Carrier 48FK038, 48FK044, 48FK048, 48FK054, 48FK064 Controls Operation And Troubleshooting

...

Download

Controls Operation,

and Troubleshooting

CONTENTS

Page

SAFETY CONSIDERATIONS .....................2

GENERAL ...................................2-13

Rooftop Information ............................2

VAV Control System ...........................2

Processor Board ..............................2

• P1 — SUPPLY-AIR SET POINT

• P2 — ECONOMIZER POSITION

• P3 — RESET LIMIT

• P4 — DEMAND LIMIT

• P5 — ECONOMIZER MINIMUM POSITION

• P6 — WARM-UP SET POINT

• P7 — SASP RESET TEMPERATURE

• PROCESSOR BOARD OUTPUTS

• CONFIGURATION HEADER AND DIP SWITCH

ASSEMBLY

Relay Board

Display Board .................................5

Thermistors ...................................5

• T1 — SUPPLY-AIR TEMPERATURE THERMISTOR

• T2 — RETURN-AIR TEMPERATURE THERMISTOR

• T3 — SATURATED CONDENSING TEMPERATURE,

CIRCUIT 1

• T4 — SATURATED CONDENSING TEMPERATURE,

CIRCUIT 2

• T10 — RESET TEMPERATURE

Compressor Operation

• CONTROL RELAY (CR)

Accessory Board

• P3 — RESET LIMIT

• P5 — ECONOMIZER MINIMUM POSITION

• P6 — MORNING WARM-UP TEMPERATURE

Single-Step Demand Unit

Demand Limit Control Module (DLCM) ............7

Economizer ..................................10

• ENTHALPY CONTROL

• DIFFERENTIAL ENTHALPY

Variable Frequency Drive (VFD)

Temperature Reset ............................12

CONTROLS INSTALLATION ...................13-25

Control Wiring ...............................13

• NIGHT SETBACK THERMOSTAT

• SPACE TEMPERATURE RESET ACCESSORY

(50DJ900021)

Space Temperature Reset

• INSTALLATION

• CONFIGURATION

• OPERATING SEQUENCE

Demand Limit

• SINGLE-STEP DEMAND LIMIT

• TWO-STEP DEMAND LIMIT

• INSTALLATION

• CONFIGURATION

• OPERATING SEQUENCE

Control From Remote Building Management

System (BMS)

• OCCUPIED/UNOCCUPIED

..................................5

.........................7

..............................7

.......................7

.................12

......................13

................................18

..............................19

48FK,JK034-074

50FK,FY,JK,JY034-104

Variable-Air Volume Rooftop Units

• NIGHT SETBACK CONTROL

• UNIT SUPPLY AIR SET POINT ADJUSTMENT

• DEMAND UNIT (1-STAGE OR 2-STAGE)

• SUPPLY DUCT PRESSURE SET POINT ADJUSTMENT

• EXTERNAL ALARM SIGNAL

• REMOTE ECONOMIZER CONTROL

Smoke Control Modes

.........................21

• FIRE SHUTDOWN MODE

• PRESSURIZATION MODE

• EVACUATION MODE

• SMOKE PURGE MODE

• INSTALLATION

• CONFIGURATION

• OPERATING SEQUENCE

Air Pressure Tubing

...........................23

• INLET GUIDE VANES

• VARIABLE FREQUENCY DRIVE

• MODULATING POWER EXHAUST

START-UP

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

(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

•

.................................25-30

• CODES 20 THROUGH 30 AND 88, OPERATIONAL

STATUS

• 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

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

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

•

........................36

Page

Manufacturer reserves the right to discontinue, or change at any time, speciﬁcations or designs without notice and without incurring obligations.

Book 1 1 Tab 1a 1b

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

CONTENTS (cont)

Page

CODES 59 AND 60: LOW-PRESSURE SWITCH

•

• CODES 63 AND 64: OIL PRESSURE SWITCH

• CODE 70: ILLEGAL UNIT CONFIGURATION

• CODES 71 TO 76: THERMISTOR/RESISTOR

FAILURE

• CODE 81: RESET THERMISTOR OR

POTENTIOMETER FAILURE

• CODE 82: LEAVING-AIR TEMPERATURE SET POINT

POTENTIOMETER FAILURE

• CODE 83: ECONOMIZER FEEDBACK

POTENTIOMETER FAILURE

• CODE 84: RESET LIMIT POTENTIOMETER

FAILURE

• CODE 85: DEMAND LIMIT POTENTIOMETER (P4)

FAILURE

• CODE 86: MINIMUM POSITION ECONOMIZER

POTENTIOMETER FAILURE

• CODE 87: WARM-UP TEMPERATURE SET POINT

FAILURE

Thermistor Troubleshooting

Electronic Controls Checkout ..................47

....................47

• PROCESSOR BOARD CHECKOUT

• RELAY BOARD TROUBLESHOOTING

• DISPLAY BOARD CHECKOUT

• ACCESSORY BOARD CHECKOUT

• TWO-STEP DEMAND LIMIT CONTROL MODULE

(DLCM) TROUBLESHOOTING

Enthalpy Sensor Checkout

Economizer Motor ............................52

Variable Frequency Drive ......................52

.....................51

• STANDARD TRANSDUCER CONTROL

• EXTERNAL SIGNAL CONTROL

• SUPPLY FAN MOTOR OVERLOAD PROTECTION

VFD Operation

VFD Operational Status ........................54

Restoring Factory VFD Defaults ................54

Unit Wiring ..................................54

START-UP CHECKLIST ..................CL-1, CL-2

...............................54

SAFETY CONSIDERATIONS

Installing, starting up, and servicing this equipment can be hazardous due to system pressures, electrical components; and equipment location (roof, elevated structures, etc.). Only trained, qualiﬁed installers and service mechanics should install, start up, and service this equipment.

When working on this equipment, observe precautions in the literature; on tags, stickers, and labels attached to the equipment, and any other safety precautions that apply. Follow all safety codes. Wear safety glasses and work gloves. Use care in handling, rigging, and setting this equipment, and in handling all electrical components.

Electrical shock can cause personal injury and death. Shut off all power to this equipment during installation and service. There may be more than one disconnect switch. Tag all disconnect locations to alert others not to restore power until work is completed.

GENERAL

IMPORTANT: This literature contains controls, operation, and troubleshooting data for 48FK,JK and 50FK,FY,JK,JY variable air volume rooftop units. Use this guide in conjunction with the separate Installation Instructions literature packaged with the unit.

Carrier 48FK,JK and 50FK,FY,JK,JY units provide ventilation, cooling, and heating (when equipped) in Variable Air Volume (VAV) applications. These units contain factoryinstalled controls which provide full system management. The unit controls also perform self diagnostic tests at unit start-up, monitor operation of the unit, and provide alarms. Information on system operation and status are sent to the central processors by various sensors that are located at the unit and in the conditioned space. Each unit is equipped with a display board.

Rooftop Information — The rooftop controls cycle

supply-fan motor, compressors, and unloaders to maintain the proper temperature conditions. The controls also cycle condenser fans to maintain suitable head pressure. Safeties are continuously monitored to prevent the unit from operating under abnormal conditions. The controls provide control of economizer and cycle or control heating as required.

The controls also allow the service person to operate a ‘quick test’so that all the controlled components can be checked for proper operation.

IMPORTANT:The ﬁeld-supplied and installed switch (or timeclock) MUST BE CLOSED to put unit into the Occupied mode. Unit WILLNOT START until this is accomplished. See base unit installation instructions literature for details.

VAV Control System — The 30 to 100-ton VAV roof-

top units contain a microprocessor-based electronic control system that controls and monitors the rooftop unit functions.

TheVAV control system is composed of several components:

• processor board

• relay board

• display board

• thermistors

• compressor operation feedback (control relay)

• accessory board

• temperature reset package*

• single-step demand limit*

• two-step demand limit control module* *Field-installed accessories.

The VAV control system monitors and controls the following functions of the rooftop unit:

• supply-air temperature (unit capacity)

• morning warm-up or electric heat (if equipped)

• head pressure control, fan cycling

• economizer position

• diagnostic display

• unit check-out (quick test)

• supply air temperature reset (if equipped)

• demand limiting (if equipped)

This unit uses a microprocessor-based electronic control system. Do not use jumpers or other tools to short out components, or to bypass or otherwise depart from recommended procedures. Any short-to-ground of the control board or accompanying wiring may destroy the electronic modules or electrical components.

Processor Board — The processor board, shown in

Fig. 1, contains the logic and the necessary hardware to drive the outputs and the display board. The processor board is enclosed by a sheet metal cover and a heater. The heater is controlled by a thermostat to keep the processor temperature above 32 F (0° C). All electrical connections are made to the processor board through wire and ribbon cables.

LEGEND

DIP — Dual In-Line Package EPROM — Erasable, Programmable Read-Only Memory EXV — Electronic Expansion Valve

Do not remove label covering EPROM. Removal causes program to be erased.

Fig. 1 — Processor Board

*EPROM HT204485-1-XX where ‘‘XX’’ is the current revision

number.

NOTE: Processor Board is positioned in unit with J3 and J10 connections at the bottom.

Several temperature inputs are connected to the processor. 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.

Several status switches are also monitored. These switches are connected to the processor at pin terminal connector J2. See Fig. 3 and Table 2.

Table 1 — Pin Terminal Connector J1

Thermistor Inputs

CONNECTOR J1

TERMINAL NO.

1,2 Reset Temperature* T10

14,15

16,17 18,19 Return-Air Temperature T2

20,21 Supply-Air Temperature T1

LEGEND

T—Thermistor

*If equipped with accessory temperature reset package.

NOTE: Terminal numbers 3-13 are not used on these units.

TEMPERATURE

INPUT

Saturated Condensing

Temp., Circuit 2

Saturated Condensing

Temp., Circuit 1

UNIT SIZE

034-104

T4 T3

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.

All of the potentiometers must be set before the unit is started in order for the unit to function properly. See StartUp, 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 potentiometer, which may not be the same as the valid range.

LEGEND

T—Thermistor

Field Wiring Accessory

Fig. 2 — Pin Terminal Connector J1

Thermistor Inputs

LEGEND

CR — Control Relay EC — Enthalpy Control LPS — Low-Pressure Switch

Fig. 3 — Pin Terminal Connector J2

Status Switch Inputs

Table 2 — Pin Terminal Connector J2

Status Switch Inputs

CONNECTOR J2

TERMINAL NO.

1,2

3,4

7,8

9,10

13,14

15,20

15,24

LEGEND

CR — Control Relay EC — Enthalpy Control LPS — Low-Pressure Switch

NOTE: Terminal numbers 5, 6, 11,12, 16-19, and 21-23 are not used

on these units.

STATUS SWITCH

Oil Pressure,

Circuit 2

Oil Pressure,

Circuit 1

Loss Of Charge,

Circuit 2

Loss of Charge,

Circuit 1

Economizer

Changeover

Compressor Fault

Signal

Compressor Fault

Signal

UNIT SIZE

034-104

Jumpered

LPS2 LPS1

EC CR2 CR1

LEGEND

IN — Input P—Potentiometer Field Wiring RNT — Return Accessory SW — Switch

Factory Wiring

Fig. 4 — Pin Terminal Connector J3

Potentiometer Inputs

The potentiometer locations and functions are as follows:

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 control of economizer position and/or cycling unloaders and compressors.

P2 — ECONOMIZER POSITION — Economizer feedback potentiometer is located on the economizer motor.The microprocessor is programmed to indicate an alarm if the travel during initialization is less than 10% of the total potentiometer’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 processor will try to drive the economizer dampers closed.

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 potentiometer 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.

P4 — DEMAND LIMIT — This potentiometer is located near TRAN4 in the unit control box. The demand limit potentiometer 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 potentiometer and switch must be used.

