION MODE — Evacuation mode removes smoke
or undesirable air from interior spaces without reintroducing
unsuitable air. Factory-installed, optional economizer with
optional or accessory power exhaust are required for this func-
tion. Evacuation is accomplished by:
FIRE SHUTDOWN MODE — Fire Shutdown mode termi-
nates all unit operation (cooling, heating, supply fan and power
exhaust). This mode prevents recirculation of contaminated
air back into the space or the admission into the space of
unsuitable outside air.
• turning supply fan off
PRESSURIZATION MODE — Pressurization mode is in-
tended to keep smoke out of a zone. Factory-installed op-
tional economizer is required for this function. Pressuriza-
tion is accomplished by:
• opening the economizer (option required for this function)
• running the exhaust fans (must be provided via option or
accessory)
• opening the exhaust dampers
• opening the economizer (option)
SMOKE PURGE MODE — Smoke Purge mode removes
smoke from the interior spaces and replaces it with fresh out-
side air. Factory-option economizer with optional or acces-
sory power exhaust are required for this function. Smoke purge
is accomplished by:
• turning supply fan on
• opening the economizer (option required for this function)
• running the exhaust fans (must be provided via option or
accessory)
• opening the exhaust dampers
• running the supply fan (optional inlet guide vanes open or
optional VFD (variable frequency drive) at normal duct
static pressure set point)
• closing the power exhaust dampers (if installed as option
or accessory)
• shutting off the power exhaust fans (if installed as option
or accessory)
This allows the space to be overpressurized relative to ad-
jacent zones and prevents or slows entry of smoke into this
space from adjacent zones.
21
INSTALLATION — To enable one or more of the possible
smoke control modes available with these units, determine
the switches required for the desired mode(s) from Table 6,
field-supply and install the appropriate switches and field wire
per Fig. 32. Switch functions are shown in Table 7.
Pressurization — At command from the field switches for
Pressurization mode (see Table 5):
1. Economizer dampers will open
2. The HIR function will energize, opening room terminals
to full-open (heating) positions.
3. Supply fan will run. (If equipped with IGV: control vanes
will open. If equipped with VFD: the VFD will control to
duct static set point or best available with all terminals
open.)
4. Power exhaust dampers (if equipped) will close.
5. Power exhaust fans (if equipped) will turn off.
Table 5 — Smoke Control Modes
MODE
FUNCTION
Fire
Shutdown
Pressur-
ization
Smoke
Purge*
Evacuation*
Supply Fan
IGV/VFD†
Off
—
On
Off
—
On
Open/On
Open
Open/On
Open
Evacuation — At command from the field switches for Evacu-
ation mode (see Table 5):
1. Supply fan will turn off.
2. Economizer dampers will open.
3. Exhaust fans will run at maximum capacity.
4. Exhaust dampers will open.
Economizer
Closed
Open
Return Air
Damper
Open
Off
Closed
Off
Closed
On
Closed
On
Exhaust
Fans
Exhaust
Damper
Closed
Closed
Open
Open
Smoke Purge — At command from the field switches for
Smoke Purge mode (see Table 5):
1. Economizer dampers will open.
2. The HIR function will energize, opening room terminals
to full-open (heating) positions.
3. Supply fan will run. (If equipped with IGV: Control vanes
will open. If equipped with VFD: the VFD will control to
duct static set point or best available with all terminals
open.)
LEGEND
IGV
VAV
VFD
—
—
—
Inlet Guide Vane
Variable Air Volume
Variable Frequency Drive
*Power exhaust option/accessory required for this mode.
†Applicable to VAV units with appropriate options.
CONFIGURATION — No set points required for Smoke Con-
trol modes. Modes are activated by energizing all switches
appropriate for each Smoke Control mode.
4. Exhaust fans will run at maximum capacity.
5. Exhaust dampers will open.
OPERATING SEQUENCE
Fire Shutdown — At command from the field switches (see
Table 5), all unit operation (cooling, heating, supply fan and
power exhaust) will terminate.
Table 6 — Smoke Control Switches Required for Each Mode
EVACUATION
(Modulating Power
Exhaust)
FIRE
SMOKE
PURGE
PRESSURIZATION
SHUTDOWN
SW-1
SW-2
SW-1
SW-2
SW-1
SW-2
SW-3
SW-5
SW-6
SW-7
SW-8
SW-1
SW-2
SW-4
SW-3
SW-5
SW-4
SW-6
SW-9A/B
SW-9A/B
NOTE: All switches are shown in ‘‘as installed’’ (power OFF or deenergized) position. In these positions, none of these
modes will be activated; normal unit operation is permitted by the base unit controls. To initiate any mode, all switches listed
under this mode in the table must be energized, causing the depicted contact position to change from depicted positions to
energized positions. Switches may be manually or electrically operated.
22
Table 7 — Switch Functions
SWITCH
NUMBER
CONFIGURATION
VOLTAGE
FUNCTION
SW-1
SW-2
SW-3
SW-4
SW-5
SW-6
SW-7
SW-8
N.C.
N.C.
N.O.
N.O.
N.C.
N.O.
N.O.
N.C.
115
115
24
Deenergize 115-v (OFC, Comp, IFC, Electric Heaters)
Deenergize TRAN7 (Process Board)
Energize EOR (Open Economizer Outside Air Dampers)
Energize IFC and CR-3 (IGV/VFD)
115
115
115
24
Isolate IFC and PEC for Separate Operation
Energize PEC (Power Exhaust)
Open PED at DPS
24
Block Auto-Close at DPS (Due to Low BP)
A: N.O.
B: N.C.
SW-9A/B
115 max
Signal Room Terminals to Open (HIR1)
LEGEND
Building Pressure
BP
—
—
—
—
—
—
—
—
—
—
—
—
DPS
EOR
HIR
Differential Pressure Switch
Economizer Open Relay
Heat Interlock Relay
Indoor Fan Contactor
Inlet Guide Vane
Normally Closed
Normally Open
Power Exhaust Contactor
Power Exhaust Damper
Outdoor Fan Contactor
Variable Frequency Drive
IFC
IGV
N.C.
N.O.
PEC
PED
OFC
VFD
The inlet guide vanes are controlled by a differential pres-
sure switch (DPS). On sizes 034-048, the DPS is located in
the auxiliary control box at the economizer end of the unit
(see Fig. 33). On sizes 054-104, the DPS is located in the
supply fan section. See Fig. 34. Use a nominal 3⁄8-in. plastic
tubing.
Air Pressure Tubing — Before options such as inlet
guide vanes (IGV), variable frequency drive (VFD), and/or
modulating power exhaust can operate properly, the pneu-
matic tubing for pressure sensing must be installed. Use fire-
retardent plenum tubing (field-supplied). Tubing size depends
on type of control device (see Table 8 below). Tubing must
be run from the appropriate sensing location (in the duct or
in the building space) to the control device location in the
unit.
VARIABLE FREQUENCY DRIVE — The tubing for the
duct pressure (DP) control option should sample supply duct
2
pressure about ⁄3 of the way out from the unit in the main
trunk duct, at a location where a constant duct pressure is
desired.
Table 8 — Tubing Size
NOMINAL TUBE
The duct pressure is sensed by a pressure transducer. The
pressure transducer output is directed to the VFD. On 034-
048 units the DP transducer is located in the auxiliary con-
trol box. On 054-104 units, the DP transducer is located in
OPTION
UNITS
ALL
SIZE (in.)
3
Inlet Guide Vanes (IGV)
⁄
⁄
⁄
8
4
8
Variable Frequency
Drive (VFD)
1
3
ALL
1
the supply fan section. See Fig. 34. Use a nominal ⁄4-in.
Modulating Power Exhaust FK,FKX,JK,JKX
plastic tubing.
INLET GUIDE VANES — The tubing for the duct pressure
(DP) control option should sample supply duct pressure about
2
⁄
3
of the way out from the unit in the main trunk duct, at a
location where a constant duct pressure is desired.
23
054-104 UNITS
034-048 UNITS
TB2
5
SW-1
TB2
6
TB2
13
SW-1
TB2
14
REMOVE JUMPER
REMOVE JUMPER
TB2
1
SW-2
TB2
2
TB2
7
SW-2
TB2
8
REMOVE JUMPER
REMOVE JUMPER
SW-3
SW-4
TB3
5
TB3
1
SW-3
SW-4
TB4
5
TB4
1
TB2
9
TB2
5
TB2
2
TB2
13
TB2
8
SW-5
TB2
9
TB2
1
SW-5
TB2
2
REMOVE JUMPER
REMOVE JUMPER
TB2
8
TB2
5
SW-6
TB2
1
TB2
13
SW-6
SW-9A
TB3
4
TB3
3
SW-9A
TB4
4
TB4
3
HIR
HIR
TB4
7
TB3
3
SW-9B
TB3
7
TB4
3
SW-9B
4
4
5
5
REMOVED FROM TB3-7
REMOVED FROM TB4-7
ALL UNITS
SW-7
SW-8
DPS
NC
WHT
C
VIO
NO
REMOVED
FROM C-DPS
GRA
LEGEND
DPS
HIR
SW
TB
—
—
—
—
Differential Pressure Switch
Heat Interlock Relay
Switch
Terminal Block
Fig. 32 — Smoke Control Wiring
24
MODULATING POWER EXHAUST — The tubing for the
building pressure control (achieved via the Modulating Power
Exhaust option) should sample building pressure in the area
near the entrance lobby (or other appropriate and sensitive
location) so that location is controlled as closely to design
pressures as possible.
A differential pressure switch (DPS) is used to control the
actuator on the modulating discharge damper in exhaust fan
no. 1. The building pressure (BP) DPS is located in the aux-
iliary control box of the unit. See Fig. 33 and 35. Use a nomi-
3
nal ⁄8-in. plastic tubing.
For instructions on adjusting BP control set points, refer
to Start-Up, Modulating Power Exhaust section in this book.
START-UP
Fig. 33 — Modulating Power Exhaust and Inlet
Guide Vane Differential Pressure Switch
(Sizes 034-048)
Initial Check
IMPORTANT: Do not attempt to start unit, even mo-
mentarily, until all items on the Controls Start-Up Check-
list (in installation instructions) and the following steps
have been completed.
1. Verify unit has been installed per the Installation Instruc-
tions included in the unit installation packet.
2. Verify that all auxiliary components (sensors, controls,
etc.) have been installed and wired to the unit control boxes
per these instructions, the unit Installation Instructions,
and the unit wiring label diagrams.
3. Verify that air pressure hoses (static, duct, etc.) are prop-
erly attached, routed, and free from pinches or crimps that
may affect proper control operation.
4. Set any control configurations that are required (field-
installed accessories, etc.). The unit is factory configured
for all appropriate factory-installed options with the ap-
plicable controls programmed to the default values.
5. Check and adjust unit set points. See Table 9.
6. Check tightness of all electrical connections.
Fig. 34 — Inlet Guide Vane Differential
Pressure Switch and Variable Frequency Drive
Duct Pressure Transducer (Sizes 054-104)
7. Perform quick test (see Quick Test Program section on
page 31).
Fig. 35 — Modulating Power Exhaust Differential
Pressure Switch (Sizes 054-104)
25
Table 9 — Potentiometer Inputs and Ranges
CONTROL
POTENTIOMETER
DESCRIPTION
LOCATION
VALID
DEFAULT VALUE
45 F if -22 F < P1 < 45 F
RANGE
Supply Air
Set Point
Display
Board
P1
45 to 70 F
0 to 100%
0 to 80 F
0 to 100%
70 F if P1 > 70 F OR IF P1 < -22 F
Economizer
Position
Economizer
Motor
P2*
P3
None (0 if P2 is bad)
Accessory
Board
Reset Limit
None (limited to 70 F maximum)
None
Demand Limit,
Single-Step
P4†
Main Control Box
DLCM-P1
DLCM-P2
DLCM Board
DLCM Board
50 to 100%
0 to 49%
None
None
Demand Limit,
2-Step
Minimum Economizer
Position
P5*
Accessory Board
Accessory Board
Reset Board
0 to 100%
40 to 80 F
40 to 100 F
None
40 F if 0° F < P6 < 40 F OR IF P6 < 95 F
OR IF P6 < 0
80 F if 80 F < P6 < 95 F
Warm-Up
Set Point
P6
Reset
Temperature
P7**
None
*Optional factory-installed economizer is required. Potentiometer P2 is not a set point.
†Accessory two-step demand limit module is required (which has 2 potentiometers), or a 5 to 20 k-ohm
field-supplied potentiometer is required for single-step demand limit.
**Accessory temperature reset is required.
NOTE: Potentiometers P1-P6 input data to pin terminal connector J3.
Potentiometer P7 inputs data to pin terminal connector J1.
Table 11 — Configuration Header Jumpers
Configuration Header — The configuration header
is a series of 8 small wires that are broken (open circuit) or
unbroken (closed circuit) in a pattern to indicate several unique
characteristics of the unit. The configuration header is fac-
tory set and should not be changed; changing the factory set-
ting may cause the unit to malfunction.
Before start-up, visually check the configuration header
against the factory setting for the unit size. See Table 10 for
factory settings. See Table 11 for purpose for each jumper.
JUMPER
FACTORY
SETTING
FUNCTION
Unit Type
MEANING
NUMBER
1,2
3,4,5
6
▫ Ⅲ
VAV Rooftop Unit
2 Compressors
TXV
Qty Compressors
Expansion Valve
Power Frequency
Not Used
Ⅲ ▫ ▫
Ⅲ
▫
Ⅲ
7
60 Hz
8
No Significance
LEGEND
TXV
VAV
▫
—
—
—
—
Thermostatic Expansion Valve
Variable-Air Volume
Table 10 — Configuration Header and
DIP Switch Factory Settings
Broken Jumper (open circuit)
Ⅲ
Unbroken Jumper (closed circuit)
UNIT SIZES
UNIT SIZE
044
UNIT SIZE
104
DIP Switches — The DIP switches configure the unit
for several factory-installed options and field-installed ac-
cessories, plus factory unloaders. The DIP switches are lo-
cated under a plastic enclosure which must be removed for
access. See Fig. 1. The switches can be field adjusted. Switches
must only be adjusted when control power is deenergized.
See Table 12 for DIP switch purposes and Table 10 for fac-
tory settings of the switch positions.
034-038,
048-088
JUMPER OR
SWITCH NO.
Header Switch Header Switch Header Switch
Position Position Position Position Position Position
1
2
3
4
5
6
7
8
▫
Ⅲ
Ⅲ
▫
▫
Ⅲ
▫
Ⅲ
Off
Off
▫
Ⅲ
Ⅲ
▫
▫
Ⅲ
▫
Ⅲ
Off
Off
▫
Ⅲ
Ⅲ
Ⅲ
▫
Ⅲ
▫
Ⅲ
Off
Off
On/Off*
On/Off*
Off
On/Off*
On/Off*
Off
On/Off*
On/Off*
Off
Off
On
On
On
Off
Off
Off
Off
Off
Disconnect control power before changing the settings
of the DIP switches. To disconnect control power, open
the control circuit breaker.
LEGEND
DIP
▫
Ⅲ
—
—
—
Dual, In-Line Package
Broken Jumper (open circuit)
Unbroken Jumper (closed circuit)
*Depending on factory-installed options or field-installed accessories.
26
DIP SWITCH NO. 1 — Supply Air Set Point (SASP) Reset
Type. Factory setting is OFF. Do not change.