P5 — ECONOMIZER MINIMUM POSITION — This potentiometer is on the accessory board (provided standard from the factory) located in the unit main control box. This potentiometer 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 economizer 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, Morning 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.

P7 — SASP (SUPPLY AIR SET POINT) RESET TEMPERATURE — This 10 Kohm potentiometer is used only if the accessory, ﬁeld-installed temperature reset package is installed.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 enable SASP reset.

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.

CONFIGURATION HEADERAND DIP SWITCHASSEMBLY — The processor board is programmed to control a variety 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.

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 ﬁeldinstalled options, as well as for several other options that may be unique to the unit. The DIP switches are located under 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.

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.

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 operational error codes.

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 characteristics, 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 number of capacity steps required to maintain a desired supplyair temperature.

T2 — RETURN-AIR TEMPERATURE THERMISTOR — This thermistor is located in the mixed-air portion of the unit cabinet. The thermistor’sprimary function is to provide morning warm-up information. This sensor will also provide differential information for the processor during cooling operation (such as the rate of change for a capacity step).

T3 — SATURATEDCONDENSINGTEMPERATURE, CIRCUIT 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 — SATURATEDCONDENSINGTEMPERATURE, CIRCUIT 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.

T10 — RESET TEMPERATURE — This thermistor is used only if the accessory temperature reset package is used. It provides occupied space temperature information to the processor, which determines whether or not reset is required. The thermistor is remotely mounted outside the unit in the conditioned space.

Table 3 — Output Pin and Terminal Assignments

OUTPUT PIN-

TERMINAL

J6-1

J6-2

J6-3

J6-4

J6-5

J6-6 J6-7 Economizer Open Relay (K7) EOR

J6-8 Economizer Close Relay (K8) ECR J5-1 Supply Fan Relay (K9) J5-2 Morning Warm-Up Relay (K10) HIR

J5-3

J5-4 J5-5 External Alarm Relay (K13) ALM

LEGEND

ALM — Alarm CR — Control Relay ECR — Economizer Close Relay EOR — Economizer Open Relay HIR — Heat Interlock Relay IFC — Indoor (Evaporator) Fan Contactor OFC — Outdoor (Condenser) Fan Contactor U—Unloader

Stage 1 Compressor Relay (K1)*

Stage 2 Compressor Relay (K2)*

Stage 3 Compressor Relay (K3)*

Stage 4 Compressor Relay (K4)†

Stage 5 Compressor Relay (K5)†

Stage 6 Compressor Relay (K6)†

Stage 1 Condenser Fan Relay (K11)

Stage 2 Condenser Fan Relay (K12)

NAME RATING DEVICE

CR1 U2**

24 vac

115 vac

*Circuit 1.

†Circuit 2.

**U2 is not used on 044 units.

††OFC2 on 034-048 units; OFC3 on 054-104 units.

\ Used on 054-104 units only.

Not Used

CR2

Not Used

IFC

OFC2/OFC3 ††

OFC4 \

LEGEND

CR — Control Relay J—Terminal Pin Connectors K—Relay

Fig. 5 — Relay Board

P1 SUPPLY AIR SET POINT POTENTIOMETER

TWO-DIGIT DISPLAY

DISPLAY BUTTON

Fig. 6 — Display/Set Point Board

Compressor Operation

CONTROL RELAY (CR) — This relay provides information to the processor about compressor operation (one control relay per compressor). The relay controls and protects the compressor and also controls the crankcase heater.

A control signal to check the safety statuses and to start the compressor is sent from the relay board. This signal travels through all of the safeties: the high-pressure switch, and the internal protector (where used) and on to the control relay 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 safeties, energizes the compressor contactor coil, and deenergizes the crankcase heaters. A fault will be detected by the processor if the control relay opens during operation or startup. 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.

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.

P5 — ECONOMIZER MINIMUM POSITION — This potentiometer controls the set point for the minimum position of the economizer.

P6 — MORNING WARM-UP TEMPERATURE—This potentiometer 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 V AV 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 differsdepending on the number of capacity steps.

A3-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 demand 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.

Demand Limit Control Module (DLCM) — The

DLCM provides a 2-step demand limit control using an external switch. The ﬁrst step is between 50% and 100% of the maximum compressor displacement. See Fig. 16. The second step is between 0% and 49% of the maximum compressor displacement. The exact percentage differs depending on the number of capacity steps.

Two adjustable potentiometers are used to set the 2 demand limit points. Potentiometer P1 is used to set a demand limit between 50% and 100% of the unit capacity. Potentiometer 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 module, all capacity stages can be used. When power is supplied to terminal IN1 only, the ﬁrst step of the demand limit control 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.

GAS SECTION HORIZONTAL SUPPLY SECTION

(48FK,JK ONLY) (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

GAS SECTION HORIZONTAL DISCHARGE SECTION (50FY,JY)

(48FK,JK) 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

Fig. 10 — Thermistor T1 Location, 50FK,JK054-074 Units

FAN DISCHARGE/ELECTRIC HEAT SECTION

STANDARD

FILTERS

BAG

FILTERS

Fig. 11— Thermistor T2 Location, Size 034-048 Units

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 userconﬁgured 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 differentialenthalpy sensor to enhance economizer control. Refer to the installation section for ﬁeld wiring of the sensor.

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. Enthalpy is sensed by a controller located behind the end outside air hood. The control can be accessed by removing the upper hood ﬁlter. See Fig. 17.

DIFFERENTIALENTHALPY— Added efficienciesin economizer control can be gained by installing a differential enthalpy 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 provide for lower compressor operating costs during integrated economizer cycle operation. The differential enthalpy sensor is installed in the return-air duct.

054 UNITS

064, 074, 078 UNITS

Fig. 14 — Thermistor T3 and T4 Locations, Size 054-104 Units

088, 104 UNITS

LEGEND

ECON — Economizer MIN — Minimum P—Potentiometer VAV — Variable-Air Volume

Fig. 15 — Accessory Relay Board

(Standard; Factory Supplied)

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 accessed 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 senda4to20mAsignal 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 Sequence 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 supplyair 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 supplyair temperature and the unit controls respond by reducing

LEGEND

IC — Integrated Circuit IN — Input P—Potentiometer RTN — Return

Fig. 16 — Two-Step Demand Limit Module

Fig. 17 — Enthalpy Sensor Location

Fig. 18 — Variable Frequency Drive,

Sizes 034-048 and 078-104

Fig. 19 — Variable Frequency Drive, Sizes 054-074

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 userconﬁgured set points for supply duct pressure. Allowing the supply-air temperature to be reset to a higher value maintains air circulation in the space without costly overcooling.

The accessory package is required for temperature reset.

The accessory includes:

• thermistor T10, to monitor space temperature

• reset temperature potentiometer P7, to establish start temperature 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 wiring 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

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.)

CONTROLS INSTALLATION

The VAV units may be used in applications with additional control features, options, or accessories. Refer to the appropriate accessory installation instructions for more information on installing that accessory.Unit control box component 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

• Motormastert I control

• space temperature reset

• night setback thermostat (ﬁeld-supplied)

• single step demand limit

• two-step demand limit

• 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 between 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 require 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 (depending 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.

There are no required 115-volt ﬁeld wiring connections, therefore no provisions have been made in the unit for running 115-volt wiring. If any of the ﬁeld-installed options requiring 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 timeclock occupied/unoccupied switch and is used to operate unit during unoccupied times at more economical temperatures. (See Fig. 23.)

SPACE TEMPERATURE RESET ACCESSORY (50DJ900021) — Consists of a thermistor (T10) and a reset board with a potentiometer (P7) that is used to set space temperature at which reset starts. Mount reset board in unit control box or other convenient place. Wire thermistor in series 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).

Space Temperature Reset

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.

Locate the thermistor T10 in a suitable location in the occupied space per instructions.

Wire T10 to the reset board and to the unit control terminal 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 temperature, 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 package) switch 2 to position ON. (Disconnect control power before changing DIP switch positions; reconnect power after all changes have been made.)

CONFIGURATION — Set points for reset operation are established at potentiometers P7 and P3 (on the reset board).

Potentiometer P7 — Reset temperature set point (temperature 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 calculated using the following formula:

= 13,084 – T10

Where: P7

= the desired set point of the P7 potentiometer in ohms

T10R= the resistance of the T10 thermistor for the desired

set point

Fig. 20 — Unit Control Box Arrangement, Sizes 034-048

Fig. 21 — Unit Control Box Arrangement, Sizes 054-078

Fig. 22 — Unit Control Box Arrangement, Sizes 088 and 104

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: MSP = Modiﬁed Leaving-Air Set Point

OCCUPIED/UNOCCUPIED

SWITCH

SP = Supply-Air Set Point P3 = Maximum Supply-Air Temperature (reset limit) P7 = Reset Initiation Temperature (reset set point)

NIGHT SETBACK THERMOSTAT

T10 = Actual Space Temperature 3 = Ratio for reset (F) (ﬁxed parameter)

Table 4 — Thermistor Resistance and

NOTES:

1. Occ/Unocc switch closes when occupied.

2. Night setback thermostat closes when in night setback heating.

Fig. 23 — Occupied/Unoccupied Switch with

Night Setback Thermostat

034-048: TB3 054-104: TB4

N.O.

N.C.

FIELD SUPPLIED POWER SOURCE

SIGNAL TO ROOM TERMINALS

Fig. 24 — Heat Interlock Relay

034-048: TB3 054-104: TB4

T10

RESET BOARD

Fig. 25 — Accessory Reset Board

EXAMPLE: T10 desired set point is 70 F.

from Table 4 for 70 F is 5929 ohms.

T10

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

Voltage Drop Characteristics

TEMP

(F)

31.0 16813.8 3.582

32.0 16345.7 3.553

33.0 15892.2 3.523

34.0 15452.7 3.494

35.0 15026.7 3.464

36.0 14613.9 3.434

37.0 14213.6 3.404

38.0 13825.5 3.373

39.0 13449.2 3.343

40.0 13084.2 3.312

41.0 12730.1 3.281

42.0 12386.6 3.250

43.0 12053.3 3.219

44.0 11730.0 3.187

45.0 11416.1 3.156

46.0 11111.5 3.124

47.0 10815.8 3.093

48.0 10528.7 3.061

49.0 10250.0 3.029

50.0 9979.3 2.997

51.0 9716.5 2.965

52.0 9461.3 2.933

53.0 9213.4 2.901

54.0 8972.6 2.869

55.0 8738.6 2.837

56.0 8511.4 2.805

57.0 8290.6 2.772

58.0 8076.1 2.740

59.0 7867.7 2.708

60.0 7665.1 2.676

61.0 7468.3 2.644

62.0 7277.1 2.612

63.0 7091.2 2.581

64.0 6910.6 2.549

65.0 6735.1 2.517

66.0 6564.4 2.486

67.0 6398.6 2.454

68.0 6237.5 2.423

69.0 6080.8 2.391

70.0 5928.6 2.360

71.0 5780.6 2.329

72.0 5636.8 2.299

73.0 5497.0 2.268

74.0 5361.2 2.237

75.0 5229.1 2.207

76.0 5100.8 2.177

77.0 4976.0 2.147

78.0 4854.8 2.117

79.0 4736.9 2.088

80.0 4622.4 2.058

reset set point (T10 > P7), no reset will occur.

If space temperature is equal to or less that reset set point

(T10 < P7), the LED will display and reset will begin.