Potentiometer inputs and ranges are summarized in
Table 9. Information on individual set point potentiometers
(including function, location and range data) are shown
below:
DIP SWITCH NO. 2 — SASP Reset Enabled. Factory set-
ting is OFF (no SASP reset enabled). If SASP reset has been
installed, enable it by changing switch position to ON.
SUPPLY AIR SET POINT (Leaving-Air Temperature) (P1)
— This potentiometer establishes the set point for cooling
cycle operation of the VAV unit. The VAV control uses a
valid control range of 45 to 70 F, and the potentiometer has
a valid range of −22 to 70 F. If the set point is between −22
and 45 F, the control will use a value of 45 F. If the set point
is outside the valid range (less than −22 F or greater than
70 F), an alarm condition will be signaled and a default value
of 70 F will be used.
DIP SWITCH NO. 3 — Economizer option. If economizer
option has been installed, this switch will be ON. If there is
no economizer installed, this switch will be OFF. Confirm
setting per Table 10. Change only if in error.
DIP SWITCH NO. 4 — Morning Warm-Up. For 48FK,JK
models, this switch will be ON (morning warm-up enabled).
For 50FK,JK units with factory-installed electric heaters, this
switch will be ON. For all other units, this switch will be
OFF. If accessory electric heaters are installed (for 50FK,JK
without plenum option), change this switch to ON.
ECONOMIZER MINIMUM POSITION (P5) — This po-
tentiometer specifies the minimum opening position for the
optional economizer during running periods. It has both a
valid range and an operational range of 0 to 100%.
DIP SWITCH NO. 5 — Demand Limit. Factory setting is
OFF (demand limit not enabled). If Demand Limit (single-
step or 2-step accessory) has been installed, change this switch
to ON.
SASP RESET TEMPERATURE (P7) — This potentiometer
establishes the space temperature at which the control will
initiate the reset of the SASP (i.e., the unit control begins to
raise the base SASP, to prevent overcooling of the space).
The potentiometer has a valid range of 40 to 100 F. Refer to
Space Temperature Reset section on page 16 for further dis-
cussion of SASP Reset operation.
DIP SWITCHES NO. 6 AND NO. 7 — Unloader Configu-
ration. These are factory set to match unit size. Confirm set-
tings per Table 12. Change only if in error.
RESET LIMIT (P3) — Used in conjunction with P7 poten-
tiometer, this potentiometer establishes the maximum tem-
perature for the modified SASP value during the Reset func-
tion. This potentiometer has a valid range of 0° to 80 F.
Table 12 — DIP Switches
SWITCH
NO.
SWITCH
FUNCTION
MEANING
POSITION*
DEMAND LIMIT, SINGLE-STEP (P4) — This potentiom-
eter establishes the maximum amount of compressor capac-
ity permitted by the unit control when single-step demand
limit operation is implemented (by closing contact set to po-
tentiometer wiper arm). This potentiometer is field-supplied
and -installed and will be located in the main control box.
The valid range is 0% to 100%, which is also the operational
range.
Reset
Mode
Space or Outdoor-Air Reset
(DO NOT CHANGE)
1
2
3
4
5
Off
Reset
Select
On
Off
Reset Used
Reset Not Used
On
Off
Enable Economizer
Disable Economizer†
Economizer
Morning
Warm-Up
On
Off
Enable Morning Warm-Up**
Disable Morning Warm-Up**
Demand
Limit
On
Off
Enable Demand Limit
Disable Demand Limit
If the wiper arm is open, all capacity stages can be used.
When the wiper arm is closed, the capacity is reduced by the
amount set on potentiometer P4.
Off, Off
On, Off
Off, On
No Unloaders
1 Unloader
2 Unloaders
6,7
8
Unloaders
Not Used
Off
No Significance
DEMAND LIMIT, 2-STEP — The accessory 2-step
demand limit control is a 2-potentiometer system. The
demand limit control board (DLCM) accessory board is
field-installed in the main control box; the 2 control poten-
tiometers are located on the DLCM. Potentiometer DLCM-P1
establishes the maximum amount of compressor capacity avail-
able when SW1 is closed and has a valid range is 50% to
100%. Potentiometer DLCM-P2 establishes the maximum
amount of compressor capacity available when SW2 is closed
and has a valid range is 0% to 49%.
If no power is supplied to the DLCM, all capacity stages
can be used. When power is supplied to terminal IN1 only,
the first step of demand limit control is energized and the
capacity is reduced by the amount set on potentiometer P1.
When power is supplied to IN2 (or IN1 and IN2), the ca-
pacity is reduced by the amount set on potentiometer P2.
LEGEND
Dual, In-Line Package
DIP
—
*Control circuit breaker must be off before changing the setting of the DIP switch.
†No economizer.
**And/or electric heat (50FK,JK units without plenum only).
Adjusting Set Points — Set points for unit operation
are established via potentiometer settings. Set points for Sup-
ply Fan controls are set at the VFD keypad (if installed) or
at the IGV differential pressure switch (DPS1) (if IGV op-
tion installed). Set points for modulating power exhaust (op-
tion or accessory) are set at the differential pressure switch
(DPS2).
MORNING WARM-UP (P6) — This potentiometer estab-
lishes the set point temperature for the Morning Warm-Up
function. This is the temperature at which the morning warm-up
sequence is terminated and VAV cooling operation begins.
The valid control range is 0° to 95 F, but the control is pro-
grammed to accept a range of 40 to 80 F. If the set point is
between 0° and 40 F, the control will use a value of 40 F.
If the set point is between 80 and 95 F, the control will use
a value of 80 F. If the set point is outside the valid range
(less than 0° F or greater than 95 F, an alarm condition will
be signaled and a default value of 40 F will be used.
Potentiometers — All of the set point potentiometers
must be set before the unit is started in order for the unit to
function properly. Each of the potentiometers has a valid range
that is used by the control. The valid range is defined as the
potentiometer’s resistance value that the control will not con-
sider to be in error. This is usually between 10% and 90%
of the potentiometer’s total resistance. The control has been
programmed to accept an operational range for the poten-
tiometer, which may not be the same as the valid range.
27
Supply Fan Control with IGV Option — The inlet
guide vane option will modulate the supply fan airflow in
order to maintain the static pressure in the supply duct. The
set point for duct static pressure is established at the differ-
ential pressure switch for the IGV control.
SIZE 034-048 UNITS — The inlet guide vane differential
pressure switch is located in the auxiliary control box mounted
in the corner under the side air hood that is next to the access
door marked FILTER SECTION. To gain access to this con-
trol box, remove the auxiliary control box cover. When
replacing cover, be sure to properly secure it in order to
prevent water from being drawn into the unit. See Fig. 36
and 37.
SIZE 054-104 UNITS — The inlet guide vane differential
pressure witch is mounted on an upright located behind the
supply-fan motor. See Fig. 36-38.
The IGV differential pressure switch has an adjustable
set point range of 1.1 to 3.5 in. wg. and a factory setting of
1.9 in. wg.
*The inlet guide vane differential pressure switch for the 034-048 units
is located in the back of the unit in the auxiliary control box. Its lo-
cation is not shown in this figure.
Fig. 36 — Inlet Guide Vane Motor,
50FK,JK034-074 Units
To adjust set point, turn set point adjusting screw (see
Fig. 39) clockwise to decrease set point and counterclock-
wise to increase set point. This switch also has an adjustable
null span. The null span is the pressure change that can be
made without contacts opening or closing. It is adjustable
from 0.06 in. wg to 0.17 in. wg when set point is at mini-
mum position (1.1 in. wg) and 0.11 in. wg to 0.31 in. wg
when set point is at maximum position (3.5 in. wg). To ad-
just null span, turn a null adjusting screw (Fig. 39) clock-
wise to decrease span and counterclockwise to increase span.
All switches leave factory with null span set at maximum
position. The smaller the null span, the closer the pressure
will be maintained to desired set point.
Supply Fan Control with VFD Option — The VFD
option will modulate Supply Fan motor (and thus wheel) speed
to maintain the static pressure in the ductwork. Set point for
the VFD option is set at the VFD, using the display key-
board on the front of the VFD enclosure. See Fig. 40.
NOTE: The VFD will always provide the proper phase
sequence to the supply-fan motor. The supply-fan motor op-
erates in proper rotation regardless of the phase sequence to
the unit. If, upon start-up, the outdoor fans operate back-
wards but the supply fan operates in the correct direction,
reverse any two leads to the main terminal block. All fans
will then operate in the correct direction.
*The inlet guide vane differential pressure switch for the 034-048 units
is located in the back of the unit in the auxiliary control box. Its lo-
cation is not shown in this figure.
Fig. 37 — Inlet Guide Vane Motor, 48FK,JK, 50FY,JY,
and 50FJX,FJY,FKX,FKY034-074 Units
To set the duct static pressure, perform the following steps.
The factory setting is 2.5 in. wg. The duct transducer has
a range from 0 to 5 in. wg. The transducer output is 4 to
20 mA, therefore, 0 to 5 in. wg is proportional to the 4 to
20 mA and must be expressed to the VFD in terms of per-
centage of the frequency range. Refer to Table 13. The set
point value is a percentage of the maximum output fre-
quency. Locate the duct static pressure closest to that de-
sired and use the corresponding set point value. If necessary,
interpolation between duct static pressures is permissible.
Factory-installed optional VFD is located near the sup-
ply fan and motor. During any service work or pro-
gramming at the VFD, operation of the fan and motor
is not desirable and may be dangerous. Either disable
the unit supply fan (following instructions below) or in-
stall the accessory VFD remote display accessory.
Fig. 38 — Inlet Guide Vane Motor,
Size 078-104 Units
28
ADJUST VFD SET POINT — To adjust the VFD set point,
the VFD must be powered; however, since it is located near
the supply fan and motor, operation of the fan and motor is
not desirable. Either disable the Supply Fan or install the
accessory VFD remote display accessory.
CAPACITOR
NULL
ADJUSTMENT
COM
N.C.
N.O.
DISABLE SUPPLY FAN MOTOR — To disable the supply
fan motor and change programming of VFD set point:
1. Turn off Indoor Fan Circuit Breaker (IFCB). This will
remove power to the VFD.
2. Wait for the VFD display to go blank and remove VFD
cover without touching any interior components.
3. Ensure that the charge indicator lamp is out which in-
dicates that the VFD is discharged. The lamp is located
on the upper right hand corner of the terminal block. If
still lit, wait until lamp goes completely out. This may
take several minutes.
4. Remove jumper from terminals ST-CC (see Fig. 41) and
replace VFD cover.
5. Turn on IFCB.
6. The drive output will now be disabled but the program-
ming can be changed.
SET
POINT
ADJUSTMENT
SET
POINT
INDICATOR
LEGEND
COM
N.C.
N.O.
—
—
—
Common
Normally Closed
Normally Open
Fig. 39 — Differential Pressure Switch for Inlet Guide
Vane and Static Pressure Control Option and
Modulating Power Exhaust Option
7. Change VFD set point according to Table 14 shown
below.
8. Once the program changes are completed, turn off IFCB.
9. Wait for the VFD display to go blank and remove VFD
cover without touching any interior components.
10. Ensure that the charge indicator lamp is out which in-
dicates that the VFD is discharged. The lamp is located
on the upper right hand corner of the terminal block. If
still lit, wait until lamp goes completely out. This may
take several minutes.
HZ
PERCENT
SECONDS
KW/AMPS/VOLTS
11. Replace jumper to terminals ST-CC.
12. Replace VFD cover.
13. Turn on IFCB to enable the drive.
For additional information on the VFD (including basic
troubleshooting, factory jumper arrangements, and Carrier
factory defaults programming), refer to Troubleshooting, Vari-
able Frequency Drive section (page 52).
SETUP
PROGRAM
MONITOR
RUN
READ
STOP
WRITE
RESET
IMPORTANT: The Carrier factory default values for
the VFD may be different than the default values of
the manufacturer. Refer to the Service section when
checking default values.
MANUAL/AUTO
LOCAL/REMOTE
RUN MODE
SPEED CTRL
Fig. 40 — Variable Frequency Drive Keypad
DETERMINE VFD SET POINT — The unit of measure for
the Duct Pressure set point at the VFD is output frequency
(Hz), representing the desired DP set point (DPSP) in inches
of water gage (in. wg). To convert desired DPSP into the
VFD set point, refer to Table 13. Locate the pressure value
in the table closest to the desired DPSP for this installation
and use the corresponding VFD set point (Hz) value. If nec-
essary, interpolation between duct static pressure values is
permissible.
P24 RES RR
F
R
S1 S2 S3 S4 RCH P24 LOW LOW
CC RX PP IV FP FLC FLB FLA
ST
FM AM CC
REMOVE
JUMPER
Fig. 41 — Jumper Removal to Disable Motor
29
Table 13 — VFD Set Point (Frequency Command) for Duct Pressure
PRESSURE
(in. wg)
CONTROL SIGNAL
(mA)
PRESSURE
(in. wg)
VFD SET POINT
(Hz)
CONTROL SIGNAL
(mA)
VFD SET POINT (Hz)
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
0
3
4.0
4.8
5.6
6.4
7.2
8.0
8.8
9.6
2.00
2.25
2.50
2.75
3.00
3.25
3.50
24
27
30
33
36
39
42
10.4
11.2
12.0
12.8
13.6
14.4
15.2
6
9
12
15
18
21
Table 14 — Changing the VFD Set Point (Frequency Command)*
KEY OPERATION
LED MESSAGE
EXPLANATION
Standard Monitor Mode (output frequency). If drive is disabled, display
will read ЉOFFЉ. If enabled, display will show current output frequency
XX.X or OFF
↓
↓↑
60.0
Pressing arrow key once will display the current frequency setpoint
Pressing up/down arrow keys changes the desired setpoint
45.0 (flashing)
When R/W is pressed, the parameter name (FC) and the new value
(45.0) will alternately flash to indicate that the new value has been
stored. After 2 cycles, the display will return to the standard monitor
mode.
R/W
FC and 45.0 (flashing)
XX.X or OFF
Standard Monitor Mode (output frequency). If drive is disabled, display
will read ЉOFFЉ. If enabled, display will show current output frequency
*Choose set point from Table 13 according to desired duct pressure.
DIFFERENTIAL PRESSURE SWITCH — The modulating
power exhaust DPS has a set point range of 0.5 in. wg to
−0.5 in. wg. Factory setting is +0.1 in. wg. To adjust set point,
turn set point adjusting screw (see Fig. 39) clockwise to
decrease set point and counterclockwise to increase set point.
This switch also has an adjustable null span. The null span
is the pressure change that can be made without contacts
opening or closing. It is adjustable from 0.06 in. wg to
0.14 in. wg when set point is at minimum position
(−0.5 in. wg) and 0.07 in. wg to 0.14 in. wg when set point
is at maximum position (+0.5 in. wg). To adjust null span,
turn null adjusting screw (Fig. 39) clockwise to decrease span
and counterclockwise to increase span. All switches leave
factory with null span set at maximum position. The smaller
the null span, the closer the pressure will be maintained to
desired set point.
Modulating Power Exhaust (Option or Acces-
sory) — The Modulating Power Exhaust system will main-
tain space pressure by modulating power exhaust fan no. 1
and staging power exhaust fan no. 2. Building pressure set
point is established at the modulating power exhaust differ-
ential pressure switch (DPS).
SIZE 034-048 UNITS — The modulating power exhaust dif-
ferential pressure switch is located in the auxiliary control
box mounted in the corner next to the power exhaust motor
door. To gain access to this control box, remove the auxil-
iary control box cover. When replacing cover, be sure to prop-
erly secure it in order to prevent water from being drawn
into the unit. See Fig. 33.
SIZE 054-104 UNITS — The modulating power exhaust dif-
ferential pressure switch is mounted below the auxiliary con-
trol box next to the access door labeled FILTER SECTION.
See Fig. 35.
30
For each step of the 33-step program, display button must
be pressed twice. On first press, step number is displayed;
second press initiates required action and appropriate code
is displayed.
NOTE: The step number is a numeral followed by a decimal
point (a 2-digit number has a decimal point after each nu-
meral). The action code number is one or 2 digits with no
decimal point(s).
START UNIT
To start unit:
1. Close the unit-mounted ON/OFF switch (located in the
main control box).
2. Close the field-supplied and -installed timeclock (or con-
trol) switch (contacts located at Terminals 1 and 2 (TB3
for 034-048, TB4 for 054-104).
IMPORTANT: The field-supplied and installed switch
(or timeclock) MUST BE CLOSED to put unit in
Occupied mode. Unit WILL NOT START until this
is accomplished.
IMPORTANT: Once quick test is initiated, display but-
ton must be pressed at least once every 10 minutes for
control to remain in quick test mode. If button is not
pressed within this time, control will attempt to start
the unit.
3. Initialization mode begins (see Operating Information sec-
tion on page 34 for complete description of sequences
and display codes).
4. Run Quick Test. If the display button is pressed during
the initialization mode period, the unit will run its self-
To recheck any step in quick test program, control must
be recycled by turning unit control switch off for a few sec-
onds, and then turning it back on again. Restart quick test
program as described above and proceed through quick test
steps. Press display button twice for each step until step to
be rechecked is reached.
diagnostic routine. When this is in effect, an 88 will ap-
pear in the display screen. Refer to Quick Test Program
section below, for instructions on completing the Quick
Test program.
The quick test program is divided into 3 sections as de-
scribed below and shown in Tables 15-17.
1. Quick Test Steps 1.-1.3. — Unit Configuration and Switch
Check
Quick Test Program — Turn on power to unit.
IMPORTANT: The field-supplied switch (or time-
clock) must be closed to put unit into the occupied mode.
The microprocessor in unit control system is programmed
by 2 switch assemblies located on processor board
(Fig. 1). The configuration header is factory set and can-
not be changed in the field. The DIP switch assembly con-
tains 8 microswitches that must be set in accordance with
the various options selected by the customer. All DIP
switches should be checked and set to proper position for
options selected prior to the quick test. See Configuration
of Header and DIP Switch Assembly section on page 5
for factory switch settings. The DIP switch functions and
display codes are shown in Table 15.
The quick test program utilizes the 2-digit LED display
(see Fig. 6) on the set point board to show status of all input
and output signals to microprocessor. Display action and quick
test procedures are described below.
The quick test program is a 33-step program that provides
a means of checking all input and output signals of controls
prior to unit start-up. This check ensures that all control op-
tions, thermistors, and control switches are in proper work-
ing order.
2. Quick Test Steps 1.4.-2.3. — Thermistor and Set Point
Potentiometer Check
When unit control circuit is switched to Occupied mode,
a 20 will appear on the display. Immediately press display
button once. An 88 will appear on the display and alarm
In these steps, the microprocessor checks resistance val-
ues of all sensors and set point potentiometers to ensure
that they are functional, connected properly, and set within
proper range for unit configuration.
Nominal resistance values for all sensors range from 363,000
to 219 ohms in accordance with Table 18. Normal dis-
play code for good sensors and potentiometers is 1. A dis-
play code of 0 indicates a faulty potentiometer, thermistor
or wiring. A 0 display also indicates that option is not
being used.
light on display board will be energized. This indicates that
control system is ready to run quick test program.
IMPORTANT: Do not allow unit control circuit to
remain energized with 20 showing on display for more
than 2 minutes. If display button is not pressed within
this time period, control will attempt to start unit.
Table 16 shows thermistor and set point potentiometer
functions and quick test display codes.
31
Table 15 — Quick Test, Unit Configuration and Switch Check
QUICK
TEST
NORMAL
DISPLAY
DESCRIPTION
CONTROL SWITCH
STEP NO.
1.
2.
3.
01
2
Type Unit — Air-Cooled VAV
No. of Compressors
Configuration Header
Configuration Header
DIP Switch No. 6 and 7
No. of Unloaders
(034,038,048-088)
2
1
(044, 104)
4.
5.
60
60-Hertz Power
Configuration Header
DIP Switch No. 2
0 — No Reset (Switch Off)
1 — Reset On (Switch On)
0
0
0
0
or
or
or
or
1
1
1
1
0 — No Economizer (Switch Off)
1 — Economizer On (Switch On)
DIP Switch No. 3
DIP Switch No. 4
DIP Switch No. 5
6.
7.
8.
0 — No Warm-Up (Switch Off)
1 — Warm-Up Used (Switch On)
0 — Demand Limit Not Used
(Switch Off)
1 — Demand Limit Used
(Switch On)
0 — Enthalpy Switch Open
1 — Enthalpy Switch Closed
EC
9.
0
or
1
1
1 — Low-Pressure Switch Closed
1 — Low-Pressure Switch Closed
No Circuit 1 Oil Pressure Switch
No Circuit 2 Oil Pressure Switch
Low-Pressure Switch 1
Low-Pressure Switch 2
None*
1.0.
1.1.
1.2.
1
1
1.3.
1
None*
LEGEND
DIP
EC
VAV
—
—
—
Dual, In-Line Package
Enthlapy Control
Variable Air Volume
*Units are not equipped with oil pressure switches.
32
Table 16 — Quick Test, Thermistor and Potentiometer Check
QUICK
TEST
STEP NO.
NORMAL
DISPLAY
THERMISTOR OR
POTENTIOMETER*
DESCRIPTION
1 — Thermistor OK
0 — Thermistor Faulty
Supply Air
Thermistor (T1)
1.4.
1.5.
1.6.
1.7.
1
1
1
1
1 — Thermistor OK
0 — Thermistor Faulty
Return Air
Thermistor (T2)
1 — Thermistor OK
0 — Thermistor Faulty
Circuit 1 Condenser Thermistor
(T3)
1 — Thermistor OK
0 — Thermistor Faulty
Circuit 2 Condenser Thermistor
(T4)
1 — Thermistor or Potentiometer OK
0 — Thermistor or Potentiometer Faulty or
Option not used
Accessory Space Temperature Thermistor (T10)
or Accessory Reset Potentiometer (P7)
1.8.
1
1 — Potentiometer OK
0 — Potentiometer Faulty
Supply-Air Set Point
Potentiometer (P1)
1.9.
2.0.
2.1.
1
1
1
1 — Potentiometer OK
0 — Potentiometer Faulty or Option not used
Accessory Reset Limit
Potentiometer (P3)
1 — Potentiometer OK
0 — Potentiometer Faulty or Option not used
Accessory Demand Limit
Potentiometer (P4)
Minimum Position
Economizer
Potentiometer (P5)
1 — Potentiometer OK
0 — Potentiometer Faulty or Option not used
2.2.
2.3.
1
1
1 — Potentiometer OK
0 — Potentiometer Faulty or Option not used
Warm-Up Set Point
Potentiometer (P6)
*Potentiometer P2 is not listed since it is not part of the quick test. If on unit start-up a Code 83 is displayed, check potentiometer P2.
Table 17 — Quick Test, Output Relay Check
QUICK
TEST
STEP NO.
NORMAL
DISPLAY
DESCRIPTION
RELAY NUMBER
2.4.
2.5.
1
1
1 — Open Economizer or Open Relay if no Economizer
1 — Close Economizer or Close Relay if no Economizer
1 — Energize Fan Relay and Heat Relay
Energize Stage 1 Condenser Fan(s)
Energize Stage 2 Condenser Fan(s)
Energize Compressor 1†
K7
K8
K9* and K10
2.6.
2.7.
1
1
K11
K12
K1
2.8.
2.9.
1
0
0
then
1
0
0
1
0
then
0
0
3.0.
Energize Unloader 2; Not Used (044, 104)
Energize Unloader 1
K2
3.1.
K3
3.2.
then
then
Energize Compressor 2†
K5
3.3.
Not Used
K6
LEGEND
CR
—
Control Relay
*K9 (fan relay) will remain on for duration of quick test.
†Compressor will be energized for 10 seconds. Zero indicates open CR; 1 indicates closed CR.
33
Table 18 — Sensor Resistance Values
load if the outdoor enthalpy is good. As long as the outdoor-
air enthalpy is acceptable, no mechanical cooling will take
place until the economizer dampers are fully open. The rest
of the steps and the operational sequence vary due to the
number of compressors and unloaders. Refer to Operating
Sequence section on page 35 for the unit stages of operation.
TEMP RESISTANCE TEMP RESISTANCE TEMP RESISTANCE
(F)
(Ohms)
(F)
(Ohms)
(F)
(Ohms)
−60
362,640
297,140
245,245
202,841
168,250
139,960
116,820
98,420
82,665
69,685
58,915
50,284
42,765
36,475
31,216
26,786
23,164
19,978
17,276
14,980
13,085
45
50
55
60
65
70
75
80
85
11,396
9,950
8,709
7,642
6,749
5,944
5,249
4,644
4,134
3,671
3,265
2,913
2,600
2,336
2,092
1,879
1,689
1,527
1,377
1,244
1,126
150
155
160
165
170
175
180
185
190
195
200
205
210
215
220
225
230
235
240
1,020
929
844
768
699
640
585
535
490
449
414
380
350
323
299
276
255
236
219
−55
−50
−45
−40
−35
−30
−25
−20
−15
−10
−5
CODES 20 THROUGH 30 AND 88, OPERATIONAL STA-
TUS — These codes indicate special operational modes, such
as initialization, morning warm-up, temperature reset, de-
mand limit, or an internal failure of the board. Codes 23-25
and 27-29 are not used on these units.
90
95
Initialization — When the control is turned on, the display
100
105
110
115
120
125
130
135
140
145
0
5
shows a
for approximately 2 minutes to indicate that the
20
10
15
20
25
30
35
40
control is in the initialization mode. During this time, the
economizer dampers open and close to determine the resis-
tance range of the economizer position potentiometer (P2)
for full economizer operation. The processor loads the nec-
essary constants for proper unit operation and checks the ther-
mistors and other potentiometers for their values and valid-
ity. After the initialization period, the display screen goes
blank until the display button is pressed. If the display but-
ton is pressed during the 2-minute initialization period, the
control goes into the Quick Test mode.
3. Quick Test Steps 2.4.-3.3. — Output Relay Check
Temperature Reset — If the unit is equipped with the ac-
cessory temperature reset package, and DIP switch 2 is in
the ON position, the unit will reset the supply-air tempera-
ture to a calculated value when necessary. When this con-
These quick test steps allow microprocessor to check
output signals from relay boards in unit control system. In ad-
dition, operation of all the condenser fans, compres-
sors, and economizer (if equipped) are checked at each step.
dition is in effect, a
will appear in the display.
21
Normal display for Steps 2.4. through 2.8. is 1. In Steps
2.9. through 3.2., each compressor and unloader is started
and allowed to run for approximately 10 seconds. At start-
up, a 0 will appear on the display followed by a 1 (Steps
2.9. and 3.2.) in a few seconds. Steps 3.0. and 3.1. will
always be 0 since there are unloaders, and Step 3.3. will
always be zero since it is not used.
At end of the 10-second time period, a 0 will return to the
display board indicating that test step has been success-
fully completed (Steps 2.9. and 3.2.). The 1 indicates that
was tested.
Demand Limit — If the unit is equipped with the accessory
demand limit control module or the field-supplied, single-
step demand limit potentiometer, and DIP switch 5 is in the
ON position, the unit will limit the capacity stages to a pre-
determined value. When this condition is in effect, a
appear in the display.
Morning Warm-Up —If the morning warm-up heat routine
is enabled using DIP switch 4, and conditions of the occu-
pied space warrant, the unit will begin the morning warm-up
routine. When this condition is in effect, a
in the display.
will
22
will appear
26
Fan and compressor operating sequence for quick test
Steps 2.4. through 3.3. are shown in Table 17.
Internal Failure — If the unit detects an internal fault (such
as a time measurement failure), or detects an incorrect volt-
If the quick test steps do not operate as described above,
a defect exists in one or more of the following: relay being
tested, electronic control, or unit wiring. Determine problem
and correct.
age on an input channel, a
unit will shut down.
will be displayed, and the
30
Quick Test — If the display button is pressed during the
initialization period of the processor, the unit will run its self-
OPERATING INFORMATION
diagnostic routine. When this is in effect, an
in the display screen.
will appear
88
Digital Display — The VAV control system uses a 2-digit
LED display located on the display board to display opera-
tional information and diagnostic codes.
CODES 51 THROUGH 87, DIAGNOSTIC INFORMA-
TION — These codes indicate diagnostic information when
there is a unit problem such as a faulty thermistor, potenti-
ometer, or compressor fault. Refer to Diagnostic Codes sec-
tion on page 45 for more details. Codes 53, 54, 57, 58, 61,
62, 65-69, 73, 74, and 77-80 are not used on these units.
CODES 0 THROUGH 8, CAPACITY STEPS — These codes
indicate the number of cooling stages active at the time the
display button is pressed. The highest code indicated on the
display will be 6 for the 034,038 and 048-088 units, 4 for the
044 units, and 8 for the 104 units.
Under normal operation, only the stage number is dis-
played when the display button is pressed. If a status or over-
load code is displayed, the display will rotate every 2 sec-
onds and will display up to 3 codes. Overload information
takes priority over all other codes. The codes are stored in
the microprocessor as long as the board remains energized.
Capacity steps are directly related to pin terminal connec-
tor J6 output. At step zero, the unit has no mechanical cool-
ing on, and the economizer may or may not be operating
(depending on the outdoor air conditions). Once a cooling
load is detected (T1 thermistor reads above the supply-air
set point), the economizer will begin modulating to meet the
34
Compressors, unloaders, and condenser fans will be cycled
to maintain a supply-air temperature 2° F below the poten-
tiometer P1 set point once the mechanical cooling stages be-
gin. Each unit’s cycling is slightly different, and is based on
the number of compressors and unloaders. The operational
loading sequence of compressors is as follows:
During the start-up of the lead compressor for each cir-
cuit, the low-pressure switch will be bypassed for 120 sec-
onds to prevent nuisance trips of the low-pressure switch.
After start-up, a low-pressure trip will be ignored for 30 sec-
onds by the processor.
Operating Sequence — The sequence presented be-
low assumes that the unit is equipped with heat for morning
warm-up and an economizer. If these items are not enabled
with the appropriate DIP switches, the processor bypasses
these subroutines. This sequence is also based on an EPROM
(erasable, programmable, read-only memory) processor chip
with the identification ‘HT204485-1-XX,’ where ‘XX’ is re-
placed by a 2-digit number representing the current software
version. See Fig. 1 for EPROM chip location.
When power is applied to the occupied mode relay (OMR)
through the closure of either a field-installed timeclock or a
field-installed switch in the occupied space, the unit will be-
gin its initialization mode.
SIZE 034,038 AND 048-088 UNITS — These units have 2
compressors and 2 unloaders on compressor 1. See Fig. 42
and 43 for compressor and condenser-fan motor locations.