RESISTANCE

(Ohms)

VOLTAGE

DROP (v)

SIZES 034-048 TB3

TO ACCESSORY SPACE TEMPERATURE RESET CONTROL BOARD

SIZES 054-104 TB4

SIZES 034-048 TB3

12 15

TO ACCESSORY SPACE

TEMPERATURE RESET

CONTROL BOARD

SIZES 054-104 TB4

12 15

RED BLK

RED

BLK

SENSOR 1 SENSOR 2 SENSOR 3 SENSOR 4

RED BLK

SPACE TEMPERATURE RESET — 4 SENSOR AVERAGING APPLICATION

RED BLK

BLK

SENSOR 1

RED

RED BLK

SENSOR 2

RED BLK

SENSOR 3

RED

BLK

SENSOR 4

NOTE:Sensorpart number is HH79NZ014.

BLK

RED

SPACE TEMPERATURE RESET — 9 SENSOR AVERAGING APPLICATION

Fig. 26 — Space Temperature Sensor Averaging

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 available compressor staging capacity according to user set points established at demand limit potentiometer(s).

The unit controls support two types of demand limit: single-

step and 2-step control. SINGLE-STEPDEMAND 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 resistance 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 required for this function. See installation section for speciﬁcation on potentiometer and ﬁeld wiring.

TWO-STEP DEMAND LIMIT — Two-step demand limit is provided with the installation of the accessory Demand Limit

SENSOR 6SENSOR 5

RED BLK

SENSOR 8SENSOR 7 SENSOR 9

RED BLK

Control Module kit plus installation of 2 ﬁeld-supplied control switches (SPST-NO each). This accessory control provides for a ﬁrst step reduction of 50% to 100% of the maximum compressor staging; the second step provides for reduction between 0% and 49%. The exact percentage of capacity reduction differs depending on the number of capacity steps.

When demand limit is active, the LED display will show

code . INSTALLATION

Single-Step Demand Limit — A 3-wire 5 to 20 K-ohm potentiometer must be ﬁeld-supplied and installed. A singlepole 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).

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.

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.)

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 instructions 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.

Connect the ﬁeld input control power wires (from the external 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 desired 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.

Two-Step Demand Limit — Potentiometer P1 and P2 (located on the accessory demand limit control module) establish 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 exact percentage of capacity reduction differsdepending on the number of capacity steps.

OPERATING SEQUENCE 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.

When demand limit is in effect, the LED display will show

code . 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.

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 demand 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 energized 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 . If a potentiometer setting or input is out of range,

22 the control will terminate the demand limit function and show code at the display LED.

034-048: TB3 054-104: TB4

SWITCH

5-20K POTENTIOMETER (P4)

Fig. 27 — Single-Step Demand Limit

Fig. 28 — Two-Step Demand Limit Module

NOTES:

1. Demand limit switches are ﬁeld supplied and wired.

2. Demand limit control module terminal blocks will accept up to 12-gage wire.

is ﬁeld wiring.

Fig. 29 — 115-Volt Field Wiring to Accessory

2-Step Demand Limit Control Module

ControlFrom RemoteBuilding ManagementSystem (BMS) —

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.

The unit control system is not a commu-

OCCUPIED/UNOCCUPIED — The unit control system will initiate normal occupied mode functions (including Morning 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 isolated contact set, normally open, and suitable for 24-volts AC pilot duty.

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 (Cooling mode). Both modes are possible by closing the same contacts 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 temperature sensing system and its logic to determine when to initiate unit operation.

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.

The contact closure from the BMS must be an isolated contact set, normally open, suitable for 24-voltsAC 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 DELIVERYduring unoccupied cooling operation. This is most conveniently 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 assuring adequate airﬂow through the rooftop unit during night setback cooling operation. During night setback cooling operation, the return-air temperature (RAT) will be well above normal levels. The higher RAT means that the air temperature leaving the evaporator coil will also be well above normal 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 working in-step with the refrigeration system demand, it is possible to produce low suction pressures and local frosting on the evaporator coil during the night setback cooling operation.

UNIT SUPPLY AIR SET POINT ADJUSTMENT — The minimum Supply Air Set Point (SASP) temperature is established by the setting at Potentiometer P1 on the unit display 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 resistance transducer witha4to20mAor2to10vdcsignal generated by the BMS.

This emulation requires the following ﬁeld-supplied parts:

• 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

Field Connections (see Fig. 30) — Connect ﬁxed resistance with manual potentiometer and variable resistance transducer in series.

Connect wiring to rooftop unit at:

Size 034-044: TB3-12 and TB3-15

Size 054-104: TB4-12 and TB4-15

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 SASPvalue (typically 65 to 70 F). The maximum P3 SASP control limit is 70 F.

Operation —Unit will initiate SASP Reset (adjust conﬁgured SASP upward) when the sum of the resistance (ﬁxed resistance+potentiometer + transducer) exceeds 13.1k-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 +

(P3 − SASP) (0.6 F)

[]

MSP: Modiﬁed SASP (SASP plus Reset) TR: Resistance at transducer R@13.1: 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.

SW with contact closure controlled by the BMS. Set potentiometer P4 manually at the unit control box. Alternatively, potentiometer P4 might also be emulated by a variable resistance transducer, with the BMS now able to adjust the amount of demand limit.

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).

mand Limit section on page 18. 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

Direct 4 to 20 mA Signal — During normal unit operation, the factory-installed VFD receivesa4to20mAsignal from the Duct Pressure (DP) transducer which indicates current supply duct pressure. The VFD then determines the appropriate fan speed (using its internal PID logic feature) and adjusts its output to the supply fan motor to suit. It is possible to emulate this 4 to 20 mA control signal by the BMS, which will transfer control of the VFD to the BMS.

NOTE: When providing a direct 4 to 20 mA signal to the VFD from a BMS with DP logic, disable the PID (proportion integrated derivative calculation process) feature of the VFD.

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 systems. 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).

(3) (100 ohm)

For Single-Step Demand Limit, emulate function of switch

For 2-Step Demand Limit, install the accessory Demand

Follow unit control conﬁguration instructions in the De-

x x (TR − R@13.1)

EXTERNAL ALARM SIGNAL — The unit controls provide an external alarm status signal via a 115-vac output signal at the relay board J5, available at TB2-4 and TB2-5 (common). This signal can be forwarded to the BMS by adding 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).

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 algorithms and diagnostic routines. Consequently, control modiﬁcations that interfere with this standard operating sequence are not recommended.

Economizer position is determined by the unit processor board based on current outdoor air enthalpy status and cooling capacity demand. The economizer damper actuator is a ﬂoating point device with an internal brake and spring return. 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.

Whenever the economizer position potentiometer signal is not consistent with the processor board’s commanded position, 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.

Any attempt to effect an external control of the economizer actuator will lead to an alarm condition and an automatic response by the unit control to attempt to close the dampers.

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.

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 sequences. See Table 5.

FIRE SHUTDOWN MODE — Fire Shutdown mode terminates 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.

PRESSURIZATION MODE — Pressurization mode is intended to keep smoke out of a zone. Factory-installed optional economizer is required for this function. Pressurization is accomplished by:

• opening the economizer (option)

• 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 adjacent zones and prevents or slows entry of smoke into this space from adjacent zones.

034-048: TB3 054-104: TB4

LEGEND

P—Manual Potentiometer R—Fixed Resistor

Field Wiring

TRANSDUCER

BMS

CONTROL

(4 TO 20 MA

2 TO 10 VDC

SIGNAL)

Fig. 30 — Remote SASP Wiring

TB2

LIGHT

RELAY

SIGNAL TO BMS

LEGEND

R—Resistor (Factory Installed)

Factory Wiring Field Wiring

TB2

Fig. 31 — External Alarm Indication

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 function. Evacuation is accomplished by:

• turning supply fan off

• opening the economizer (option required for this function)

• running the exhaust fans (must be provided via option or accessory)

• opening the exhaust dampers

SMOKE PURGE MODE — Smoke Purge mode removes smoke from the interior spaces and replaces it with fresh outside air. Factory-option economizer with optional or accessory 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

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.

Table 5 — Smoke Control Modes

FUNCTION

Supply Fan Off On Off On IGV/VFD† — Open/On — Open/On Economizer Closed Open Open Open Return Air

Damper Exhaust

Fans Exhaust

Damper

LEGEND

IGV — Inlet Guide Vane VAV — Variable Air Volume VFD — Variable Frequency Drive

*Power exhaust option/accessory required for this mode.

†Applicable to VAV units with appropriate options.

Fire

Shutdown

Open Closed Closed Closed

Off Off On On

Closed Closed Open Open

Pressur-

ization

MODE

Evacuation*

Smoke

Purge*

CONFIGURATION — No set points required for Smoke Control modes. Modes are activated by energizing all switches appropriate for each Smoke Control mode.

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.

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.

Evacuation — Atcommand from the ﬁeld switches for Evacuation 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.

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.)

4. Exhaust fans will run at maximum capacity.

5. Exhaust dampers will open.

Table 6 — Smoke Control Switches Required for Each Mode

FIRE

SHUTDOWN

SW-1 SW-1 SW-1 SW-1 SW-2 SW-2 SW-2 SW-2

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. Toinitiate 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.

PRESSURIZATION

SW-4 SW-3 SW-3 SW-5 SW-5 SW-4 SW-6 SW-6 SW-9A/B

SW-9A/B SW-7

EVACUATION

(Modulating Power

Exhaust)

SW-8

SMOKE PURGE

Table 7 — Switch Functions

SWITCH

NUMBER

SW-1 N.C. 115 Deenergize 115-v (OFC, Comp, IFC, Electric Heaters) SW-2 N.C. 115 Deenergize TRAN7 (Process Board) SW-3 N.O. 24 Energize EOR (Open Economizer Outside Air Dampers) SW-4 N.O. 115 Energize IFC and CR-3 (IGV/VFD) SW-5 N.C. 115 Isolate IFC and PEC for Separate Operation SW-6 N.O. 115 Energize PEC (Power Exhaust) SW-7 N.O. 24 Open PED at DPS SW-8 N.C. 24 Block Auto-Close at DPS (Due to Low BP)

SW-9A/B

LEGEND

BP — Building Pressure DPS — Differential Pressure Switch EOR — Economizer Open Relay HIR — Heat Interlock Relay IFC — Indoor Fan Contactor IGV — Inlet Guide Vane N.C. — Normally Closed N.O. — Normally Open PEC — Power Exhaust Contactor PED — Power Exhaust Damper OFC — Outdoor Fan Contactor VFD — Variable Frequency Drive

Air Pressure Tubing — Before options such as inlet

guide vanes (IGV), variable frequency drive (VFD), and/or modulating power exhaust can operate properly, the pneumatic tubing for pressure sensing must be installed. Use ﬁreretardent 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.

Table8—Tubing Size

OPTION UNITS

Inlet Guide Vanes (IGV) ALL

Variable Frequency

Drive (VFD)

Modulating Power Exhaust FK,FKX,JK,JKX

CONFIGURATION VOLTAGE FUNCTION

A: N.O. B: N.C.

115 max Signal Room Terminals to Open (HIR1)

The inlet guide vanes are controlled by a differential pressure 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 tubing.

VARIABLE FREQUENCY DRIVE — The tubing for the duct pressure (DP) control option should sample supply duct pressure about

⁄3of the way out from the unit in the main trunk duct, at a location where a constant duct pressure is desired.

ALL

NOMINAL TUBE

SIZE (in.)

⁄

The duct pressure is sensed by a pressure transducer. The pressure transducer output is directed to the VFD. On 034048 units the DP transducer is located in the auxiliary control box. On 054-104 units, the DP transducer is located in the supply fan section. See Fig. 34. Use a nominal plastic tubing.

⁄8-in. plastic

⁄4-in.

INLET GUIDE VANES — The tubing for the duct pressure (DP) control option should sample supply duct pressure about

⁄3of the way out from the unit in the main trunk duct, at a

location where a constant duct pressure is desired.

034-048 UNITS

TB2TB2 SW-1

054-104 UNITS

TB2TB2 SW-1

TB3

TB2

TB2 SW-6

TB3

SW-3 TB3

SW-4

SW-9A

REMOVE JUMPER

TB2

REMOVE JUMPER

TB2

TB3

REMOVE JUMPER

TB2TB2 SW-2

TB2TB2 SW-5

TB4

TB2

TB2 SW-6

TB4

SW-3 TB4

SW-4

SW-9A

REMOVE JUMPER

TB2TB2 SW-2

TB2

TB2TB2 SW-5

TB2

TB4

TB3

HIR

REMOVED FROM TB3-7

LEGEND

DPS — Differential Pressure Switch HIR — Heat Interlock Relay SW — Switch TB — Terminal Block

SW-9B

WHT

REMOVED FROM C-DPS

DPS

TB4

TB3

SW-7

SW-8

ALL UNITS

GRA

Fig. 32 — Smoke Control Wiring

HIR

REMOVED FROM TB4-7

VIO

SW-9B

TB4

Fig. 33 — Modulating Power Exhaust and Inlet

Guide Vane Differential Pressure Switch

(Sizes 034-048)

Fig. 34 — Inlet Guide Vane Differential

Pressure Switch and Variable Frequency Drive

Duct Pressure Transducer (Sizes 054-104)

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 auxiliary control box of the unit. See Fig. 33 and 35. Use a nomi-

⁄8-in. plastic tubing.

nal

For instructions on adjusting BP control set points, refer to Start-Up, Modulating Power Exhaust section in this book.

START-UP

Initial Check

IMPORTANT: Do not attempt to start unit, even momentarily,until all items on the Controls Start-Up Checklist (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 applicable controls programmed to the default values.

5. Check and adjust unit set points. See Table 9.

6. Check tightness of all electrical connections.

7. Perform quick test (see Quick Test Program section on

page 31).

Fig. 35 — Modulating Power Exhaust Differential

Pressure Switch (Sizes 054-104)

Table 9 — Potentiometer Inputs and Ranges

POTENTIOMETER DESCRIPTION LOCATION

P2*

P3 Reset Limit

P4†

DLCM-P1 DLCM-P2 DLCM Board 0 to 49% None

P5*

P7**

*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), ora5to20k-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.

Supply Air

Set Point

Economizer

Position

Demand Limit,

Single-Step

Demand Limit,

2-Step

Minimum Economizer

Position

Warm-Up

Set Point

Reset

Temperature

Display

Board

Economizer

Motor

Accessory

Board

Main Control Box 0 to 100% None

DLCM Board 50 to 100% None

Accessory Board 0 to 100% None

Accessory Board 40 to 80 F

Reset Board 40 to 100 F None

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 factory set and should not be changed; changing the factory setting 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.

Table 10 — Conﬁguration Header and

DIP Switch Factory Settings

UNIT SIZES

JUMPER OR SWITCH NO.

1 ▫ Off ▫ Off ▫ Off 2 n Off n Off n Off 3 n On/Off* n On/Off* n On/Off* 4 ▫ On/Off* ▫ On/Off* n On/Off* 5 ▫ Off ▫ Off ▫ Off 6 n Off n On n On 7 ▫ On ▫ Off ▫ Off 8 n Off n Off n Off

DIP — Dual, In-Line Package

▫ — Broken Jumper (open circuit) n — Unbroken Jumper (closed circuit)

*Depending on factory-installed options or ﬁeld-installed accessories.

034-038, 048-088

Header

Position

LEGEND

Switch

Position

UNIT SIZE

Header

Position

044

Switch

Position

UNIT SIZE

Header

Position

104

Switch

Position

CONTROL

VALID

RANGE

45 to 70 F 0 to 100% None (0 if P2 is bad)

0 to 80 F None (limited to 70 F maximum)

45Fif-22F<P1<45F 70FifP1>70FORIFP1<-22F

40Fif0°F<P6<40FORIFP6<95F OR IF P6 < 0 80Fif80F<P6<95F

Table 11 — Conﬁguration Header Jumpers

JUMPER

NUMBER

1,2 Unit Type ▫n VAV Rooftop Unit

3,4,5 Qty Compressors n▫▫ 2 Compressors

6 Expansion Valve n TXV 7 Power Frequency ▫ 60 Hz 8 Not Used n No Signiﬁcance

TXV — Thermostatic Expansion Valve VAV — Variable-Air Volume

▫ — Broken Jumper (open circuit) n — Unbroken Jumper (closed circuit)

FUNCTION

LEGEND

DIP Switches — The DIP switches conﬁgure the unit

for several factory-installed options and ﬁeld-installed accessories, plus factory unloaders. The DIP switches are located 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 factory settings of the switch positions.

Disconnect control power before changing the settings of the DIP switches. To disconnect control power, open the control circuit breaker.

DEFAULT VALUE

FACTORY

SETTING

MEANING

DIP SWITCH NO. 1 — Supply Air Set Point (SASP) Reset Type. Factory setting is OFF. Do not change.

DIP SWITCH NO. 2 — SASP Reset Enabled. Factory setting is OFF (no SASP reset enabled). If SASP reset has been installed, enable it by changing switch position to ON.

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.

DIP SWITCH NO. 5 — Demand Limit. Factory setting is OFF (demand limit not enabled). If Demand Limit (singlestep or 2-step accessory) has been installed, change this switch to ON.

DIP SWITCHES NO. 6 AND NO. 7 — Unloader Conﬁguration. These are factory set to match unit size. Conﬁrm settings per Table 12. Change only if in error.

Table 12 — DIP Switches

SWITCH

NO.

2 3 Economizer

6,7 Unloaders

8 Not Used Off No Signiﬁcance

DIP — Dual, In-Line Package

*Controlcircuit breaker must beoff before changingthe setting ofthe DIP switch.

†No economizer.

**And/or electric heat (50FK,JK units without plenum only).

FUNCTION

Morning

Warm-Up

Demand

LEGEND

Reset Mode

Reset

Select

Limit

SWITCH

POSITION*

Off On

Off

Off, Off On, Off Off, On

MEANING

Space or Outdoor-Air Reset (DO NOT CHANGE)

Reset Used Reset Not Used

Enable Economizer Disable Economizer†

Enable Morning Warm-Up** Disable Morning Warm-Up**

Enable Demand Limit Disable Demand Limit

No Unloaders 1 Unloader 2 Unloaders

Adjusting Set Points — Set points for unit operation

are established via potentiometer settings. Set points for Supply Fan controls are set at the VFD keypad (if installed) or at the IGV differential pressure switch (DPS1) (if IGV option installed). Set points for modulating power exhaust (option or accessory) are set at the differential pressure switch (DPS2).

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 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 potentiometer, which may not be the same as the valid range.

Potentiometer inputs and ranges are summarized in Table 9. Information on individual set point potentiometers (including function, location and range data) are shown below:

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.

ECONOMIZER MINIMUM POSITION (P5) — This potentiometer 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%.

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 discussion of SASP Reset operation.

RESET LIMIT (P3) — Used in conjunction with P7 potentiometer, this potentiometer establishes the maximum temperature for the modiﬁed SASP value during the Reset function. This potentiometer has a valid range of 0° to 80 F.

DEMAND LIMIT, SINGLE-STEP (P4) — This potentiometer establishes the maximum amount of compressor capacity permitted by the unit control when single-step demand limit operation is implemented (by closing contact set to potentiometer 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.

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.

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 potentiometers are located on the DLCM. Potentiometer DLCM-P1 establishes the maximum amount of compressor capacity available 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 capacity is reduced by the amount set on potentiometer P2.

MORNING WARM-UP (P6) — This potentiometer establishes 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 programmed 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.

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 differential 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 control 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. 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 0.17 in. wg when set point is at minimum 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 adjust null span, turn a 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.

*The inletguidevanedifferentialpressureswitchforthe034-048units

is located in the back of the unit in the auxiliary control box. Its location is not shown in this ﬁgure.

Fig. 36 — Inlet Guide Vane Motor,

50FK,JK034-074 Units

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 keyboard 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 operates in proper rotation regardless of the phase sequence to the unit. If, upon start-up, the outdoor fans operate backwards 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.

T oset 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 percentage of the frequency range. Refer to Table 13. The set point value is a percentage of the maximum output frequency. Locate the duct static pressure closest to that desired and use the corresponding set point value. If necessary, interpolation between duct static pressures is permissible.

Factory-installed optional VFD is located near the supply fan and motor. During any service work or programming 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 install the accessory VFD remote display accessory.

*The inletguidevanedifferentialpressureswitchforthe034-048units

is located in the back of the unit in the auxiliary control box. Its location is not shown in this ﬁgure.

Fig. 37 — Inlet Guide VaneMotor,48FK,JK, 50FY,JY,

and 50FJX,FJY,FKX,FKY034-074 Units

Fig. 38 — Inlet Guide Vane Motor,

Size 078-104 Units

CAPACITOR

NULL ADJUSTMENT

SET POINT ADJUSTMENT

SET POINT INDICATOR

COM — Common N.C. — Normally Closed N.O. — Normally Open

LEGEND

NULL DECREASE

SET POINT

DECREASE

PLANE

COM N.C. N.O.

Fig. 39 — Differential Pressure Switch for Inlet Guide

Vane and Static Pressure Control Option and

Modulating Power Exhaust Option

HZ PERCENT SECONDS KW/AMPS/VOLTS

SETUP

PROGRAM

RUN

MONITOR

READ

STOP

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.

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 indicates 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 programming can be changed.

7. Change VFD set point according to Table 14 shown below.

8. Once the program changes are completed, turn offIFCB.

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 indicates 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.

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,Variable Frequency Drive section (page 52).

WRITE

LOCAL/REMOTE

SPEED CTRL

RESET

MANUAL/AUTO

RUN MODE

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 necessary, interpolation between duct static pressure values is permissible.

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.

P24 RES RR F R S1 S2 S3 S4 RCH P24 LOW LOW

ST FM AM CC CC RX PP IV FP FLC FLB FLA

REMOVE JUMPER

Fig. 41 — Jumper Removal to Disable Motor

Table 13 — VFD Set Point (Frequency Command) for Duct Pressure

PRESSURE

(in. wg)

0.00 0 4.0 2.00 24 10.4

0.25 3 4.8 2.25 27 11.2

0.50 6 5.6 2.50 30 12.0

0.75 9 6.4 2.75 33 12.8

1.00 12 7.2 3.00 36 13.6

1.25 15 8.0 3.25 39 14.4

1.50 18 8.8 3.50 42 15.2

1.75 21 9.6

VFD SET POINT (Hz)

CONTROL SIGNAL

(mA)

PRESSURE

(in. wg)

VFD SET POINT

(Hz)

Table 14 — Changing the VFD Set Point (Frequency Command)*

KEY OPERATION LED MESSAGE EXPLANATION

XX.X or OFF

↓ 60.0 Pressing arrow key once will display the current frequency setpoint

↓↑ 45.0 (ﬂashing) Pressing up/down arrow keys changes the desired setpoint

R/W FC and 45.0 (ﬂashing)

XX.X or OFF

*Choose set point from Table 13 according to desired duct pressure.

Standard Monitor Mode (output frequency). If drive is disabled, display will read 9OFF9. If enabled, display will show current output frequency

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.

Standard Monitor Mode (output frequency). If drive is disabled, display will read 9OFF9. If enabled, display will show current output frequency

CONTROL SIGNAL

(mA)

Modulating Power Exhaust (Option or Accessory)

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 differential pressure switch (DPS).

SIZE 034-048 UNITS — The modulating power exhaust differential 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 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. 33.

SIZE 054-104 UNITS — The modulating power exhaust differential pressure switch is mounted below the auxiliary control box next to the access door labeled FILTER SECTION. See Fig. 35.

— The Modulating Power Exhaust system will main-

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.

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 control) 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.