The operating sequence is as follows:
20
A
will appear in the display screen, and the initial-
ization period will last approximately 2 minutes. During this
time, the economizer dampers open and close to determine
the resistance range for full economizer operation of the econo-
mizer position potentiometer (P2). The processor loads the
necessary constants for unit operation, and also checks the
thermistors and other potentiometers for their values and va-
lidity. After the initialization period, the screen goes blank
until the display button is pressed.
Stage 1 Relays K1, K2, and K3 are energized. Compressor
no. 1 starts with both unloaders energized. Com-
1
pressor no. 1 runs at ⁄3 capacity. The crankcase
heater for this compressor has been deenergized,
and the first stage of condenser fans have been en-
ergized. Outdoor (condenser) fan motor no. 1
(OFM1) has started on all units.
Stage 2 Relays K1 and K3 are energized. Compressor
no. 1 is running with unloader 1 (U1) energized.
2
The compressor is now operating at ⁄3 capacity.
Use caution during this time (after initialization when
the screen is blank), because the unit supply and return
fans could start at any time. Personal injury could result
from contact with rotating fans.
Stage 3 Relay K1 is energized. Compressor no. 1 is fully
loaded.
Stage 4 Relays K1, K2, K3, and K5 are energized. Com-
1
pressor no. 1 is running at ⁄3 capacity, and com-
Once the initialization period is complete, the supply fan
begins operation. While the fan is operating, the economizer
dampers are closed and return air from the building is being
circulated. After 2 minutes, the processor checks the resis-
tance value of thermistor T2. If T2 temperature sensed is
5° F or more below the set point of the morning warm-up
potentiometer (P6), the unit will begin the morning
pressor no. 2 is running at full capacity. The crankcase
heater for compressor no. 2 has been deenergized.
Stage 5 Relays K1, K3, and K5 are energized. Compressor
2
no. 1 is running at ⁄3 capacity, and compressor
no. 2 is running at full capacity.
Stage 6 Relays K1 and K5 are energized. Both compres-
sors are running fully loaded.
warm-up routine, and a 26 will be displayed.
Size 034 and 038 units have 2 condenser fans, one of which
is controlled by the microprocessor. The OFM1 is energized
with compressor no. 1. The OFM2 is controlled by the pro-
cessor and is cycled based on input from circuit thermistor
T3 or T4.
Size 048 units have one fan that can be controlled by the
processor. The other 2 are controlled by the compressors.
The OFM1 is energized by compressor no. 1, and OFM3 is
energized by compressor no. 2. The OFM2 is cycled by the
processor based on input from either circuit (thermistors T3
and T4).
Unit heat will be energized through the heat interlock re-
lay (HIR), and all of the occupied space air terminals open.
The unit will continue heating the space until the return-air
temperature is within 2° F of set point. The unit will then
shut off the heat and continue to circulate air. The unit will
cycle in and out of the heating mode until the return-air tem-
perature reaches the morning warm-up set point (P6). Once
morning warm-up has been terminated, the unit cannot re-
turn to morning warm-up until the unit is powered down and
restarted. This action signals a return to the Occupied mode.
NOTE: Occupied heat is NOT AVAILABLE on these units.
On size 054,064 units, the first 2 condenser fans energize
with the compressors; compressor no. 1 controls OFM1, and
compressor no. 2 controls OFM2. The OFM3 and OFM4 are
staged by the microprocessor based on the condensing tem-
perature input from thermistor T3 or T4.
On size 074-078 units, the first 3 condenser fans energize
with the compressors; compressor no. 1 controls OFM1, and
compressor no. 2 controls OFM2 and OFM3. The OFM4
and OFM5 are staged by the microprocessor based on con-
densing temperature input from either circuit’s T3 or T4
thermistor.
On Size 088 units, the first 4 condenser fans energize with
the compressors; compressor no. 1 controls OFM1 and OFM3,
and compressor no. 2 controls OFM2 and OFM4. The OFM5
and OFM6 are staged by the microprocessor based on
condensing temperature input from either circuit’s T3 or T4
thermistor.
Once out of the morning warm-up routine, the unit will
begin its cooling routine based on the supply-air set point
(P1). At step zero, the unit has no mechanical cooling on,
and the economizer may or may not be operational. The econo-
mizer will move to the minimum position determined by po-
tentiometer P5 if no cooling load is detected. Once a cooling
load is detected by thermistor T1 sensing a temperature higher
than the cooling demand set point (P1), the economizer will
begin modulating to meet the load if the outdoor enthalpy is
good. The processor will attempt to maintain a supply-
air temperature of P1 ± 2° F by modulating the economizer
dampers.
No mechanical cooling will take place until the econo-
mizer dampers are fully open (if the outdoor-air enthalpy
permits). If the economizer is unable to meet the cooling
demand, then mechanical cooling is used in conjunction with
the economizer. If the economizer is unable to meet the load
due to unacceptable outdoor-air enthalpy, the dampers will
return to the minimum position as determined by P5.
35
SIZE 044 UNITS — These units have 2 compressors and 1
unloader on compressor no. 1. See Fig. 42 for compressor
and condenser fan motor locations. The unit operating se-
quence is as follows:
Stage 1 Relays K1 and K3 are energized. Compressor
no. 1 starts with the unloader energized. Com-
pressor no. 1 is running at 1⁄2 capacity. The crank-
case heater on compressor no. 1 has been deen-
ergized, and the first stage condenser fan has been
energized. Outdoor (condenser) fan motor no. 1
(OFM1) has started.
Stage 4 Relays K1 and K5 are energized. Both compres-
sors no. 1 and no. 2 are running fully loaded.
Stage 5 Relays K1, K3, K5, and K5 are energized. Com-
pressor no. 1 runs at 2⁄3 capacity and compressors
no. 2 and no. 4 are running at full capacity. The
crankcase heater on compressor no. 4 is deener-
gized. Fans OFM1, OFM2, OFM3, and OFM4 are
operating.
Stage 6 Relays K1, K5, and K6 are energized. Compres-
sors no. 1, no. 2, and no. 4 are running fully loaded.
Stage 7 Relays K1, K2, K3, K5, and K6 are energized.
Stage 2 Relay K1 is energized. Compressor no. 1 is fully
loaded.
2
Compressor no. 1 runs at ⁄3 capacity and com-
pressors no. 2, no. 3, and no. 4 are running at full
capacity. Fans OFM1, OFM2, OFM3, and OFM4
are operating. Crankcase heater for compressor
no. 3 is deenergized.
Stage 3 Relays K1, K3, and K5 are energized. Compres-
1
sor no. 1 is running at ⁄2 capacity, and compres-
sor no. 2 is running at full capacity. The crankcase
heater for compressor no. 2 is deenergized. The
second stage condenser fan has been energized.
Both OFM1 and OFM3 are operating.
Stage 8 Relays K1, K2, K5, and K6 are energized. Com-
pressors no. 1, no. 2, no. 3, and no. 4 are running
fully loaded.
On Size 104 units, the first 4 condenser fans energize with
the compressors; circuit no. 1 compressors control OFM1
and OFM3, and circuit no. 2 compressors control OFM2 and
OFM4. The OFM5 and OFM6 are staged by the micro-
processor based on condensing temperature input from
either circuit’s T3 or T4 thermistor.
Stage 4 Relays K1 and K5 are energized. Both compres-
sors are running fully loaded.
Size 044 units have one fan that can be controlled by the
processor. The other 2 are controlled by the compressors.
The OFM1 is energized by compressor no. 1, and OFM3 is
energized by compressor no. 2. The OFM2 is cycled by the
processor based on input from either circuit (thermistors T3
and T4).
SIZE 104 UNITS — These units have 4 compressors and
1 unloader on compressor no. 1. See Fig. 43 for compressor
and condenser fan motor locations. The unit operating se-
quence is as follows:
Head Pressure Control — All units have as standard
a basic head pressure control function which allows the units
to operate in cooling down to 45 F. If cooling is required at
outdoor ambient temperatures lower than 45 F, refer to ac-
cessory head pressure control literature for details.
Head pressure control is handled by the processor. The
processor attempts to maintain the head pressure by cycling
the condenser-fan motors. No condenser fans will be run-
ning without a call for mechanical cooling. Thermistors T3
and T4 provide the condensing temperature information to
the processor. These VAV rooftop units have dual refrigera-
tion circuits, and the higher circuit temperature will govern
unit operation. If the condensing temperature is above
133 F (236 psig), a condenser fan stage will be added. If the
condensing temperature is 78 F (142 psig) or less, the num-
ber of condenser fans operating will be decreased. After each
fan stage, the processor will wait one minute for the head
pressures to stabilize before changing again, unless ther-
mistor T3 or T4 senses a temperature greater than 125 F
(278 psig), in which case all condenser fans are started.
Stage 1 Relays K1 and K3 are energized. Compressor
no. 1 starts with unloader energized. Compressor
no. 1 runs at 2⁄3 capacity. The crankcase heater for
this compressor has been deenergized, and first stage
of condenser fans has been energized. Outdoor (con-
denser) fan motor no. 1 (OFM1) and oudoor fan
motor no. 3 (OFM3) have started.
Stage 2 Relay K1 is energized. Compressor no. 1 is fully
loaded.
Stage 3 Relays K1, K3, and K5 are energized. Compres-
2
sor no. 1 runs at ⁄3 capacity and compressor
no. 2 is running at full capacity. The crankcase
heater for compressor no. 2 is deenergized. The
first stae of condenser fans on circuit 2 has been
energized. Fans OFM1, OFM2, OFM3, and OFM4
are operating.
During start-up, if the outdoor ambient is above 70 F (as
sensed by thermistor T3 or T4), the first-stage, processor-
controlled fans are turned on to prevent excessive discharge
pressures.
034 AND 038 UNITS
LEGEND
044 AND 048 UNITS
OFM
—
Outdoor (Condenser) Fan Motor
Fig. 42 — Component Arrangement, 034-048 Units
36
054, 064 UNITS
054-088 UNITS
074, 078 UNITS
088, 104 UNITS
104 UNITS
Fig. 43 — Component Arrangement, 054-104 Units
37
Supply Fan Control with IGV — In most VAV units,
the supply fan static pressure is controlled by inlet guide vanes.
The inlet guide vanes operate independently from the micro-
processor. The supply static pressure is controlled by a dif-
ferential pressure switch. If the unit is equipped with a re-
turn fan, building pressure is controlled by another differential
pressure switch.
Modulating Power Exhaust (Option or Acces-
sory except FY,JY units) — The power exhaust as-
sembly consists of two parallel and independent belt-drive
forward curve fans. The fans, motors, and drives are located
over the return air opening of the unit, in a plenum beneath
the outside air intake plenum. The fans discharge air hori-
zontally out the back of the unit through individual baro-
metric backdraft dampers with hoods. (See Fig. 44 and 45.)
Operation is interlocked with economizer operation. Sheet
metal installation is shown in Fig. 46 and 47.
Fan no. 1 is equipped with a variable position discharge
damper located in the outlet of the fan housing. This damper
is controlled by an actuator (PEDM), based on signals from
the building pressure differential pressure switch (DPS). Avail-
able range on the DPS is −0.50 to +0.50 in. wg, adjustable.
Building pressure is sensed by a pick-up (field-supplied and
-installed) located in the occupied space.
Operation of the modulating power exhaust is a combi-
nation modulating/staged control, with fan no. 1 providing
modulating control from 0 to 100%, and fan no. 2 being staged
On/Off according to damper position on fan no. 1.
As the economizer actuator opens past 17% open, auxil-
iary switch DMS1 closes, energizing fan contactor PEC1.
Fan motor no. 1 starts and runs.
Capacity of fan no. 1 is controlled by the position of the
outlet damper. As building pressure increases above set point,
the DPS will close its contact and drive the power exhaust
damper motor (PEDM) open until set point is achieved. DPS
then opens its control contacts and PEDM maintains current
position.
When space demand moves PEDM to 90% of full-open
position, auxiliary switch PEDMS closes, energizing fan con-
tactor PEC2. Fan motor no. 2 starts and runs. Increased ex-
haust airflow will lower space pressure, causing DPS to drive
PEDM back towards its closed position, until the set point
is achieved.
For example, assume that set point on supply fan differ-
ential switch is 1.9 in. wg. If pressure in supply duct goes
above 1.9 in. wg, switch will make to the normally open
contact and energize inlet guide vane motor to drive inlet
guide vanes to a more closed position, thus reducing airflow
and lowereing duct pressure. Once set point pressure is reached,
switch will open and deenergize inlet guide vane motor. If
pressure in supply duct is below 1.9 in. wg, the switch will
make to the normally closed contact and energize inlet guide
vane motor to drive inlet guide vane to a more open posi-
tion; increasing airflow and raising duct pressure. Once again,
once desired pressure has been reached, switch will open and
deenergize inlet guide vane motor. How far above or below
the set point setting the switch goes before energizing de-
pends on setting of null span (null span is pressure change
that can be made without contacts opening or closing). If
null span is at maximum position, pressure will vary from
0.17 in. wg to 0.31 in. wg depending on set point (if set point
is at minimum setting, null span will be 0.17 in. wg, while
if it is at maximum position, the null span will be
0.31 in. wg) before switch acts. If null span is adjusted to a
minimum setting, duct pressure will vary from 0.06 in. wg
to 0.11 in. wg (again depending on switch set point) before
switch acts. Setting null span to minimum position will re-
sult in a smaller pressure fluctuation than if it is set at maxi-
mum position.
Supply Fan Control with VFD — When equipped
with the VFD option, the supply fan static pressure is con-
trolled by modulating the fan wheel speed. The VFD oper-
ates independently from the microprocessor. A duct pressure
transducer monitors duct static pressure. The transducer out-
put (4 to 20 mA) is directed into the VFD. The VFD adjusts
supply fan motor speed (which changes wheel speed) as mea-
sured duct pressure varies from set point as established at
the VFD. The VFD will modulate fan speed until the duct
pressure set point is achieved.
If space pressure decreases until PEDM position is re-
duced to 10% of open position, PEDMS will open, deener-
gizing fan contactor PEC2 and shutting off fan no. 2.
Unit Staging — Compressor loading and unloading se-
quences are shown in Table 19.
NOTE: The VFD will always provide the proper phase se-
quence to the supply fan motor. This motor will operate in
proper rotation regardless of the phase sequence to the unit.
If, upon start-up, the outdoor fans operate backwards but the
indoor fan operates in the correct direction, reverse any two
leads to the main terminal block. All fans will then operate
in the correct direction.