3. Initialization mode begins (see Operating Information section 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-

88diagnostic routine. When this is in effect, an will ap-

pear in the display screen. Refer to Quick Test Program section below, for instructions on completing the Quick Test program.

Quick Test Program — Turn on power to unit.

IMPORTANT: The ﬁeld-supplied switch (or timeclock) must be closed to put unit into the occupied mode.

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 options, thermistors, and control switches are in proper working order.

When unit control circuit is switched to Occupied mode,

20a will appear on the display. Immediately press display button once. An will appear on the display and alarm 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 showingondisplay for more than 2 minutes. If display button is not pressed within

this time period, control will attempt to start unit.

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 numeral). The action code number is one or 2 digits with no decimal point(s).

IMPORTANT:Once quick test is initiated, display button 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.

To recheck any step in quick test program, control must be recycled by turning unit control switch off for a few seconds, 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.

The quick test program is divided into 3 sections as described below and shown in Tables 15-17.

1. Quick TestSteps 1.-1.3. — Unit Conﬁguration and Switch

Check 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 cannot be changed in the ﬁeld. The DIP switch assembly contains 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.

2. Quick Test Steps 1.4.-2.3. — Thermistor and Set Point

Potentiometer Check 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 display code for good sensors and potentiometers is 1.Adisplay code of 0 indicates a faulty potentiometer, thermistor or wiring. A 0 display also indicates that option is not being used.

Table 16 shows thermistor and set point potentiometer functions and quick test display codes.

Table 15 — Quick Test, Unit Conﬁguration and Switch Check

QUICK

TEST

STEP NO.

1.0.

NORMAL

DISPLAY

2 1

0 or 1

DESCRIPTION CONTROL SWITCH

Type Unit — Air-Cooled VAV Conﬁguration Header No. of Compressors Conﬁguration Header

No. of Unloaders (034,038,048-088)

(044, 104) 60-Hertz Power Conﬁguration Header

0 — No Reset (Switch Off) 1 — Reset On (Switch On)

0 — No Economizer (Switch Off) 1 — Economizer On (Switch On)

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

1 — Low-Pressure Switch Closed Low-Pressure Switch 1

DIP Switch No. 6 and 7

DIP Switch No. 2

DIP Switch No. 3

DIP Switch No. 4

DIP Switch No. 5

1.1.

1.2.

1.3.

LEGEND

DIP — Dual, In-Line Package EC — Enthlapy Control VAV — Variable Air Volume

*Units are not equipped with oil pressure switches.

1 1

1 — Low-Pressure Switch Closed Low-Pressure Switch 2 No Circuit 1 Oil Pressure Switch None* No Circuit 2 Oil Pressure Switch None*

Table 16 — Quick Test, Thermistor and Potentiometer Check

QUICK

TEST

STEP NO.

1.4.

1.5.

1.6.

1.7.

1.8.

1.9.

2.0.

2.1.

2.2.

NORMAL

DISPLAY

DESCRIPTION

1 — Thermistor OK 0 — Thermistor Faulty

1 — Thermistor or Potentiometer OK 0 — Thermistor or Potentiometer Faulty or

Option not used

1 — Potentiometer OK 0 — Potentiometer Faulty

1 — Potentiometer OK 0 — Potentiometer Faulty or Option not used

THERMISTOR OR

POTENTIOMETER*

Supply Air Thermistor (T1)

Return Air Thermistor (T2)

Circuit 1 Condenser Thermistor (T3)

Circuit 2 Condenser Thermistor (T4)

Accessory Space Temperature Thermistor (T10) or Accessory Reset Potentiometer (P7)

Supply-Air Set Point Potentiometer (P1)

Accessory Reset Limit Potentiometer (P3)

Accessory Demand Limit Potentiometer (P4)

Minimum Position Economizer Potentiometer (P5)

2.3.

*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.

1 — Potentiometer OK 0 — Potentiometer Faulty or Option not used

Warm-Up Set Point Potentiometer (P6)

Table 17 — Quick Test, Output Relay Check

QUICK

TEST

STEP NO.

2.4.

2.5.

2.6.

2.7.

2.8.

2.9.

3.0.

3.1.

3.2.

3.3.

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.

NORMAL DISPLAY

1 1

0 then 1 then 0

0 0

0 then 1 then 0

DESCRIPTION RELAY NUMBER

1 — Open Economizer or Open Relay if no Economizer K7 1 — Close Economizer or Close Relay if no Economizer K8 1 — Energize Fan Relay and Heat Relay K9* and K10 Energize Stage 1 Condenser Fan(s) K11 Energize Stage 2 Condenser Fan(s) K12 Energize Compressor 1† K1 Energize Unloader 2; Not Used (044, 104) K2 Energize Unloader 1 K3 Energize Compressor 2† K5 Not Used K6

Table 18 — Sensor Resistance Values

TEMP

RESISTANCE

(F)

(Ohms)

−60 362,640 45 11,396 150 1,020

−55 297,140 50 9,950 155 929

−50 245,245 55 8,709 160 844

−45 202,841 60 7,642 165 768

−40 168,250 65 6,749 170 699

−35 139,960 70 5,944 175 640

−30 116,820 75 5,249 180 585

−25 98,420 80 4,644 185 535

−20 82,665 85 4,134 190 490

−15 69,685 90 3,671 195 449

−10 58,915 95 3,265 200 414

−5 50,284 100 2,913 205 380 0 42,765 105 2,600 210 350 5 36,475 110 2,336 215 323

10 31,216 115 2,092 220 299 15 26,786 120 1,879 225 276 20 23,164 125 1,689 230 255 25 19,978 130 1,527 235 236 30 17,276 135 1,377 240 219 35 14,980 140 1,244 40 13,085 145 1,126

TEMP

(F)

RESISTANCE

(Ohms)

TEMP

(F)

RESISTANCE

(Ohms)

3. Quick Test Steps 2.4.-3.3. — Output Relay Check These quick test steps allow microprocessor to check

output signals from relay boards in unit control system. In addition, operation of all the condenser fans, compressors, and economizer (if equipped) are checked at each step.

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 startup, 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 successfully completed (Steps 2.9. and 3.2.). The 1 indicates that was tested.

Fan and compressor operating sequence for quick test Steps 2.4. through 3.3. are shown in Table 17.

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.

OPERATING INFORMATION

DigitalDisplay —

LED display located on the display board to display operational information and diagnostic codes.

CODES 0 THROUGH 8, CAPACITYSTEPS — 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.

Capacity steps are directly related to pin terminal connector J6 output. At step zero, the unit has no mechanical cooling 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

The VAV control system uses a 2-digit

load if the outdoor enthalpy is good. As long as the outdoorair 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.

CODES 20 THROUGH 30 AND 88, OPERATIONALSTATUS — These codes indicate special operational modes, such as initialization, morning warm-up, temperature reset, demand limit, or an internal failure of the board. Codes 23-25 and 27-29 are not used on these units.

Initialization — When the control is turned on, the display shows a for approximately 2 minutes to indicate that the

control is in the initialization mode. During this time, the economizer dampers open and close to determine the resistance range of the economizer position potentiometer (P2) for full economizer operation. The processor loads the necessary constants for proper unit operation and checks the thermistors and other potentiometers for their values and validity. After the initialization period, the display screen goes blank until the display button is pressed. If the display button is pressed during the 2-minute initialization period, the control goes into the Quick Test mode.

Temperature Reset — If the unit is equipped with the accessory temperature reset package, and DIP switch 2 is in the ON position, the unit will reset the supply-air temperature to a calculated value when necessary. When this condition is in effect, a will appear in the display.

Demand Limit — If the unit is equipped with the accessory demand limit control module or the ﬁeld-supplied, singlestep 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 will

appear in the display. Morning Warm-Up —If the morning warm-up heat routine

is enabled using DIP switch 4, and conditions of the occupied space warrant, the unit will begin the morning warm-up

routine. When this condition is in effect, a will appear

in the display. Internal Failure — If the unit detects an internal fault (such

as a time measurement failure), or detects an incorrect voltage on an input channel, a will be displayed, and the

unit will shut down. Quick Test — If the display button is pressed during the

initialization period of the processor, the unit will run its selfdiagnostic routine. When this is in effect, an will appear

in the display screen. CODES 51 THROUGH 87, DIAGNOSTIC INFORMA-

TION — These codes indicate diagnostic information when there is a unit problem such as a faulty thermistor, potentiometer, or compressor fault. Refer to Diagnostic Codes section 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.

Under normal operation, only the stage number is displayed when the display button is pressed. If a status or overload code is displayed, the display will rotate every 2 seconds 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.

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 replaced 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 begin its initialization mode.

A will appear in the display screen, and the initialization 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 economizer position potentiometer (P2). The processor loads the necessary constants for unit operation, and also checks the thermistors and other potentiometers for their values and validity. After the initialization period, the screen goes blank until the display button is pressed.

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.

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 resistance 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

warm-up routine, and a will be displayed.

Unit heat will be energized through the heat interlock relay (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 temperature reaches the morning warm-up set point (P6). Once morning warm-up has been terminated, the unit cannot return 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.

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 economizer will move to the minimum position determined by potentiometer 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 supplyair temperature of P1 ± 2° F by modulating the economizer dampers.

No mechanical cooling will take place until the economizer 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.

Compressors, unloaders, and condenser fans will be cycled to maintain a supply-air temperature 2° F below the potentiometer P1 set point once the mechanical cooling stages begin. 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 circuit, the low-pressure switch will be bypassed for 120 seconds to prevent nuisance trips of the low-pressure switch. After start-up, a low-pressure trip will be ignored for 30 seconds by the processor.

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:

Stage 1 Relays K1, K2, and K3 are energized. Compressor

no. 1 starts with both unloaders energized. Compressor no. 1 runs at

⁄3capacity. The crankcase heater for this compressor has been deenergized, and the ﬁrst stage of condenser fans have been energized. 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. The compressor is now operating at

⁄3capacity.

Stage 3 Relay K1 is energized. Compressor no. 1 is fully

loaded.

Stage 4 Relays K1, K2, K3, and K5 are energized. Com-

pressor no. 1 is running at

⁄3capacity, and compressor 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

no. 1 is running at

⁄3capacity, and compressor

no. 2 is running at full capacity.

Stage 6 Relays K1 and K5 are energized. Both compres-

sors are running fully loaded.

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 processor 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).

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 temperature 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 condensing 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.

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 sequence is as follows:

Stage 1 Relays K1 and K3 are energized. Compressor

no. 1 starts with the unloader energized. Compressor no. 1 is running at

⁄2capacity.The crankcase heater on compressor no. 1 has been deenergized, and the ﬁrst stage condenser fan has been energized. Outdoor (condenser) fan motor no. 1 (OFM1) has started.

Stage 2 Relay K1 is energized. Compressor no. 1 is fully

loaded.

Stage 3 Relays K1, K3, and K5 are energized. Compres-

sor no. 1 is running at

⁄2capacity, and compressor 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 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 sequence is as follows:

Stage 1 Relays K1 and K3 are energized. Compressor

no. 1 starts with unloader energized. Compressor no. 1 runs at

⁄3capacity.The crankcase heater for this compressor has been deenergized, and ﬁrst stage of condenser fans has been energized. Outdoor (condenser) 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-

sor no. 1 runs at

⁄3capacity 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.

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

⁄3capacity and compressors no. 2 and no. 4 are running at full capacity. The crankcase heater on compressor no. 4 is deenergized. 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.

Compressor no. 1 runs at

⁄3capacity and compressors 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 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 microprocessor based on condensing temperature input from either circuit’s T3 or T4 thermistor.

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 accessory 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 running without a call for mechanical cooling. Thermistors T3 and T4 provide the condensing temperature information to the processor. These VAV rooftop units have dual refrigeration 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 number 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 thermistor T3 or T4 senses a temperature greater than 125 F (278 psig), in which case all condenser fans are started.

During start-up, if the outdoor ambient is above 70 F (as sensed by thermistor T3 or T4), the ﬁrst-stage, processorcontrolled fans are turned on to prevent excessive discharge pressures.

034 AND 038 UNITS 044 AND 048 UNITS

LEGEND

OFM — Outdoor (Condenser) Fan Motor

Fig. 42 — Component Arrangement, 034-048 Units

054, 064 UNITS

074, 078 UNITS

054-088 UNITS

088, 104 UNITS

Fig. 43 — Component Arrangement, 054-104 Units

104 UNITS

Supply Fan Control with IGV — In most VAVunits,

the supply fan static pressure is controlled by inlet guide vanes. The inlet guide vanes operate independently from the microprocessor. The supply static pressure is controlled by a differential pressure switch. If the unit is equipped with a return fan, building pressure is controlled by another differential pressure switch.

For example, assume that set point on supply fan differential 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 position; 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 depends 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 result in a smaller pressure ﬂuctuation than if it is set at maximum position.

Supply Fan Control with VFD — When equipped

with the VFD option, the supply fan static pressure is controlled by modulating the fan wheel speed. The VFD operates independently from the microprocessor.A duct pressure transducer monitors duct static pressure. The transducer output (4 to 20 mA) is directed into the VFD. The VFD adjusts supply fan motor speed (which changes wheel speed) as measured 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.

NOTE: The VFD will always provide the proper phase sequence 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.

Modulating Power Exhaust (Option or Accessory except FY,JY units)

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 horizontally out the back of the unit through individual barometric 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 differentialpressure switch (DPS). Available 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 combination 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, auxiliary 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 contactor PEC2. Fan motor no. 2 starts and runs. Increased exhaust airﬂow will lower space pressure, causing DPS to drive PEDM back towards its closed position, until the set point is achieved.

If space pressure decreases until PEDM position is reduced to 10% of open position, PEDMS will open, deenergizing fan contactor PEC2 and shutting off fan no. 2.

— The power exhaust as-

Unit Staging — Compressor loading and unloading se-

quences are shown in Table 19.

Fig. 44 — Modulating Power Exhaust Component Locations; Sizes 034-048

Fig. 45 — Modulating Power Exhaust Component Locations; Sizes 054-104

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

Table 19 — Compressor Loading and Unloading Sequences

SIZE 034 UNITS

COOLING

STAGE

0 OFF OFF OFF OFF 0 0 1 ON ON ON OFF 2 17 2 ON ON OFF OFF 4 33 3 ON OFF OFF OFF 6 50 4 ON ON ON ON 8 67 5 ON ON OFF ON 10 83 6 ON OFF OFF ON 12 100

COOLING

STAGE

0 OFF OFF OFF OFF 0 0 1 ON ON ON OFF 2 14 2 ON ON OFF OFF 4 28 3 ON OFF OFF OFF 6 42 4 ON ON ON ON 6 72 5 ON ON OFF ON 8 86 6 ON OFF OFF ON 10 100

Comp 1

Lead Circuit Lag Circuit

Unloader

Lead Circuit Lag Circuit

Unloader

Comp 2

SIZE 038 UNITS

Comp 2

Active

Cylinders

Active

Cylinders

Percent

Capacity

Percent

Capacity

SIZE 044 UNITS

COOLING

STAGE

0 OFF OFF OFF 0 0 1 ON ON OFF 2 25 2 ON OFF OFF 4 50 3 ON ON ON 6 75 4 ON OFF ON 8 100

COOLING

STAGE

0 OFF OFF OFF OFF 0 0 1 ON ON ON OFF 2 19 2 ON ON OFF OFF 4 38 3 ON OFF OFF OFF 6 58 4 ON ON ON ON 6 62 5 ON ON OFF ON 8 81 6 ON OFF OFF ON 10 100

Comp 1

Lead Circuit Lag Circuit

Unloader

Lead Circuit Lag Circuit

Unloader

Comp 2

SIZE 048 UNITS

Comp 2

Active

Cylinders

Active

Cylinders

Percent

Capacity

Percent

Capacity

Table 19 — Compressor Loading and Unloading Sequences (cont)

COOLING

STAGE

0 OFF OFF OFF OFF 0 0 1 ON ON ON OFF 2 20 2 ON ON OFF OFF 4 40 3 ON OFF OFF OFF 6 60 4 ON ON OFF ON 10 80 5 ON OFF OFF ON 12 100

COOLING

STAGE

0 OFF OFF OFF OFF 0 0 1 ON ON ON OFF 2 17 2 ON ON OFF OFF 4 33 3 ON OFF OFF OFF 6 50 4 ON ON ON ON 8 67 5 ON ON OFF ON 10 83 6 ON OFF OFF ON 12 100

COOLING

STAGE

0 OFF OFF OFF OFF 0 0 1 ON ON ON OFF 2 14 2 ON ON OFF OFF 4 29 3 ON OFF OFF OFF 6 43 4 ON ON ON ON 8 71 5 ON ON OFF ON 10 86 6 ON OFF OFF ON 12 100

Comp 1 Unloader U1 Unloader U2 Comp 2

Lead Circuit Lag Circuit

SIZE 054 UNITS

SIZE 064 UNITS

SIZE 074, 078 UNITS

Active

Cylinders

Active

Cylinders

Active

Cylinders

Percent

Capacity

Percent

Capacity

Percent

Capacity

COOLING

STAGE

0 OFF OFF OFF OFF 0 0 1 ON ON ON OFF 2 16 2 ON ON OFF OFF 4 33 3 ON OFF OFF OFF 6 50 4 ON ON ON ON 8 66 5 ON ON OFF ON 10 83 6 ON OFF OFF ON 12 100

COOLING

STAGE

0 OFF OFF OFF OFF OFF 0 0 1 ON ON OFF OFF OFF 4 20 2 ON OFF OFF OFF OFF 6 30 3 ON ON OFF ON OFF 10 50 4 ON OFF OFF ON OFF 12 60 5 ON ON OFF ON ON 14 70 6 ON OFF OFF ON ON 16 80 7 ON ON ON ON ON 18 90 8 ON OFF ON ON ON 20 100

Comp 1 Unloader U1 Unloader U2 Comp 2

Comp 1 Unloader U1 Comp 3 Comp 2 Comp 4

Lead Circuit Lag Circuit

SIZE 088 UNITS

SIZE 104 UNITS

Active

Cylinders

Active

Cylinders

Percent

Capacity

Percent

Capacity

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, compressor 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.

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.

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.

• Unit supply-air temperature (T1) thermistor failure.

• Supply-air fan is not operating.

• High duct static pressure.

Single Circuit Stoppage — If a single circuit stops,

there are several potential causes:

• Open contacts in the compressor high-pressure switch.

• Low refrigerant pressure.

• Thermistor failure.

• Unit supply-air temperature thermistor (T1) failure.

• Compressor circuit breaker trip.

• Operation of the circuit blocked by the demand limit

function.

Table 21 — Operation Status Codes

CODE MEANING

□

0 cooling stages active

1 cooling stage active

2 cooling stages active 3 cooling stages active

4 cooling stages active

5 cooling stages active

6 cooling stages active

7 cooling stages active

8 cooling stages active Initialization mode (Allow 2 minutes

for initialization. To initiate Quick Test, press the Display button while 20 is displayed.)

Temperature Reset in effect

Demand Limit in effect

Morning Warm-Up in effect

Internal failure detected

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.

Evaporator fan does not run. 1. Circuit breaker open. Compressor does not run. 1. Circuit breaker is open.

Condenser fans do not turn on.

Cooling demand exists and economizer modulates, but compression is not operating.

Remote on-off function may be keeping controls off.

2. Inverter overload (if equipped).

2. There is no demand for cooling.

3. The control is locking out cooling operation.

4. Demand Limit in effect. Circuit breaker is open. Find cause and reset circuit breaker

Compression cannot be initiated until economizer damper is 90% open.

Check status.

1. Find cause and reset circuit breaker.

2. Find cause and reset.

1. Find cause and reset circuit breaker.

2. Correct operation.

3. Check rotating display for alarm codes. Resolve alarm cause and reset control by changing to standby and back to run mode.

4. Check Demand Limit Settings.

Correct operation.

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 energized whenever a diagnostic code is tripped. When a problem is suspected, always check the display ﬁrst for diagnostic information.

NOTE: Codes 53, 54, 57, 58, 61, 62, 65-69, 73, 74, and 77-80 are not used on these units.

IMPORTANT: The microprocessor memory and the display will be cleared if the power to the microprocessor 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 hazardous operating condition.

CODES 51, 52, 55, 56: COMPRESSOR F AILURE— If control relay (CR) opens while compressor should be operating, compressor will stop and microprocessor will energize alarm

52 55 56light and display a code of , , or (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.

Code 51 is for compressor 1, and Code 55 is for compressor 2. Codes 52 and 56 are used for compressors 3 and 4, respectively, on size 104 units.

The microprocessor has also been programmed to indicate a compressor failure if CR switch is closed when compressor is not supposed to be on.

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 energizes CR. If high-pressure switch opens during operation, CR will stop compressor and this will be detected by microprocessor through the feedback contacts.

Internal Thermostat — The internal thermostat in each 06D compressor is also wired in series with 24-v power that energizes CR. If thermostat fails or switch opens during operation of compressor, compressor will shut down and failure is detected through feedback contacts (size 034 and 038 only).

CR Failure — If CR fails with large relay either open or closed, microprocessor will detect this, lock compressor off, and indicate an error.

Relay Board Failure — If small 24-v relay on the relay board fails, microprocessor will detect this through feedback contacts and indicate an error.

Processor Board Failure — If hardware that monitors feedback switch fails and processor board fails to energize the relay board relay to ON position, an error may be indicated.

The control does not detect compressor circuit breaker failures.

WiringProblem — 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

51 55 52 56

59 60

63 64

70 Illegal unit conﬁguration Unit will not start Manual Conﬁguration error (see Note 1). 71

72 75

76 81

82 83 84 85 86 87

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.

Compressor 1 failure Compressor 2 failure Compressor 3 failure Compressor 4 failure

Loss-of-charge circuit 1 Loss-of-charge circuit 2

Low oil pressure circuit 1 Low oil pressure circuit 2

Supply-air thermistor failure Return-air thermistor failure Circuit 1 saturated condensing thermistor

Circuit 2 saturated condensing thermistor Reset temperature thermistor failure

Leaving-air set point potentiometer failure Economizer potentiometer failure Reset limit set point potentiometer failure Demand limit potentiometer failure Minimum economizer potentiometer failure Warm-up set point potentiometer failure

BY CONTROL

Circuit 1 shut off Circuit 2 shut off Compressor 3 shut off Compressor 4 shut off

Circuit 1 shut off Circuit 2 shut off

Unit shut off Use default value Unit shut off

Unit shut off Stop reset

Use default value Close economizer Stop reset Stop demand limit Close economizer Use default value

RESET

METHOD

Manual Manual Manual Manual

Manual Manual

Auto. Auto. Auto.

Auto. Auto.

Auto. Auto. Auto. Auto. Auto. Auto.

PROBABLE CAUSE

High-pressure switch or high discharge gas thermostat switch trip, compressor ground current . 2.5 amp or compressor board relay on when it is not supposed to be on. Wiring error between electronic control and compressor protection module.

This indicates either a low refrigerant charge, or a loss-of-charge switch failure.

Not used; Check jumper on processor board.

Thermistor or resistor failure, wiring error, or thermistor or resistor not connected to the processor board.

Potentiometer improperly connected, potentiometer setting out of range, potentiometer failure or wiring error.