38
Fig. 44 — Modulating Power Exhaust Component Locations; Sizes 034-048
39
40
Fig. 46 — Modulating Power Exhaust Return End Sheet Metal Skin Detail; Sizes 034-048
Fig. 47 — Modulating Power Exhaust Return End Sheet Metal Skin Detail; Sizes 054-104
41
Table 19 — Compressor Loading and Unloading Sequences
SIZE 034 UNITS
COOLING
STAGE
Lead Circuit
Lag Circuit
Active
Cylinders
Percent
Capacity
Unloader
U1
Unloader
U2
Comp 1
Comp 2
0
1
2
3
4
5
6
OFF
ON
ON
ON
ON
ON
ON
OFF
ON
OFF
ON
OFF
OFF
OFF
OFF
ON
0
2
0
17
ON
OFF
OFF
ON
4
33
OFF
ON
6
50
8
67
ON
OFF
OFF
ON
10
12
83
OFF
ON
100
SIZE 038 UNITS
COOLING
STAGE
Lead Circuit
Lag Circuit
Active
Cylinders
Percent
Capacity
Unloader
U1
Unloader
U2
Comp 1
Comp 2
0
1
2
3
4
5
6
OFF
ON
ON
ON
ON
ON
ON
OFF
ON
OFF
ON
OFF
OFF
OFF
OFF
ON
0
2
0
14
ON
OFF
OFF
ON
4
28
OFF
ON
6
42
6
72
ON
OFF
OFF
ON
8
86
OFF
ON
10
100
SIZE 044 UNITS
COOLING
STAGE
Lead Circuit
Unloader
Lag Circuit
Active
Percent
Cylinders
Capacity
Comp 1
Comp 2
U1
OFF
ON
0
1
2
3
4
OFF
ON
ON
ON
ON
OFF
OFF
OFF
ON
0
2
4
6
8
0
25
OFF
ON
50
75
OFF
ON
100
SIZE 048 UNITS
Lag Circuit
COOLING
STAGE
Lead Circuit
Active
Cylinders
Percent
Capacity
Unloader
U1
Unloader
U2
Comp 1
Comp 2
0
1
2
3
4
5
6
OFF
ON
ON
ON
ON
ON
ON
OFF
ON
OFF
ON
OFF
OFF
OFF
OFF
ON
0
2
0
19
ON
OFF
OFF
ON
4
38
OFF
ON
6
58
6
62
ON
OFF
OFF
ON
8
81
OFF
ON
10
100
42
Table 19 — Compressor Loading and Unloading Sequences (cont)
SIZE 054 UNITS
COOLING
STAGE
Lead Circuit
Lag Circuit
Comp 2
OFF
Active
Cylinders
Percent
Capacity
Comp 1
OFF
ON
Unloader U1
OFF
Unloader U2
OFF
0
1
2
3
4
5
0
2
0
20
ON
ON
OFF
ON
ON
OFF
OFF
4
40
ON
OFF
OFF
OFF
6
60
ON
ON
OFF
ON
10
12
80
ON
OFF
OFF
ON
100
SIZE 064 UNITS
COOLING
STAGE
Lead Circuit
Lag Circuit
Comp 2
OFF
Active
Cylinders
Percent
Capacity
Comp 1
OFF
ON
Unloader U1
OFF
Unloader U2
OFF
0
1
2
3
4
5
6
0
2
0
17
ON
ON
OFF
ON
ON
OFF
OFF
4
33
ON
OFF
OFF
OFF
6
50
ON
ON
ON
ON
8
67
ON
ON
OFF
ON
10
12
83
ON
OFF
OFF
ON
100
SIZE 074, 078 UNITS
COOLING
STAGE
Lead Circuit
Lag Circuit
Comp 2
OFF
Active
Cylinders
Percent
Capacity
Comp 1
OFF
ON
Unloader U1
OFF
Unloader U2
OFF
0
1
2
3
4
5
6
0
2
0
14
ON
ON
OFF
ON
ON
OFF
OFF
4
29
ON
OFF
OFF
OFF
6
43
ON
ON
ON
ON
8
71
ON
ON
OFF
ON
10
12
86
ON
OFF
OFF
ON
100
SIZE 088 UNITS
COOLING
STAGE
Lead Circuit
Lag Circuit
Comp 2
OFF
Active
Cylinders
Percent
Capacity
Comp 1
OFF
ON
Unloader U1
OFF
Unloader U2
OFF
0
1
2
3
4
5
6
0
2
0
16
ON
ON
OFF
ON
ON
OFF
OFF
4
33
ON
OFF
OFF
OFF
6
50
ON
ON
ON
ON
8
66
ON
ON
OFF
ON
10
12
83
ON
OFF
OFF
ON
100
SIZE 104 UNITS
Lag Circuit
COOLING
STAGE
Lead Circuit
Unloader U1
OFF
Active
Percent
Cylinders
Capacity
Comp 1
OFF
ON
Comp 3
OFF
OFF
OFF
OFF
OFF
OFF
OFF
ON
Comp 2
OFF
OFF
OFF
ON
Comp 4
OFF
OFF
OFF
OFF
OFF
ON
0
1
2
3
4
5
6
7
8
0
4
0
20
ON
ON
OFF
6
30
ON
ON
10
12
14
16
18
20
50
ON
OFF
ON
60
ON
ON
ON
70
ON
OFF
ON
ON
80
ON
ON
ON
ON
90
ON
OFF
ON
ON
ON
100
43
Table 21 — Operation Status Codes
TROUBLESHOOTING
By using the display module, actual operating conditions
of the unit are displayed while it is running. The Quick Test
function allows proper operation of compressors, compres-
sor unloaders, fans, and other components to be checked while
unit is stopped. If an operating fault is detected, an alarm is
generated and an alarm code(s) is displayed. For checking
specific items, see Table 20.
CODE
MEANING
0 cooling stages active
0
□
1
□
1 cooling stage active
2
□
2 cooling stages active
3 cooling stages active
Checking Display Codes — To view the digital dis-
play codes, press the button located to the right of the LED
display/set point board in the control box. See Table 21 for
Operational Status Codes. See Table 22 for Diagnostic Codes.
3
□
4
□
4 cooling stages active
5 cooling stages active
6 cooling stages active
7 cooling stages active
8 cooling stages active
5
□
Complete Unit Stoppage — If the unit is off, there
are several conditions that can cause this situation to occur:
• Remote ON/OFF circuit in Unoccupied mode.
• Unit ON/OFF switch moved to OFF position.
• Programmed schedule at the timeclock.
• General power failure.
• Blown fuse in the control power feed.
• Open control circuit fuse.
• Operation of the unit blocked by the demand limit
function.
6
□
7
□
8
□
Initialization mode (Allow 2 minutes
for initialization. To initiate Quick Test,
press the Display button while 20 is displayed.)
20
□
• Unit supply-air temperature (T1) thermistor failure.
• Supply-air fan is not operating.
• High duct static pressure.
21
□
Temperature Reset in effect
Demand Limit in effect
22
□
Single Circuit Stoppage — If a single circuit stops,
there are several potential causes:
26
□
Morning Warm-Up in effect
Internal failure detected
• Open contacts in the compressor high-pressure switch.
• Low refrigerant pressure.
30
□
• Thermistor failure.
• Unit supply-air temperature thermistor (T1) failure.
• Compressor circuit breaker trip.
• Operation of the circuit blocked by the demand limit
function.
88
□
Self-diagnostic mode in effect
Restart Procedure — Before attempting to restart the
machine, check the display for alarm codes to determine the
cause of the shutdown. If the unit, circuit, or compressor stops
more than once as a result of a safety device, determine and
correct the cause before attempting to start the unit again.
After the cause of the shutdown has been corrected, unit
restart may be automatic or manual depending upon the fault.
Table 20 — Controls Troubleshooting
SYMPTOM(S)
PROBABLE CAUSE(S)
SOLUTION(S)
Controls do not seem
to be operating.
Remote on-off function may be
keeping controls off.
Check status.
Evaporator fan does not run.
1. Circuit breaker open.
2. Inverter overload (if equipped).
1. Find cause and reset circuit breaker.
2. Find cause and reset.
Compressor does not run.
1. Circuit breaker is open.
1. Find cause and reset circuit breaker.
2. Correct operation.
2. There is no demand for cooling.
3. The control is locking out cooling operation.
3. Check rotating display for alarm codes. Resolve
alarm cause and reset control by changing to
standby and back to run mode.
4. Demand Limit in effect.
Circuit breaker is open.
4. Check Demand Limit Settings.
Condenser fans do not
turn on.
Find cause and reset circuit breaker
Cooling demand exists and
economizer modulates, but
compression is not operating.
Compression cannot be initiated
until economizer damper is 90% open.
Correct operation.
44
Code 51 is for compressor 1, and Code 55 is for com-
pressor 2. Codes 52 and 56 are used for compressors 3 and
4, respectively, on size 104 units.
The microprocessor has also been programmed to indi-
cate a compressor failure if CR switch is closed when com-
pressor is not supposed to be on.
Diagnostic Codes — Diagnostic codes are warnings
of abnormal or fault conditions, and may cause either one
circuit or the whole unit to shut down. They are assigned
code numbers as described below.
Table 22 contains a description of each diagnostic code
error and possible cause. Manual reset is accomplished by
moving the ON/OFF Switch to the OFF position, then back
to ON.
The 2-digit LED display is used to display the diagnostic
codes and the alarm light (located next to display) is ener-
gized whenever a diagnostic code is tripped. When a prob-
lem is suspected, always check the display first for diagnos-
tic information.
NOTE: Codes 53, 54, 57, 58, 61, 62, 65-69, 73, 74, and 77-80
are not used on these units.
If a failure occurs, the following are possible causes:
High-Pressure Switch Open — The high-pressure switch for
each compressor is wired in series with 24-v power that en-
ergizes CR. If high-pressure switch opens during operation,
CR will stop compressor and this will be detected by micro-
processor through the feedback contacts.
Internal Thermostat — The internal thermostat in each 06D
compressor is also wired in series with 24-v power that en-
ergizes CR. If thermostat fails or switch opens during op-
eration of compressor, compressor will shut down and fail-
ure is detected through feedback contacts (size 034 and 038
only).
IMPORTANT: The microprocessor memory and the
display will be cleared if the power to the microproces-
sor is shut off. DO NOT attempt to bypass, short, or
modify the control circuit or electronic boards in any
way to correct a problem. This could result in a haz-
ardous operating condition.
CR Failure — If CR fails with large relay either open or closed,
microprocessor will detect this, lock compressor off, and in-
dicate an error.
Relay Board Failure — If small 24-v relay on the relay board
fails, microprocessor will detect this through feedback con-
tacts and indicate an error.
Processor Board Failure — If hardware that monitors feed-
back switch fails and processor board fails to energize the
relay board relay to ON position, an error may be indicated.
CODES 51, 52, 55, 56: COMPRESSOR FAILURE — If con-
trol relay (CR) opens while compressor should be operating,
compressor will stop and microprocessor will energize alarm
light and display a code of 51 , 52 , 55 or 56 (de-
pending on compressor) when display button is pushed. The
compressor will be locked off; to reset, the ON-OFF switch
must be turned to OFF and then to ON position.
If lead compressor in a refrigerant circuit is shut down,
the other compressor in that circuit will also be shut down
and locked off. Only the error code for the lead compressor
will be displayed.
The control does not detect compressor circuit breaker
failures.
Wiring Problem — A wiring error or a loose wire may cause
the feedback circuit to be broken.
Table 22 — Diagnostic Codes
DISPLAY
DESCRIPTION OF FAILURE
ACTION TAKEN
BY CONTROL
RESET
METHOD
PROBABLE CAUSE
51
55
52
56
Compressor 1 failure
Circuit 1 shut off
Manual
Manual
Manual
Manual
High-pressure switch or high dis-
charge gas thermostat switch
trip, compressor ground current
Ͼ 2.5 amp or compressor board
relay on when it is not supposed
to be on. Wiring error between
electronic control and compres-
sor protection module.
Compressor 2 failure
Compressor 3 failure
Compressor 4 failure
Circuit 2 shut off
Compressor 3 shut off
Compressor 4 shut off
59
60
Loss-of-charge circuit 1
Loss-of-charge circuit 2
Circuit 1 shut off
Circuit 2 shut off
Manual
Manual
This indicates either a low refrig-
erant charge, or a loss-of-charge
switch failure.
63
64
Low oil pressure circuit 1
Low oil pressure circuit 2
Circuit 1 shut off
Circuit 2 shut off
Manual
Manual
Not used; Check jumper on pro-
cessor board.
70
Illegal unit configuration
Unit will not start
Manual
Configuration error (see Note 1).
71
72
75
Supply-air thermistor failure
Unit shut off
Auto.
Auto.
Auto.
Thermistor or resistor failure, wir-
ing error, or thermistor or resistor
not connected to the processor
board.
Return-air thermistor failure
Use default value
Unit shut off
Circuit 1 saturated condensing thermistor
76
Circuit 2 saturated condensing thermistor
Unit shut off
Auto.
81
Reset temperature thermistor failure
Stop reset
Auto.
82
83
84
85
86
87
Leaving-air set point potentiometer failure
Economizer potentiometer failure
Use default value
Close economizer
Stop reset
Stop demand limit
Close economizer
Use default value
Auto.
Auto.
Auto.
Auto.
Auto.
Auto.
Potentiometer improperly con-
nected, potentiometer setting out
of range, potentiometer failure or
wiring error.
Reset limit set point potentiometer failure
Demand limit potentiometer failure
Minimum economizer potentiometer failure
Warm-up set point potentiometer failure
NOTES:
1. Illegal unit configuration caused by missing programmable header or both unloader DIP switches on.
2. All auto. reset failures that cause the unit to stop will restart when the error has been corrected.
3. All manual reset errors must be reset by turning the control switch off and then back on.
4. Valid resistance range for the thermistors is 363,000 to 585 ohms.
5. Codes 53, 54, 57, 58, 61, 62, 65-69, 73, 74, and 77-80 are not used on these units.
45
CODES 59 AND 60: LOW-PRESSURE SWITCH — These
codes are used to indicate a low-pressure switch failure.
CODE 82: LEAVING-AIR TEMPERATURE SET POINT
POTENTIOMETER FAILURE — If leaving-air set point po-
tentiometer (P1 — located on display board) fails, control
will use a default value. A failure will cause an error code of
The processor monitors the low-pressure switch. If the switch
opens, either by low refrigerant charge, circuit failure, or wir-
ing error, the circuit is locked off. Code 59 indicates a failure
of the lead circuit, and as a result, that circuit will be shut
down. Code 60 indicates a failure of the lag circuit, and as
a result, that circuit will be shut down. These codes will only
be displayed when the display button is pressed. To reset the
circuit, the ON-OFF switch must be turned to OFF, then ON
position.
82 to be displayed on display board when display button is
pushed; alarm light will also be energized. A failure is de-
termined by establishing a range of −22 F to 70 F as a valid
range. Anything outside this range will be treated as a fail-
ure. If setting is outside the −22 F to 70 F range, alarm light
will be energized and an error code of 82 will be displayed
when display button is pushed; the control will use a set point
of 70 F. If set point is between −22 F and 45 F, control will
use a set point of 45 F and no error code will be indicated.
If potentiometer returns to normal, control will automati-
cally reset.
NOTE: The full range of the potentiometer is not used for
the cooling set point range of 45 F to 70 F. The full scale
resistance of the potentiometer is 10 Kohms.
CODES 63 AND 64: OIL PRESSURE SWITCH — These
codes are used to indicate an oil pressure switch failure. Since
the units do not have oil pressure switches, these codes are
not used. The terminals on the processor board must be jum-
pered together or an error will occur. If these errors occur,
check jumper between J2-1 and J2-2 for a code 63, or be-
tween J2-3 and J2-4 for a code 64 to be sure jumper is prop-
erly connected. To reset the circuit, the ON-OFF switch must
be turned to OFF and then to ON position.
If a failure occurs, one of the following is a probable cause:
Incorrect Potentiometer Setting — Apotentiometer turned fully
clockwise or counterclockwise is outside the valid range and
will cause a failure.
Faulty Wiring — If wiring is incorrect between potentiom-
eter and processor board or display board, a failure will
result.