CODES 59 AND 60: LOW-PRESSURE SWITCH — These codes are used to indicate a low-pressure switch failure.

The processor monitors the low-pressure switch. If the switch opens, either by low refrigerant charge, circuit failure, or wiring 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.

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 jumpered together or an error will occur. If these errors occur, check jumper between J2-1 and J2-2 for a code 63, or between J2-3 and J2-4 for a code 64 to be sure jumper is properly connected. To reset the circuit, the ON-OFF switch must be turned to OFF and then to ON position.

CODE 70: ILLEGAL UNIT CONFIGURATION — If the unit conﬁguration header is not installed and properly conﬁgured, 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 possible causes:

Thermistor or Resistor Failure — A shorted or open thermistor or resistor will cause the failure.

WiringFailure — 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: 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 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 components fail, reset will be terminated. This error will automatically 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.

CODE 82: LEAVING-AIR TEMPERATURE SET POINT POTENTIOMETER FAILURE— If leaving-air set point potentiometer (P1 — located on display board) fails, control will use a default value. A failure will cause an error code of

to be displayed on display board when display button is

pushed; alarm light will also be energized. A failure is determined by establishing a range of −22 F to 70 F as a valid range. Anything outside this range will be treated as a failure. If setting is outside the −22 F to 70 F range, alarm light

82will be energized and an error code of 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 automatically 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.

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 potentiometer and processor board or display board, a failure will result.

Potentiometer Failure — If potentiometer is shorted or open, a failure will result.

CODE 83: ECONOMIZER FEEDBACK POTENTIOMETER FAILURE — If potentiometer on economizer motor (P2) fails, control will use a default value of 0% and economizer outdoor-air dampers will close. The failure will en-

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.

Potentiometer Failure — If potentiometer is shorted or open, this will cause a failure.

Economizer Damper Stuck — The control has been programmed 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 potentiometer setting is less than 0° F or greater than 80 F,

alarm light will be energized, a diagnostic code of will

84 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 parallel 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).

Incorrect Potentiometer Setting — Apotentiometer turned fully clockwise or counterclockwise is outside the valid range and will result in a failure.

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 LIMITPOTENTIOMETER (P4) FAILURE — 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).

For both types of demand limit, the control uses only 80% of the total potentiometer resistance. If resistance of potentiometer is less than 10% or greater than 90%, alarm light

will be energized, a diagnostic code of 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 POTENTIOMETER FAILURE — If potentiometer P5 (on accessory board) setting is less than 0% or greater than 100%,

alarm light will be energized, a code of will be displayed 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.

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.

CODE 87: WARM-UPTEMPERATURE SET POINT FAILURE —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 returnair temperature to the warm-up set point. If warm-up function is used, DIP switch 4 must be in the ON position. The

potentiometer (P6) is located on the accessory board. If potentiometer is set at less than 0° F or more than 95 F, alarm

light will be energized, a diagnostic code of will appear on the display when display button is pushed, and control 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 diagnostic 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 accessory board, measured resistance is 3.3 Kohm.

The failure will automatically reset once potentiometer returns 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.

ThermistorTroubleshooting— The VA Vcontrol sys-

tem uses thermistors to measure temperatures of the entering and supply air, as well as the saturated condensing temperatures 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 signal applied across them any time the unit control circuit is energized. The voltage drop across the thermistor is directly proportional to the temperature and resistance of the thermistor.

To determine temperatures at the various thermistor locations, disconnect the thermistor from the processor board and measure the resistance across the appropriate thermistor using a high-quality digital ohmmeter. Use the resistance reading to determine the thermistor temperature.

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 operation 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.

ElectronicControls Checkout — The following will

help determine whether a processor board, a relay board, display set point board, accessory board, or 2-step demand limit module is faulty.

Before checking out any board, do the following:

1. At initial start-up, enter the Quick Test mode. This test

will determine if all components are connected and operating 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 section of unit; this chart will help determine probable cause of failure.

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.

Avolt-ohmmeter will be needed to troubleshoot boards.A digital meter is preferred but a Simpson 260 or equivalent will work.

To prevent damage to solid-state electronic components on boards, meter probes should only be placed on terminals and test points listed in following sections. Do not short the electrical components, and use extreme care while working on the processor board.

PROCESSOR BOARD CHECKOUT — Refer to Fig. 48 and 49 for location of terminal pins and test points.

Step 1 — CheckTransformerInput 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.

2. Turn control switch to ON position.

3. Check voltage at following terminals on pin terminal con-

nector J4:

TERMINALS VOLTAGE (AC)

1to2 15.3 to 20.9 4to6 16.2 to 22.0 5to6 8.1 to 11.0 5to4 8.1 to 11.0

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 11 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.

2. Negative probe on TP18.

3. Check voltage TP18 to TP11.

4. If voltage is greater than 13 vdc, reset power and recheck.

5. If voltage is still incorrect, replace processor board.

6. Turn power to ON position.

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, transformer, 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.

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.

3. Connect negative lead to TP18.

4. Turn power switch to ON position and press display button to enter Quick Test mode.

5. Check voltage between TP18 and each of the following test pins:

TEST PIN VOLTAGE (DC)

TP3 110 TP4 112

TP6 15 TP10 15 TP14 112 TP15 112

TP7 −5*

*If not using a digital meter, leads must be reversed.

LEGEND

J—Pin Terminal Strip TP — Test Pin

Fig. 48 — Processor Board Test Points

R9 R10 R11 R12 R13

C9 C10 C11 C12 C13

CR9 CR10 CR11 CR12 CR13

C1 C2 C3 C4 C5 C6 C7 C8

CR1 CR2 CR3 CR4 CR5 CR6 CR7 CR8

C19

C16

C18

C27

C15

C14

C21

C26

C25

C24

C23

C22

J5J6

6. If voltage is incorrect, replace processor board.

7. Turn power to ON position.

K1 K2 K3

LEGEND

CR — Control Relay J—Pin Terminal Strip K—Relay

Fig. 49 — Relay Board Test Points

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.

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 terminal connector J9, and check voltage from TP19 to terminal 14 on pin terminal connector J9.

5. If not 112 ± 1 vdc, replace processor board.

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 Testmode.

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.

Fig. 50 — Relay Board Pin Terminal Connector (J9)

Table 23 — Voltage Reading

QUICK TEST

STEP NO.

1.-2.3. 00000000000012

2.4. 000000120000012

2.5. 000000012000012

2.6. 0000000120120012

2.7. 0000000120012012

2.8. 0000000120001212

2.9. 12 00000012000012

3.0. 0 12 0000012000012

3.1. 0012 000012000012

3.2. 000012 0012000012

3.3. 0000012 012000012

NOTES:

1. Pins shown in boldface type will only be energized for 10 sec-

onds.All other pins willbeenergizedcontinuously while at the proper quick test step. The control will only stay in the Quick Testroutine for 10 minutes unless the display button is pressed.

2. Acceptable range for the voltage reading:

0v—0to4v

12v—11to13v

3. If any of these voltages are not measured, replace the processor

board.

12345678910111213

J9 PIN NUMBERS

5. Place the other lead on terminals shown in table below, and check voltage at pin terminals on pin terminal connector J10 (see Fig. 51 for pin terminal connector J10 details):

PIN TERMINAL VOLTAGE (DC)

17 5 18 5 20* 2.5 22* 2.5 24 5

*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 7 — Potentiometer Connection Checkout.

1. Turn power to OFF position.

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 Testmode.

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* 2.5

3 5 6 5

8* 2.5 10* 2.5 12 5 13* 2.5 14* 2.5

*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 connector J1, and mark them for later replacement.

3. Connect the 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 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.

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 — DisplayBoard Pin T erminalConnector(J10)

Table 24 — Pin Terminal Connector J1 Voltages

TERMINAL

1 2 6 7 8 9

11 12 13 14 15 16 17 18 19 20 21

VOLTAGE

(vdc ± 0.25 v)

0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5

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 removed in Step 2.

8. Turn power to ON position.

Table 25 — Pin Terminal Connector J2 Voltages

TERMINAL

1 2 3 4 7 8

9 10 13 14 15 17 18 19 20 21 22 23 24

VOLTAGE

(vdc ± 0.25 v)

0 5 0 5 0 5 0 5 0 5 5 5 5 5 5 5 5 5 5

If Steps 1 through 9 have been competed and the unit still

will not function properly, replace the processor board. 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 attached to the relay board.

The following procedure can be used to check out the operation of the relays. To do this, turn the control ON/OFF switch to the OFF position, and remove the wiring connectors connected to pin terminal connectors J5 and J6. Set the meter for resistance. If the contacts do not close at the required quick test step, check the relay outputs from the processor 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.

6. If these resistances are not correct and relay board out-

puts from processor board have been checked out, replace 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 Testmode.

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 Processor Board Checkout section on page 48, replace relay

board. DISPLAY BOARD CHECKOUT Step 1 — Check the Output Voltage from Processor Board

to the Relay Board — Refer to Step 6 — Display Board Connection Checkout section on page 49.

Table 26 — Terminal Strip J6 Connection

Resistance Reading

QUICK TEST

STEP NO.

1. to 2.3. ````````

2.4. ``````0`

2.5. ```````0

2.6. ````````

2.7. ````````

2.8. ````````

2.9. 0 ```````

3.0. ` 0 ``````

3.1. ``0` ` ```

3.2. ````0```

3.3. `````0``

LEGEND ` — 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.

12345678

J6 PIN NUMBERS

Table 27 — Terminal Strip J5 Connector

Resistance Reading

QUICK TEST

STEP NO.

1. to 2.5. ````0

2.6 00``0

2.7. 0 ` 0 ` 0

2.8. 0 `` 00

2.9. to 3.3. 0 ```0

LEGEND

` — Inﬁnity

12345

J5 PIN NUMBERS

Step 2 — Check the Display LEDs

1. Enter Quick Test mode.

2. If is not displayed, replace display board.

Step 3 — Check Set Point Potentiometer — Advance the display 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.

ACCESSORYBOARD 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:

1. Remove the accessory board connector from the processor 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 obtained 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 economizer minimum position potentiometer is turned clockwise, resistance should increase from 0 to approximately 3,400 ohms.

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.

IMPORTANT: Be careful to avoid damaging the connector or the processor board when taking the voltage readings.

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

NOTE: Voltage should vary between 0.5 vdc and 2.5 vdc as the setting of P2 is varied between 0% and 49%.

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%.

NOTE: If the voltages listed in these 3 tests are not obtained during testing, the DLCM board must be replaced.

Enthalpy Sensor Checkout — Totest operation of

enthalpy sensor, see Table 28.

Table 28 — Enthalpy Sensor Checkout

TEST EXPECTED RESULT

Outdoor-air sensor:

Enthalpy sensor + terminal should be connected to + terminal on motor. Connect the positive terminal of a DC milliammeter to the S terminal of the sensor and the negative terminal of the meter to S terminal of the enthalpy board.

Indoor-air sensor:

AND RESPONSE

Milliammeter reading should be between 3 and 24 mA if sensor is operating correctly. If reading is 0 mA, the sensor is either wired backwards or is defective.

Economizer Motor — All control of the motor (i.e.,

enthalpy changeover, minimum position control and mixed air control) is accomplished from the main unit microprocessor through a relay board. Service and installation instructions for the unit should be consulted to verify proper operation of these controls. The economizer motor may be checked out separately. See Fig. 52 for VAV economizer motor connection information.

Motor Test 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 Motor drives open; if not,

2 at motor replace motor. B Motor Test B Expected Result and Response

Jumper 1 to Motor drives closed; if not, 3 at motor replace motor.

LIMIT SWITCHES

CAPACITOR

CW WINDING (OPEN)

CCW WINDING (CLOSE)

BRAKE WINDING

FEEDBACK POTENTIOMETER

LEGEND

CCW — Counterclockwise CW — Clockwise

Fig. 52 — Damper Motor Connection Diagram (VAV)

ECONOMIZER

MOTOR

AUX. SWITCH

BLU

RED

YEL

Variable Frequency Drive

Factory-installed optional VFD is located near the supply fan and motor. During any service work or programming at the VFD, operation of the fan and motor is not desirable. Either disable the supply fan or install an accessory VFD remote display.

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 default values.

ST ANDARDTRANSDUCER CONTROL — The VFD monitors and controls duct pressure (DP) via a differential pressure 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 ﬁeldconnected to the duct pressure pick-up (ﬁeld-supplied and installed in the supply duct).

The DP transducer monitors the static pressure in the supply duct and providesa4to20mAsignal 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 adjusts its output to the supply fan motor to maintain the desired DP set point. When operating with the factory-standard DP transducer, the internal PID logic of the VFD is enabled.

EXTERNAL SIGNAL CONTROL — If the VFD is to be controlled by an external control system other than the factory supplied pressure transducer, the internal PID logic function 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).

3. Remove factory-supplied cable attached to IV and CC.

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.

8. Reprogram the VFD to accept an external reference (in

the Utility parameters group [Gr.Ut], set parameter item Fnod [no.312] = 4).

9. Enable supply fan motor and return power to the unit. SUPPLY FANMOTOROVERLOAD 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 original factory selection, the overload value may need to be changed by the service person. Contact your local Carrier representative for assistance in determining the proper overload setting.

NOTE: Variable frequency drive size is matched to factoryinstalled motor size. Do not increase motor size without also changing to equivalent VFD size.

Table 29 — Carrier Default Program Parameter Values

PARAMETER GROUP PARAMETER DEFAULT VALUE

ACC1 60.0 Sec DEC1 60.0 Sec

UL 60.0 Hz

LL 10.0 Hz*

Luln 1

P3 20%

SEtP

(Setup)

Gr.F

(Fundamental)

Gr.Fb

(Feedback)

Gr.SF

(Frequency Settings)

Gr.Pn

(Panel Control)

Gr.St

(Terminal Selection)

Gr.Pr

(Protection)

Gr.Ut

(Utility)

*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.

F-P3 0.0 Hz

P4 100%

F-P4 60 Hz

tHr1 See Table 31

StC1 0

StL1 110% OLN 1

tYP 5* FH 60 Hz

Pt 2

FbP1 1*

Fbln 2

GP .30

Gl 2 sec

GA 0

GFS 80

P1LL 10

PuL 1 PuUl 10 PuLL 10

Fsor 60 Hz

Sr.n 1* (054-104 only) SrN1 0* (054-104 only)

Fr 0*

1t 1 1t0 0 1t1 56 1t2 13 1t3 3 1t4 10

UuC 1*

UuCt 2

ArSt 3 Cnod 1* bLSF 1* (054-104 only) Fnod 2* bLPn 1*

P24

RES

P24

FLC

SIRXS2

4-20mA

FLB

LOW

FLA

RCH

Fig. 53 — Variable Frequency Drive Terminal Block

(Size 034-048 Units)

P24

RES

P24

FLC

SIRXS2

4-20mA

FLB

LOW

FLA

RCH

Fig. 54 — Variable Frequency Drive Terminal Block

(Size 054-104 Units)

VFDOperation — 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 (reverse rotation, factory supplied) or terminals F-CC (forward rotation, factory supplied).

UNIT SIZES ROTATION JUMPER

034-048 Reverse R-CC 054-074 Forward F-CC 078-104 Forward F-CC

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 display module.

When power is ﬁrst supplied to the VFD, the display automatically 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.

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.

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 settings (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.

The Carrier-factory settings are maintained as user settings. 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 defaults 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.

Table 30 — Required User Adjusted Defaults

SIZES ITEM

All Motor overload settings (see Table 31)

054-104

1. Check jumper CC-F

2. Gr.UT/bLSF = 1

3. Gr.SF/Sr.n = 1

4. Gr.SF/SrN1 = 0

5. SEtP/tYP = 5 (Save User Settings)

3. Emergency stop jumper is installed from terminals S4-CC (factory supplied).

4. A4 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).

7. Programmed according to Carrier defaults.

8. Duct Pressure set point established by user, or use factory default (30 Hz indicating 2.50-in. wg) (see Table 13).

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 package has been installed).

Table 31 — Motor Overload Settings

UNIT

VOLTAGE

UNIT 48/50

FK,FY, JK,JY 5 And N 82.0

FKX,FKY,

JKX,JKY

LEGEND

IFM — Indoor Fan Motor

DESIGNATION

Model No.

Position 12

5 And Q 86.0 6 And A 80.0 6 And K 80.0 6 And Q 80.0 6 And Q 80.0 6 And T 78.0

AND

IFM HP

DESIGNATION

Model No.

Position 15

Unit Wiring — A typical wiring schematic is shown in

Fig. 55.

tHr1

SETTING

LEGEND AND NOTES FOR FIG. 55

ALM — Alarm C—Contactor CB — Circuit Breaker CCB — Control Circuit Breaker COMP — Compressor CH — Crankcase Heater CR — Control Relay DPS — Differential Pressure Switch DPT — Discharge Pressure Transducer EAT — Enering-Air Temperature EC — Enthalpy Control ECR — Economizer Close Relay EOR — Economizer Open Relay EQUIP — Equipment FS — Fan Status Switch GND — Ground HIR — Heat Interlock Relay HPS — High-Pressure Switch HR — Heater Relay HTR — Heater IDC — Induced Draft Contactor IDM — Induced Draft Motor IFC — Indoor (Evaporator) Fan Contactor IFCB — Indoor Fan Circuit Breaker IGV — Inlet Guide Vanes IGVM — Inlet Guide Vanes Motor

NOTES:

1. Connect TRAN1 toH4for 460 v units. Connect toH3for 230 v units. If 208/230 v units are run with a 208 v power supply connect toH2.

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 supply 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 underlined number signiﬁes a normally closed contact. Plain numbers (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.

LAT — Leaving-Air Temperature LPS — Low-Pressure Switch MTR — Motor MV — Main Valve NC — Normally Closed NO — Normally Open OFC — Outdoor Fan Contactor OFM — Outdoor (Condenser) Fan Motor OMR — Outdoor Motor Relay PCB — Power Exhaust Circuit Breaker PEC — Power Exhaust Contactor PEDM — Power Exhaust Damper Motor PEM — Power Exhaust Motor P, PL — Plug RCB — Return Fan Circuit Breaker RES — Resistor RFC — Return Fan Contactror RFM — Return Fan Motor SCT — Saturated Condensing Thermistor TB — Terminal Block TRAN — Transformer U—Unloader VFD — Variable Frequence Drive

Field Wiring Factory Wiring

Fig. 55 — Typical Wiring Schematic; 48FK,JK and 50FK,FY,JK,JY Units (054-074 Shown)

Fig. 55 — Typical Wiring Schematic; 48FK,JK and 50FK,FY,JK,JY Units (054-074 Shown) (cont)

SERVICE TRAINING

Packaged Service Training programs are an excellent way to increase your knowledge of the equipment discussed in this manual, including:

• Unit Familiarization

• Installation Overview

A large selection of product, theory, and skills programs are available, using popular video-based formats 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

• Maintenance

• Operating Sequence

Manufacturer reserves the right to discontinue, or change at any time, speciﬁcations or designs without notice and without incurring obligations.

Book 1 1

Tab 1a 1b

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

START-UP CHECKLIST

MODEL NO.: DATE:

SERIAL NO.: TECHNICIAN:

I. PRE-START-UP:

M VERIFY THAT UNIT IS LEVEL M VERIFY THAT ALL PACKING MATERIALS HAVE BEEN REMOVED FROM UNIT M LOOSEN ALL SHIPPING HOLDDOWN BOLTS AND REMOVE SHIPPING BRACKETS PER INSTRUCTIONS M VERIFY THAT COMPRESSOR SUSPENSION SPRINGS HAVE BEEN LOOSENED PER INSTRUCTIONS M VERIFY OPENING OF ECONOMIZER HOODS M VERIFY INSTALLATION OF EXHAUST HOODS M CONFIRM THAT TUBING FOR SPACE AND SUPPLY DUCT PRESSURES HAS BEEN INSTALLED M VERIFY THAT CONDENSATE CONNECTION IS INSTALLED PER INSTRUCTIONS M VERIFY THAT POWER SUPPLY MATCHES UNIT DATA PLATE M VERIFY THAT ALL ELECTRICAL CONNECTIONS AND TERMINALS ARE TIGHT M CHECK GAS PIPING FOR LEAKS (48FK,JK ONLY) M CHECK THAT INDOOR-AIR FILTERS ARE CLEAN AND IN PLACE M CHECK FAN WHEEL AND PROPELLER FOR LOCATION IN HOUSING/ORIFICE, AND VERIFY SET SCREWS

ARE TIGHT

M VERIFY THAT FAN SHEAVES ARE ALIGNED AND BELTS ARE PROPERLY TENSIONED M OPEN SUCTION, DISCHARGE, AND LIQUID LINE SERVICE VALVES M CHECK COMPRESSOR OIL LEVEL SIGHT GLASS AND VERIFY PROPER LEVEL M VERIFY THAT CRANKCASE HEATERS HAVE BEEN ENERGIZED FOR 24 HOURS M CHECK VOLTAGE IMBALANCE

LINE-TO-LINE VOLTS: AB V AC V BC V (AB + AC + BC)/3 = AVERAGE VOLTAGE = V MAXIMUM DEVIATION FROM AVERAGE VOLTAGE = 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

M 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)

M SUPPLY AIR SET POINT (P1) SET BETWEEN 45 AND 70 F M ECONOMIZER MINIMUM POSITION (P5) SET PER PLANS M SUPPLY AIR SET POINT RESET SETTINGS:

RESET INITIATION TEMPERATURE (P7) (TYPICALLY 68 TO 72 F) RESET LIMIT TEMPERATURE (P3) (TYPICALLY 60 TO 70 F)

M MORNING WARM-UP TEMPERATURE (TYPICALLY 50 TO 65 F) M IGV/VFD DUCT PRESSURE SET POINT PER PLANS M BUILDING PRESSURE (MODULATING POWER EXHAUST) SET PER PLANS M 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%)

M 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

EXHAUST FAN AMPS

ELECTRIC HEAT AMPS L1 L2 L3

TEMPERATURES

OUTDOOR-AIR TEMPERATURE RETURN-AIR TEMPERATURE COOLING SUPPLY AIR

F DB (Dry-Bulb) FDB F WB (Wet-Bulb) F

PRESSURES

GAS INLET PRESSURE GAS MANIFOLD PRESSURE STAGE NO. 1 REFRIGERANT SUCTION CIRCUIT NO. 1 REFRIGERANT DISCHARGE CIRCUIT NO. 1

IN. WG

IN. WG STAGE NO. 2 IN. WG

PSIG CIRCUIT NO. 2 PSIG PSIG CIRCUIT NO. 2 PSIG

M VERIFY REFRIGERANT CHARGE USING CHARGING CHARTS IN UNIT INSTALLATION INSTRUCTIONS

GENERAL

M ECONOMIZER MINIMUM VENT SETTING TO JOB REQUIREMENTS

IV. NOTES

CUT ALONG DOTTED LINE CUT ALONG DOTTED LINE

Manufacturer reserves the right to discontinue, or change at any time, speciﬁcations or designs without notice and without incurring obligations.

Book 1 1

Tab 1a 1b

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

----------------------------------------------------------------------------------------

Carrier 48FK038, 48FK044, 48FK048, 48FK054, 48FK064 Controls Operation And Troubleshooting

Specifications and Main Features

Frequently Asked Questions

User Manual