CODE 70: ILLEGAL UNIT CONFIGURATION — If the
unit configuration header is not installed and properly con-
figured, and/or if DIP switches are not properly set, unit will
not start, and an error code of 70 will be indicated on display
board when display button is pushed. Check the header and
DIP switch settings.
CODES 71 TO 76: THERMISTOR/RESISTOR FAILURE
— If measured temperature of a thermistor is less than
−60 F (363,000 ohms) or greater than 180 F (585 ohms), the
appropriate sensor error code (Table 22) will be displayed
when the display button is pushed. The unit will be shut down.
Thermistor failures will automatically reset once the error
has been corrected. If a failure occurs, the following are pos-
sible causes:
Potentiometer Failure — If potentiometer is shorted or open,
a failure will result.
CODE 83: ECONOMIZER FEEDBACK POTENTIOM-
ETER FAILURE — If potentiometer on economizer motor
(P2) fails, control will use a default value of 0% and econo-
mizer outdoor-air dampers will close. The failure will en-
83
ergize alarm light and cause an error code of
to be dis-
played when display button is pushed. This potentiometer is
a 5 to 15 Kohm potentiometer. If potentiometer returns to
normal, control will automatically reset. If a failure occurs,
one of the following is the probable cause.
Faulty Wiring — If the wiring between processor board and
potentiometer is wrong, this will cause a failure.
Thermistor or Resistor Failure — A shorted or open ther-
mistor or resistor will cause the failure.
Wiring Failure — If a wiring error exists that causes a shorted
or open circuit, this will cause a failure.
Processor Board Failure — If circuitry on processor board
fails, this could cause an error.
The codes are designated as follows:
Potentiometer Failure — If potentiometer is shorted or open,
this will cause a failure.
Code 71 Supply-Air Thermistor Failure
Code 72 Return-Air Thermistor Failure
Code 73 Not used
Code 74 Not used
Code 75 Circuit 1 Saturated Condensing Thermistor
Code 76 Circuit 2 Saturated Condensing Thermistor
Economizer Damper Stuck — The control has been pro-
grammed to indicate an error if potentiometer travel is less
than 10% of the full range. This would happen if dampers or
damper linkage were hung up and could not move
properly.
CODE 84: RESET LIMIT POTENTIOMETER FAILURE
— This code is applicable only if reset is being used. If reset
is being used, DIP switch 2 must be in the ON position. This
potentiometer (P3) is located on the accessory board. If po-
tentiometer setting is less than 0° F or greater than 80 F,
CODE 81: RESET THERMISTOR OR POTENTIOM-
ETER FAILURE — This is a unique code since the reset
temperature potentiometer (P7) is in series with the space
temperature thermistor (T10). If either one of these compo-
nents fail, reset will be terminated. This error will automati-
cally reset once the situation is corrected. If an error is
detected, the most probable cause is one of the following:
• Thermistor Failure — A shorted or open thermistor will
cause the failure.
• Potentiometer Failure — If the potentiometer is outside of
the valid range (40 to 90 F), a failure will result.
• Wiring Problem — If the circuit is open, a failure will be
detected.
• Processor Board Failure — If the processor board fails (hard-
ware), an alarm will be detected.
84
alarm light will be energized, a diagnostic code of
will
be displayed if display button is pushed, and reset will be
terminated. The full-scale resistance of potentiometer is
10 Kohms, but when installed on the accessory board in par-
allel with the other 2 potentiometers, measured resistance
will be 3.3 Kohms. This failure will automatically reset once
potentiometer returns to normal. If a failure occurs, one of
the following is the probable cause:
DIP Switch Problem — DIP switch 2 is in the ON position
and the accessory board is not installed (accessory board is
standard on these units so it should always be on the unit).
46
potentiometer (P6) is located on the accessory board. If po-
tentiometer is set at less than 0° F or more than 95 F, alarm
Incorrect Potentiometer Setting — Apotentiometer turned fully
clockwise or counterclockwise is outside the valid range and
will result in a failure.
87
light will be energized, a diagnostic code of
will ap-
Faulty Wiring — If the wiring between the potentiometer and
the processor board is incorrect, a failure will result.
Potentiometer Failure — If potentiometer is shorted or open,
a failure will occur.
CODE 85: DEMAND LIMIT POTENTIOMETER (P4) FAIL-
URE — Used only if demand limit is being used. If demand
limit is used, DIP switch 5 must be in the ON position.
Two types of demand limit are available: a field-supplied
and installed single-step control consisting of a 10 Kohm,
3-wire linear potentiometer and an accessory 2-step control
are available from Carrier. The single-step control has a single
potentiometer while 2-step control has 2 potentiometers
(mounted on the demand limit board, see Fig. 26).
pear on the display when display button is pushed, and con-
trol will use a default value of 40 F. If setting is between
0° F and 40 F, control will use a value of 40 F but no di-
agnostic code will be displayed; if setting is between 80 F
and 95 F, control will use a value of 80 F but no diagnostic
code will be displayed.
The potentiometer full-scale resistance is 10 Kohm, but
when wired in parallel with other potentiometers on the ac-
cessory board, measured resistance is 3.3 Kohm.
The failure will automatically reset once potentiometer re-
turns to normal. If a failure occurs, one of the following is
the probable cause:
DIP Switch 4 — If this switch is in the ON position and the
accessory board is not installed (accessory board is standard
on these units, so it should always be on the unit).
Incorrect Potentiometer Setting — If potentiometer is turned
fully clockwise or counterclockwise, potentiometer will be
out of the allowable range, resulting in an error.
Faulty Wiring — If the wiring between the potentiometer and
the processor board is incorrect, an error will occur.
Potentiometer Failure — If potentiometer is shorted or open,
potentiometer will be out of range, resulting in an error.
For both types of demand limit, the control uses only 80%
of the total potentiometer resistance. If resistance of poten-
tiometer is less than 10% or greater than 90%, alarm light
will be energized, a diagnostic code of 85 will be displayed
when the display button is pushed, and demand limit will be
terminated. If a failure occurs, it is probably due to one of
the following:
Potentiometer Failure — If a potentiometer is shorted or open,
a failure will occur.
Incorrect Potentiometer Setting — Apotentiometer turned fully
clockwise or counterclockwise will put potentiometer out of
range resulting in an error.
Faulty Wiring — If wiring between the potentiometer and
the processor board is incorrect, an error will occur.
DIP Switch 5 — If DIP switch 5 is in the ON position and
potentiometer is not installed, an error will occur.
CODE 86: MINIMUM POSITION ECONOMIZER PO-
TENTIOMETER FAILURE — If potentiometer P5 (on ac-
cessory board) setting is less than 0% or greater than 100%,
Thermistor Troubleshooting — The VAV control sys-
tem uses thermistors to measure temperatures of the enter-
ing and supply air, as well as the saturated condensing tem-
peratures of the refrigerant circuits. The resistance versus
temperature and electrical characteristics for all thermistors
in the system are identical. To obtain an accurate reading, a
high-impedance meter (such as a digital meter) must be used.
Thermistors in the VAV control system have a 5 vdc sig-
nal applied across them any time the unit control circuit
is energized. The voltage drop across the thermistor is di-
rectly proportional to the temperature and resistance of the
thermistor.
alarm light will be energized, a code of 86 will be dis-
To determine temperatures at the various thermistor lo-
cations, disconnect the thermistor from the processor board
and measure the resistance across the appropriate thermistor
using a high-quality digital ohmmeter. Use the resistance read-
ing to determine the thermistor temperature.
played when display button is pushed and economizer out-
door air dampers will move to the fully closed position.
The potentiometer full-scale resistance is 10 Kohm, but
when installed in parallel with the other 2 potentiometers on
the accessory board, measured resistance will be 3.3 Kohm.
The microprocessor has been programmed to check the
operation of the thermistors. If the measured temperature is
outside of the range of −24 to 225 F or 98,010 to 282 ohms,
then it will be treated as a sensor failure and a diagnostic
code will be displayed. See Table 17 for sensor temperatures
versus resistance drop. It is also possible to check the op-
eration of the thermistors using the quick test routine.
If a thermistor has failed or the wire is damaged, replace
the complete assembly. Do not attempt to spice the wires or
repair the assembly.
This failure will automatically reset when potentiometer
returns to normal.
If a failure occurs, one of the following is the probable
cause:
DIP Switch 3 — If this switch is in the ON position and the
accessory board is not installed (accessory board is standard
on these units, so it should always be on the unit).
Incorrect Potentiometer Setting — If potentiometer is turned
fully clockwise or counterclockwise, potentiometer will be
out of the allowable range, and an error will result.
Faulty Wiring — If wiring between the potentiometer and
the processor board is incorrect, an error will occur.
Potentiometer Failure — If potentiometer is shorted or open,
potentiometer will be out of range and an error will result.
Electronic Controls Checkout — The following will
help determine whether a processor board, a relay board, dis-
play set point board, accessory board, or 2-step demand limit
module is faulty.
Before checking out any board, do the following:
CODE 87: WARM-UP TEMPERATURE SET POINT FAIL-
URE —Applicable only if morning warm-up is used. Whether
or not unit is equipped with electric resistance heaters, use
of the morning warm-up function is recommended if the unit
is shut down at night or over weekends. In this application,
cooling will remain off and the outdoor-air damper will stay
closed until heat load from the occupied space elevates return-
air temperature to the warm-up set point. If warm-up func-
tion is used, DIP switch 4 must be in the ON position. The
1. At initial start-up, enter the Quick Test mode. This test
will determine if all components are connected and op-
erating properly.
2. If system has been operating and a malfunction occurs,
check display for diagnostic codes. Use diagnostic chart
located on inner panel of access door to control box sec-
tion of unit; this chart will help determine probable cause
of failure.
47
These 2 steps will help determine if a component other
than a board is at fault or if the problem is external to control
circuit.
A volt-ohmmeter will be needed to troubleshoot boards. A
digital meter is preferred but a Simpson 260 or equivalent
will work.
Step 3 — Check Voltage Tolerance Circuitry
1. Turn power to OFF position.
2. Negative test probe on TP18 and system in Quick Test
mode.
3. Check voltage TP18 to TP9.
4. If voltage is greater than ϩ1 vdc, recheck transformer
input voltage.
5. If transformer is okay, replace processor board.
6. Turn power to ON position.
Step 4 — Check Processor Reset Line
1. Turn power to OFF position.
To prevent damage to solid-state electronic components
on boards, meter probes should only be placed on ter-
minals and test points listed in following sections. Do
not short the electrical components, and use extreme care
while working on the processor board.
2. Negative probe on TP18.
3. Check voltage TP18 to TP11.
PROCESSOR BOARD CHECKOUT — Refer to Fig. 48
and 49 for location of terminal pins and test points.
4. If voltage is greater than ϩ3 vdc, reset power and
recheck.
Step 1 — Check Transformer Input to the Board — Connector
J4 is used to connect the control transformer to the processor
board.
1. Set the volt-ohmmeter to ac voltage with a range setting
of approximately 30 v.
5. If voltage is still incorrect, replace processor board.
6. Turn power to ON position.
2. Turn control switch to ON position.
3. Check voltage at following terminals on pin terminal con-
nector J4:
TERMINALS
VOLTAGE (AC)
1 to 2
4 to 6
5 to 6
5 to 4
15.3 to 20.9
16.2 to 22.0
8.1 to 11.0
8.1 to 11.0
4. If voltage is not within range, check primary side.
115-v transformer — 104 to 127 vac
230-v transformer — 207 to 254 vac
5. If primary voltage is not correct, check system fuse, trans-
former, ON-OFF switch, and wiring. If these are okay,
contact power company.
6. If primary voltage is correct, but secondary voltage
(24 v ± 10%) is incorrect, replace transformer.
LEGEND
J
TP
—
—
Pin Terminal Strip
Test Pin
Fig. 48 — Processor Board Test Points
7. Turn control switch to OFF position.
Step 2 — Check Processor Board Power Supply
1. Set meter to approximately 20 vdc.
2. Turn power to OFF position.
J6
J5
R9
C9
R10
C10
R11
R12
C12
R13
C13
C11
3. Connect negative lead to TP18.
4. Turn power switch to ON position and press display but-
ton to enter Quick Test mode.
5. Check voltage between TP18 and each of the following
test pins:
CR9
CR10
CR11
CR12
CR13
TEST PIN
VOLTAGE (DC)
TP3
TP4
ϩ10
ϩ12
ϩ5
C1
C2
C3
C4
C5
C6
C7
C8
TP6
TP10
TP14
TP15
TP7
ϩ5
ϩ12
ϩ12
−5*
CR1
CR2
CR3
CR4
CR5
C19
CR6
CR7
E3
CR8
*If not using a digital meter, leads must be reversed.
6. If voltage is incorrect, replace processor board.
7. Turn power to ON position.
K1
LEGEND
K2
K3
CR
J
K
—
—
—
Control Relay
Pin Terminal Strip
Relay
Fig. 49 — Relay Board Test Points
48
Step 5 — Check Relay Board Outputs from the Processor
Board — This step involves checking the output signals from
relays K1-K3 on the relay board.
5. Place the other lead on terminals shown in table below,
and check voltage at pin terminals on pin terminal con-
nector J10 (see Fig. 51 for pin terminal connector J10
details):
1. Turn power to OFF position.
2. Connect negative test probe to TP19 (meter still set to
dc).
3. Turn switch to ON position and enter Quick Test mode.
4. Connect positive test probe to terminal 14 on pin termi-
nal connector J9, and check voltage from TP19 to ter-
minal 14 on pin terminal connector J9.
PIN TERMINAL
VOLTAGE (DC)
17
18
20*
22*
24
5
5
2.5
2.5
5
*Voltage reading is dependent on the meter’s impedance. Readings
may vary with different meters.
5. If not ϩ12 ± 1 vdc, replace processor board.
6. If voltage is not correct, replace processor board.
Step 7 — Potentiometer Connection Checkout.
1. Turn power to OFF position.
6. Turn switch to OFF position.
7. Remove negative test probe from TP19. Connect positive
test probe to TP15.
8. Turn switch to ON position and go into Quick Test mode.
2. Remove plug connection from pin terminal strip J3.
3. Connect negative meter lead to terminal 2 of J3.
4. Turn switch to ON position and go into Quick Test mode.
9. Place negative lead on terminals shown in Table 23, and
check voltage between TP15 and terminals shown in
Table 23 on pin terminal connector J9. See Fig. 50 for J9
details.
5. Place the other lead on terminals shown in table below,
and check voltage at pin terminals on terminal connector
J3:
PIN TERMINAL
VOLTAGE (DC)
1*
3
2.5
5
6
5
8*
2.5
2.5
5
2.5
2.5
10*
12
13*
14*
*Voltage reading is dependent on the meter’s impedance. Readings
may vary with different meters.
6. If voltage is not correct, replace processor board.
Step 8 − Thermistor Input Connector Checkout
1. Turn power to OFF position.
2. Remove the thermistor connections from pin terminal con-
nector J1, and mark them for later replacement.
Fig. 50 — Relay Board Pin Terminal Connector (J9)
Table 23 — Voltage Reading
3. Connect the negative test lead to test pin TP18.
4. Turn power to ON position, and enter the Quick Test
routine.
J9 PIN NUMBERS
QUICK TEST
STEP NO.
1
2
3
4
5
6
7
8
9
10 11 12 13
1.-2.3.
2.4.
2.5.
2.6.
2.7.
2.8.
2.9.
3.0.
3.1.
3.2.
3.3.
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
12
12
12
12
12
5. Place the other lead on terminals shown in Table 24, and
check the voltages.
6. If voltages are incorrect (per Table 24), replace processor
board.
7. Turn power to OFF position, and replace the thermistor
connections removed in Step 2.
8. Turn power to ON position.
0
0
0
0
0
0
0
0
0
0
12
0
0
0
0
0
0
0
0
0
0
12
12
12
12
12
12
12
12
12
0
0
0
0
0
0
0
12
0
0
0
0
0
0
0
12
0
0
0
0
0
0
0
12 12
12
0
0
0
0
0
0
0
0
0
0
0
0
12
12
12
12
12
12
0
0
0
0
0
0
0
12
0
0
0
0
0
0
0
0
12
0
0
0
0
0
0
12
0
0
NOTES:
1. Pins shown in boldface type will only be energized for 10 sec-
onds. All other pins will be energized continuously while at the proper
quick test step. The control will only stay in the Quick Test routine
for 10 minutes unless the display button is pressed.
2. Acceptable range for the voltage reading:
0 v — 0 to 4 v
12 v — 11 to 13 v
3. If any of these voltages are not measured, replace the processor
board.
Step 6 — Display Board Connection Checkout
1. Turn power to OFF position.
2. Disconnect the ribbon cable.
3. Connect negative lead of meter to TP18.
4. Turn power to ON position and go into Quick Test mode.
Fig. 51 — Display Board Pin Terminal Connector (J10)
49
Table 24 — Pin Terminal Connector J1 Voltages
The following procedure can be used to check out the op-
eration of the relays. To do this, turn the control ON/OFF
switch to the OFF position, and remove the wiring connec-
tors connected to pin terminal connectors J5 and J6. Set the
meter for resistance. If the contacts do not close at the re-
quired quick test step, check the relay outputs from the pro-
cessor board.
Relay Board Checkout (Fig. 5)
Step 1 — Low-voltage relay resistance check.
1. Turn switch to OFF position.
2. Remove plug connection from terminal strip J6.
3. Set meter to measure resistance. Connect negative test
lead to both terminals 11 and 12 of J6.
4. Turn switch to ON position and go into quick test mode.
5. Place other meter lead on terminals shown in Table 26
and check resistances at each quick test step.
PIN
TERMINAL
VOLTAGE
(vdc ± 0.25 v)
1
0
5
0
5
0
5
0
5
0
5
0
5
0
5
0
5
0
5
2
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
6. If these resistances are not correct and relay board out-
puts from processor board have been checked out, re-
place relay board.
Step 2 — High-voltage relay resistance check.
1. Turn switch to OFF position.
2. Remove plug connection from terminal connector J5.
3. Connect negative test lead to terminal 8.
4. Check the resistance between terminals 8 and 5 before
entering Quick Test mode. The resistance should be
infinity.
5. Turn switch to ON position and go into Quick Test mode.
6. Place other meter lead on terminals shown in Table 27
and check resistance at each quick test step.
7. If these resistances are not correct and relay board out-
puts from processor board have been checked per Pro-
cessor Board Checkout section on page 48, replace relay
board.
Step 9 − Thermistor Input Connector Checkout
1. Turn power to OFF position.
2. Disconnect all plugs for pin terminal connector J2 and
mark them for later replacement.
3. Connect a negative test lead to test pin TP18.
4. Turn power to ON position, and enter the Quick Test
routine.
5. Place the other lead on terminals shown in Table 25, and
check the voltages.
6. If voltages are incorrect (per Table 25), replace processor
board.
7. Turn power to OFF position, and replace the plugs re-
moved in Step 2.
8. Turn power to ON position.
Table 25 — Pin Terminal Connector J2 Voltages
DISPLAY BOARD CHECKOUT
Step 1 — Check the Output Voltage from Processor Board
to the Relay Board — Refer to Step 6 — Display Board Con-
nection Checkout section on page 49.
PIN
VOLTAGE
TERMINAL
(vdc ± 0.25 v)
1
0
5
0
5
0
5
0
5
0
5
5
5
5
5
5
5
5
5
5
2
Table 26 — Terminal Strip J6 Connection
Resistance Reading
3
4
7
8
J6 PIN NUMBERS
QUICK TEST
STEP NO.
9
1
ϱ
ϱ
ϱ
ϱ
ϱ
ϱ
0
2
ϱ
ϱ
ϱ
ϱ
ϱ
ϱ
ϱ
0
3
ϱ
ϱ
ϱ
ϱ
ϱ
ϱ
ϱ
ϱ
0
4
ϱ
ϱ
ϱ
ϱ
ϱ
ϱ
ϱ
ϱ
ϱ
ϱ
ϱ
5
ϱ
ϱ
ϱ
ϱ
ϱ
ϱ
ϱ
ϱ
ϱ
0
6
ϱ
ϱ
ϱ
ϱ
ϱ
ϱ
ϱ
ϱ
ϱ
ϱ
0
7
ϱ
0
8
ϱ
ϱ
0
10
13
14
15
17
18
19
20
21
22
23
24
1. to 2.3.
2.4.
2.5.
ϱ
ϱ
ϱ
ϱ
ϱ
ϱ
ϱ
ϱ
ϱ
2.6.
ϱ
ϱ
ϱ
ϱ
ϱ
ϱ
ϱ
ϱ
2.7.
2.8.
2.9.
3.0.
ϱ
ϱ
ϱ
ϱ
3.1.
ϱ
ϱ
ϱ
3.2.
ϱ
ϱ
If Steps 1 through 9 have been competed and the unit still
will not function properly, replace the processor board.
3.3.
ϱ
LEGEND
RELAY BOARD TROUBLESHOOTING — The relay board
contains 13 electromechanical relays. The small relays are
24 vac, and the large relays are 115 vac. These relays are
controlled by the processor through the ribbon cable at-
tached to the relay board.
ϱ
—
Infinity
NOTE: Pins shown in boldface type will be energized for only
10 seconds. All other pins will be energized continuously while at the
proper quick test step. The control will remain in the Quick Test mode
for only 10 minutes unless the display button is pressed.
50
Table 27 — Terminal Strip J5 Connector
Resistance Reading
IMPORTANT: Be careful to avoid damaging the con-
nector or the processor board when taking the voltage
readings.
J5 PIN NUMBERS
QUICK TEST
STEP NO.
1
ϱ
0
0
0
0
2
3
ϱ
ϱ
0
4
5
0
0
0
0
0
Test under the following conditions:
• No power to IN1 or IN2
Terminal 1 to 2 should read 4.5 vdc ±0.1 v
Terminal 2 to 3 should read 5.0 vdc ±0.1 v
• Power to IN2 or to both IN1 and IN2, and P2 set at 24%
Terminal 1 to 2 should read 1.5 vdc ± 0.1 v
1. to 2.5.
2.6
ϱ
0
ϱ
ϱ
ϱ
0
2.7.
ϱ
ϱ
ϱ
2.8.
ϱ
ϱ
2.9. to 3.3.
ϱ
LEGEND
NOTE: Voltage should vary between 0.5 vdc and 2.5 vdc
as the setting of P2 is varied between 0% and 49%.
ϱ
—
Infinity
Terminal 2 to 3 should read 5.0 vdc ± 0.1 v
• Power to IN1 only and P1 set at 50%
Terminal 1 to 2 should read 2.5 vdc ± 0.1 v
Terminal 2 to 3 should read 5.0 vdc ± 0.1 v
NOTE: Voltage should vary between 0.5 vdc and 2.5 vdc
as the setting of P2 is varied between 50% and 100%.
Step 2 — Check the Display LEDs
1. Enter Quick Test mode.
2. If 88 is not displayed, replace display board.
Step 3 — Check Set Point Potentiometer — Advance the dis-
play to quick test step 1.9. to determine if this potentiometer
is set and connected properly.
Step 4 — Check Display Switch — Press switch. If switch
does not click, it is faulty and the display will be energized
continuously. The switch is an integral part of display board
and cannot be replaced separately.
NOTE: If the voltages listed in these 3 tests are not obtained
during testing, the DLCM board must be replaced.
Enthalpy Sensor Checkout — To test operation of
enthalpy sensor, see Table 28.
Table 28 — Enthalpy Sensor Checkout
ACCESSORY BOARD CHECKOUT — The accessory board
can be completely checked using quick test steps 2.0., 2.2.,
and 2.3. It can also be checked out as follows:
TEST
EXPECTED RESULT
AND RESPONSE
Outdoor-air sensor:
1. Remove the accessory board connector from the proces-
sor board and connect an ohmmeter to terminals 3 and 4
on the connector. Numbers are marked on the connector.
See Fig. 15.
2. Set the meter to 10,000 ohms. The resistance value ob-
tained should be 3,333 ohms. Adjust the potentiometers
and the resistance value should not change.
3. Connect the ohmmeter to terminals 3 and 6. As the reset
limit potentiometer is turned clockwise, resistance should
increase from 0 to approximately 3,400 ohms.
4. Connect the ohmmeter to terminals 3 and 5. As the econo-
mizer minimum position potentiometer is turned clock-
wise, resistance should increase from 0 to approximately
3,400 ohms.
Enthalpy sensor + terminal
should be connected to +
Milliammeter reading should be
between 3 and 24 mA if sensor
terminal on motor. Connect the is operating correctly. If reading
positive terminal of a DC
is 0 mA, the sensor is either
milliammeter to the S terminal wired backwards or is defective.
of the sensor and the negative
terminal of the meter to SO
terminal of the enthalpy board.
Indoor-air sensor:
Enthalpy sensor + terminal
should be connected to +
terminal on motor. Connect the is 0 mA, the sensor is either
positive terminal of a DC
milliammeter to the S terminal
of the sensor and the negative
terminal of the meter to SR
terminal of the enthalpy board.
Milliammeter reading should be
between 3 and 24 mA if sensor
is operating correctly. If reading
wired backwards or is defective.
5. Connect the ohmmeter to terminals 3 and 2. As the warm-up
set point potentiometer is turned clockwise, resistance should
increase from 0 to approximately 3,400 ohms.
If any of the Steps 1 through 5 result in any other ohm
reading, replace the board; it cannot be serviced.
TWO-STEP DEMAND LIMIT CONTROL MODULE
(DLCM) TROUBLESHOOTING — If a problem is
suspected in the DLCM board, use the following test
procedure:
The board can only be checked when it is connected to
the processor and the processor is energized so that the DLCM
is supplied with 5 vdc power. The terminals referenced are
shown in Fig. 16. Potentiometers P1 and P2 refer to the DLCM
potentiometers.
51
Economizer Motor — All control of the motor (i.e.,
enthalpy changeover, minimum position control and mixed
air control) is accomplished from the main unit microproces-
sor through a relay board. Service and installation instruc-
tions for the unit should be consulted to verify proper op-
eration of these controls. The economizer motor may be checked
out separately. See Fig. 52 for VAV economizer motor con-
nection information.
Variable Frequency Drive
Factory-installed optional VFD is located near the sup-
ply fan and motor. During any service work or pro-
gramming at the VFD, operation of the fan and motor
is not desirable. Either disable the supply fan or install
an accessory VFD remote display.
Motor Test
NOTE: The VFDs (part no. TOSVERT130-E3) are specially
modified for use on Carrier equipment. Some specifications
and control configuration defaults for Carrier applications
will differ from the VFD manufacturer manual included in
the packet. See Table 29 for listing of Carrier-specific de-
fault values.
Apply 24 volt AC power to terminals T1 and T2 of
motor. Connections to motor terminals 2 and 3 must be
disconnected
A Motor Test
A Expected Result and Response
Jumper 1 to
2 at motor
Motor drives open; if not,
replace motor.
STANDARD TRANSDUCER CONTROL — The VFD moni-
tors and controls duct pressure (DP) via a differential pres-
sure transducer. The pressure transducer is located in the
auxiliary control box (034-048 units) or in the supply fan
compartment (see Fig. 34). The pressure transducer’s low
pressure reference port is connected to the outside of the unit
cabinet by a factory-installed tubing section. The pressure
transducer’s high pressure reference point must be field-
connected to the duct pressure pick-up (field-supplied and
installed in the supply duct).
B Motor Test
B Expected Result and Response
Jumper 1 to
3 at motor
Motor drives closed; if not,
replace motor.
The DP transducer monitors the static pressure in the sup-
ply duct and provides a 4 to 20 mA signal directly to the
VFD. (Refer to Table 13 for transducer output signal (mA)
for actual duct static pressure.) The internal logic of the VFD
compares this signal representing actual duct pressure to the
user-configured DP set point. The VFD automatically ad-
justs its output to the supply fan motor to maintain the de-
sired DP set point. When operating with the factory-standard
DP transducer, the internal PID logic of the VFD is enabled.
LIMIT SWITCHES
CAPACITOR
3
EXTERNAL SIGNAL CONTROL — If the VFD is to be
controlled by an external control system other than the fac-
tory supplied pressure transducer, the internal PID logic func-
tion of the VFD must be disabled. To disable the PID
control:
1. Disconnect all power to the unit and the VFD.
2. Install a jumper across S2-CC (see Fig. 53 and 54 for
VFD terminal board connections).
CW
ECONOMIZER
MOTOR
WINDING
(OPEN)
2
CCW
WINDING
(CLOSE)
T1
T2
1
BRAKE
WINDING
1
3. Remove factory-supplied cable attached to IV and CC.
1
2
3
4. Remove other end of the same cable from the pressure
sensor.
5. Connect field supplied speed reference (4 to 20mA) across
terminals IV-CC.
6. Disable the supply fan motor operation.
7. Reconnect power to the unit and VFD.
CW
FEEDBACK
POTENTIOMETER
8. Reprogram the VFD to accept an external reference (in
the Utility parameters group [Gr.Ut], set parameter item
Fnod [no.312] = 4).
BLU
RED
YEL
9. Enable supply fan motor and return power to the unit.
AUX. SWITCH
SUPPLY FAN MOTOR OVERLOAD PROTECTION — The
VFD provides operating overload protection for the supply
fan motor. The factory has programmed the VFD overload
function to match the factory-installed motor (motor size and
efficiency). If the supply fan motor is changed from the origi-
nal factory selection, the overload value may need to be changed
by the service person. Contact your local Carrier represen-
tative for assistance in determining the proper overload
setting.
LEGEND
Counterclockwise
Clockwise
CCW
CW
—
—
Fig. 52 — Damper Motor Connection Diagram (VAV)
NOTE: Variable frequency drive size is matched to factory-
installed motor size. Do not increase motor size without also
changing to equivalent VFD size.
52
Table 29 — Carrier Default Program Parameter Values
PARAMETER GROUP
PARAMETER
ACC1
DEC1
UL
DEFAULT VALUE
60.0 Sec
60.0 Sec
60.0 Hz
LL
10.0 Hz*
Luln
P3
1
20%
F-P3
P4
0.0 Hz
SEtP
(Setup)
100%
F-P4
tHr1
StC1
StL1
OLN
tYP
60 Hz
See Table 31
0
110%
1
5*
FH
60 Hz
Gr.F
(Fundamental)
Pt
2
FbP1
Fbln
GP
1*
2
.30
Gl
2 sec
GA
0
Gr.Fb
(Feedback)
GFS
P1LL
PuL
80
10
1
PuUl
PuLL
Fsor
Sr.n
10
10
60 Hz
Gr.SF
(Frequency Settings)
1* (054-104 only)
0* (054-104 only)
SrN1
Gr.Pn
(Panel Control)
Fr
0*
1t
1
1t0
0
1t1
56
Gr.St
(Terminal Selection)
1t2
13
1t3
3
1t4
10
UuC
UuCt
ArSt
Cnod
bLSF
Fnod
bLPn
1*
Gr.Pr
2
(Protection)
3
1*
1* (054-104 only)
Gr.Ut
(Utility)
2*
1*
*These settings differ from the Toshiba defaults and are required for Carrier applications.
NOTE: To restore original factory settings, change tYP to 6 in Setup mode (SetP). This restores the VFD original factory settings.
53
If using the VFD display panel, disconnect all power
to the unit and the VFD before entering unit, or use
the accessory remote display module. Disable supply fan
and motor operation before accessing VFD-mounted dis-
play module.
RR
SI S2
S4
RCH
P24
LOW LOW
RES
F
R
S3
P24
ST
RX
FLB
FLA
AM CC CC
PP
IV FP
FM
FLC
When power is first supplied to the VFD, the display au-
tomatically starts with the frequency monitor function of its
standard monitor mode. In the frequency monitor function,
the output frequency is displayed. Push the S/P/M (Setup/
Program/Monitor) key to switch to the Mode Selection menu.
Push the S/P/M key again to toggle the display back to the
standard monitor mode.
4-20mA
Fig. 53 — Variable Frequency Drive Terminal Block
(Size 034-048 Units)
From the Mode Selection menu, the service person can
view all of the monitored status variables, including up to
four user-selected variables and any trip history in the memory.
Refer to the separate VFD Operation Manual for detailed
instructions on accessing diagnostic information, initiating
troubleshooting, and clearing any trip history.
RCH
RES
F
R
S3
P24
LOW LOW
RR
SI S2
S4
P24
ST
RX
FLB
FLA
AM CC CC
PP
IV FP
FM
FLC
Restoring Factory VFD Defaults — The original
factory configuration values are saved in the memory of the
VFD and can be restored by the service person if required.
There are two types of saved file data: Carrier-factory set-
tings (factory programmed settings made to the VFD which
apply specifically to the unit it is installed on) and standard
defaults for general Carrier unit use.
4-20mA
Fig. 54 — Variable Frequency Drive Terminal Block
(Size 054-104 Units)
The Carrier-factory settings are maintained as user set-
tings. These can be restored by entering the Setup mode (in
the S/P/M menu) and setting parameter tYP = 6 on the keypad/
display. This will recall the specific factory defaults for this
unit.
Occasionally it may be necessary to restore the VFD de-
faults to the general Carrier use values. These are stored in
an OPTION ROM (read-only memory chip). However, some
variables may need to be manually changed to match the
specific unit’s factory default settings. To recall the general
Carrier defaults, enter the Setup mode and set parameter
tYP = 3. Refer to Table 30 for items requiring manual
adjustment.
VFD Operation — When troubleshooting the VFD, check
first that all required conditions for VFD operation are
satisfied.
For the VFD to run, the following conditions must be met
at the VFD:
1. Drive enable jumper is installed from terminals CC-ST
(factory supplied) (see Fig. 53 and 54).
2. Proper rotation jumper is installed at terminals R-CC (re-
verse rotation, factory supplied) or terminals F-CC (for-
ward rotation, factory supplied).
Table 30 — Required User Adjusted Defaults
SIZES
All
ITEM
Motor overload settings (see Table 31)
UNIT SIZES
034-048
ROTATION
Reverse
Forward
Forward
JUMPER
R-CC
1. Check jumper CC-F
2. Gr.UT/bLSF = 1
054-074
F-CC
054-104
3. Gr.SF/Sr.n = 1
4. Gr.SF/SrN1 = 0
5. SEtP/tYP = 5 (Save User Settings)
078-104
F-CC
3. Emergency stop jumper is installed from terminals S4-CC
(factory supplied).
4. A 4 to 20 mA signal is applied across terminals IV-C (from
pressure transducer, factory supplied).
5. DIP switch SW1 (located on the VFD’s printed circuit
control panel) must be set to ‘‘I’’ (indicating usage of a
4 to 20 mA input signal at terminals ‘‘IV’’).
6. Speed Control (located on the VFD’s keypad/display) set
for ‘‘Remote’’ (press the ‘‘Speed Ctrl’’ button until LED
‘‘Remote’’ is illuminated).
Table 31 — Motor Overload Settings
UNIT
IFM HP
DESIGNATION
VOLTAGE
tHr1
DESIGNATION
UNIT 48/50
AND
SETTING
Model No.
Position 12
Model No.
Position 15
FK,FY, JK,JY
5
5
6
6
6
6
6
And
And
And
And
And
And
And
N
Q
A
K
Q
Q
T
82.0
86.0
80.0
80.0
80.0
80.0
78.0
7. Programmed according to Carrier defaults.
8. Duct Pressure set point established by user, or use fac-
tory default (30 Hz indicating 2.50-in. wg) (see Table 13).
FKX,FKY,
JKX,JKY
LEGEND
VFD Operational Status — The VFDs contain ex-
tensive self-diagnostic functions which are accessed through
the VFD display panel (located on the front of the VFD or
at a remote location when the accessory remote display pack-
age has been installed).
IFM
—
Indoor Fan Motor
Unit Wiring — A typical wiring schematic is shown in
Fig. 55.
54
LEGEND AND NOTES FOR FIG. 55
ALM
C
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
Alarm
LAT
LPS
MTR
MV
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
Leaving-Air Temperature
Low-Pressure Switch
Motor
Contactor
CB
Circuit Breaker
CCB
COMP
CH
Control Circuit Breaker
Compressor
Main Valve
NC
Normally Closed
Normally Open
Crankcase Heater
Control Relay
NO
CR
OFC
OFM
OMR
PCB
PEC
PEDM
PEM
P, PL
RCB
RES
RFC
RFM
SCT
TB
Outdoor Fan Contactor
Outdoor (Condenser) Fan Motor
Outdoor Motor Relay
Power Exhaust Circuit Breaker
Power Exhaust Contactor
Power Exhaust Damper Motor
Power Exhaust Motor
Plug
DPS
DPT
EAT
EC
Differential Pressure Switch
Discharge Pressure Transducer
Enering-Air Temperature
Enthalpy Control
ECR
EOR
EQUIP
FS
Economizer Close Relay
Economizer Open Relay
Equipment
Fan Status Switch
Ground
Return Fan Circuit Breaker
Resistor
Return Fan Contactror
Return Fan Motor
Saturated Condensing Thermistor
Terminal Block
Transformer
Unloader
Variable Frequence Drive
GND
HIR
Heat Interlock Relay
High-Pressure Switch
Heater Relay
HPS
HR
HTR
IDC
Heater
Induced Draft Contactor
Induced Draft Motor
Indoor (Evaporator) Fan Contactor
Indoor Fan Circuit Breaker
Inlet Guide Vanes
Inlet Guide Vanes Motor
TRAN
U
VFD
IDM
IFC
IFCB
IGV
Field Wiring
Factory Wiring
IGVM
NOTES:
H4
H3
1. Connect TRAN1 to
for 460 v units. Connect to
for 230 v
units. If 208/230 v units are run with a 208 v power supply
H2
connect to
.
2. Connect TRAN2 to BLK lead for 460 v units. Connect to ORN lead
for 230 v units. If 208/230 v units are run with a 208 v power sup-
ply connect to RED lead.
3. Circuit breaker must trip amps are equal to or less than 156% FLA
(full load amps) for CB1 and CB2. All others are 140%.
4. If any of the original wire furnished must be replaced, it must be
replaced with type 90° C wire or its equivalent.
5. Number(s) indicates the line location of contacts. A bracket over
(2) numbers signifies single pole double throw contacts. An un-
derlined number signifies a normally closed contact. Plain num-
bers (no lines), signify a normally opened contact.
6. Condenser fan motors are thermally protected.
7. Three phase motors are protected under primary single phasing
conditions.
55
5 6
5 7
SERVICE TRAINING
Packaged Service Training programs are an excellent way to increase your knowledge of the equip-
ment discussed in this manual, including:
• Unit Familiarization
• Installation Overview
• Maintenance
• Operating Sequence
A large selection of product, theory, and skills programs are available, using popular video-based for-
mats and materials. All include video and/or slides, plus companion book.
Classroom Service Training which includes ‘‘hands-on’’ experience with the products in our labs can
mean increased confidence that really pays dividends in faster troubleshooting and fewer callbacks.
Course descriptions and schedules are in our catalog.
CALL FOR FREE CATALOG 1-800-962-9212
[
] Packaged Service Training
[
] Classroom Service Training
Copyright 1999 Carrier Corporation
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
Book 1 PC 111 Catalog No. 534-716 Printed in U.S.A. Form 48/50F,J-1T Pg 58 4-99 Replaces: 48/50D,F,J-1T
Tab 1a 1b
1
START-UP CHECKLIST
MODEL NO.:
DATE:
SERIAL NO.:
TECHNICIAN:
I. PRE-START-UP:
Ⅺ VERIFY THAT UNIT IS LEVEL
Ⅺ VERIFY THAT ALL PACKING MATERIALS HAVE BEEN REMOVED FROM UNIT
Ⅺ LOOSEN ALL SHIPPING HOLDDOWN BOLTS AND REMOVE SHIPPING BRACKETS PER INSTRUCTIONS
Ⅺ VERIFY THAT COMPRESSOR SUSPENSION SPRINGS HAVE BEEN LOOSENED PER INSTRUCTIONS
Ⅺ VERIFY OPENING OF ECONOMIZER HOODS
Ⅺ VERIFY INSTALLATION OF EXHAUST HOODS
Ⅺ CONFIRM THAT TUBING FOR SPACE AND SUPPLY DUCT PRESSURES HAS BEEN INSTALLED
Ⅺ VERIFY THAT CONDENSATE CONNECTION IS INSTALLED PER INSTRUCTIONS
Ⅺ VERIFY THAT POWER SUPPLY MATCHES UNIT DATA PLATE
Ⅺ VERIFY THAT ALL ELECTRICAL CONNECTIONS AND TERMINALS ARE TIGHT
Ⅺ CHECK GAS PIPING FOR LEAKS (48FK,JK ONLY)
Ⅺ CHECK THAT INDOOR-AIR FILTERS ARE CLEAN AND IN PLACE
Ⅺ CHECK FAN WHEEL AND PROPELLER FOR LOCATION IN HOUSING/ORIFICE, AND VERIFY SET SCREWS
ARE TIGHT
Ⅺ VERIFY THAT FAN SHEAVES ARE ALIGNED AND BELTS ARE PROPERLY TENSIONED
Ⅺ OPEN SUCTION, DISCHARGE, AND LIQUID LINE SERVICE VALVES
Ⅺ CHECK COMPRESSOR OIL LEVEL SIGHT GLASS AND VERIFY PROPER LEVEL
Ⅺ VERIFY THAT CRANKCASE HEATERS HAVE BEEN ENERGIZED FOR 24 HOURS
Ⅺ CHECK VOLTAGE IMBALANCE
LINE-TO-LINE VOLTS:
(AB + AC + BC)/3 = AVERAGE VOLTAGE =
MAXIMUM DEVIATION FROM AVERAGE VOLTAGE =
AB
V
AC
V
BC
V
V
V
VOLTAGE IMBALANCE = 100 X (MAX DEVIATION)/(AVERAGE VOLTAGE) =
%
IF OVER 2% VOLTAGE IMBALANCE, DO NOT ATTEMPT TO START SYSTEM!
CALL LOCAL POWER COMPANY FOR ASSISTANCE.
II. PRELIMINARY CHECKLIST ITEMS:
CONTROL SETTINGS
Ⅺ DIP SWITCHES SET TO MATCH INSTALLED ACCESSORIES:
SUPPLY AIR SET POINT RESET (DIP SWITCH NO. 4 ON)
MORNING WARM-UP (DIP SWITCH NO. 4 ON)
DEMAND LIMIT (DIP SWITCH NO. 5 ON)
Ⅺ SUPPLY AIR SET POINT (P1) SET BETWEEN 45 AND 70 F
Ⅺ ECONOMIZER MINIMUM POSITION (P5) SET PER PLANS
Ⅺ SUPPLY AIR SET POINT RESET SETTINGS:
RESET INITIATION TEMPERATURE (P7) (TYPICALLY 68 TO 72 F)
RESET LIMIT TEMPERATURE (P3) (TYPICALLY 60 TO 70 F)
Ⅺ MORNING WARM-UP TEMPERATURE (TYPICALLY 50 TO 65 F)
Ⅺ IGV/VFD DUCT PRESSURE SET POINT PER PLANS
Ⅺ BUILDING PRESSURE (MODULATING POWER EXHAUST) SET PER PLANS
Ⅺ DEMAND LIMIT SETTINGS PER PLAN:
SINGLE STEP DEMAND LIMIT (P4) SET (TYPICALLY 25 TO 50%)
TWO-STEP DEMAND LIMIT
DLCM-P1 SET (TYPICALLY 50 TO 75%)
DLCM-P2 SET (TYPICALLY 0 TO 25%)
Ⅺ OCCUPIED/UNOCCUPIED SWITCH INSTALLED PER FIG. 21 (CLOSE TO START UNIT)
CL-1
III. START-UP
CHECK EVAPORATOR FAN SPEED AND RECORD.
CHECK CONDENSER FAN SPEED AND RECORD.
AFTER AT LEAST 10 MINUTES RUNNING TIME, RECORD THE FOLLOWING MEASUREMENTS:
COMP A1
COMP A2
COMP B1
COMP B2
OIL PRESSURE
SUCTION PRESSURE
SUCTION LINE TEMP
DISCHARGE PRESSURE
DISCHARGE LINE TEMP
ENTERING CONDENSER AIR TEMP
LEAVING CONDENSER AIR TEMP
EVAP ENTERING AIR DB TEMP
EVAP ENTERING AIR WB TEMP
EVAP LEAVING AIR DB TEMP
EVAP LEAVING AIR WB TEMP
COMPRESSOR AMPS (L1)
COMPRESSOR AMPS (L2)
COMPRESSOR AMPS (L3)
ELECTRICAL
SUPPLY FAN AMPS
ELECTRIC HEAT AMPS L1
EXHAUST FAN AMPS
L2 L3
TEMPERATURES
OUTDOOR-AIR TEMPERATURE
RETURN-AIR TEMPERATURE
COOLING SUPPLY AIR
F
F
F
DB (Dry-Bulb)
DB
F
WB (Wet-Bulb)
PRESSURES
GAS INLET PRESSURE
IN. WG
GAS MANIFOLD PRESSURE STAGE NO. 1
REFRIGERANT SUCTION CIRCUIT NO. 1
REFRIGERANT DISCHARGE CIRCUIT NO. 1
IN. WG
PSIG
STAGE NO. 2
IN. WG
PSIG
CIRCUIT NO. 2
CIRCUIT NO. 2
PSIG
PSIG
Ⅺ VERIFY REFRIGERANT CHARGE USING CHARGING CHARTS IN UNIT INSTALLATION INSTRUCTIONS
GENERAL
Ⅺ ECONOMIZER MINIMUM VENT SETTING TO JOB REQUIREMENTS
IV. NOTES
Copyright 1999 Carrier Corporation
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
Book 1
1
PC 111
Catalog No. 534-716
Printed in U.S.A.
Form 48/50F,J-1T
Pg CL-2
4-99
Replaces: 48/50D,F,J-1T
Tab 1a 1b
|