Carrier 48JK048, 50FY034, 50FY048, 50JY034, 50JY048 Operating And Troubleshooting Manual

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Controls Operation,

and Troubleshooting

CONTENTS

Page

SAFETY CONSIDERATIONS GENERAL

Rooftop Information VAV Control System Processor Board

• 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 Thermistors

• T1 — SUPPLY-AIR TEMPERATURE THERMISTOR

• T2 — RETURN-AIR TEMPERATURE THERMISTOR

• T3 — SA TURATED CONDENSING TEMPERATURE, CIRCUIT 1

• T4 — SA TURATED 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) Economizer

• ENTHALPY CONTROL

• DIFFERENTIAL ENTHALPY

Supply Fan Variable Frequency Drive (VFD) High Capacity Modulating Power

Exhaust Variable Frequency Drive

Temperature Reset CONTROLS INSTALLATION

Control Wiring

• 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

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

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

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

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

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

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

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

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

. . . . . . . . . . . . . . . . . . . . . . 2

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

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

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

. . . . . 12

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

. . . . . . . . . . . . . . . . . . 13-25

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

48FK,JK034-104

48FM078-104

50FK,FY,JK,JY034-104

50FM,FS078-104

Variable-Air Volume Rooftop Units

Page

Control From Remote Building Management

System (BMS)

• OCCUPIED/UNOCCUPIED

• NIGHT SETBACK CONTROL

• UNIT SUPPLY AIR SET POINT ADJUSTMENT

• DEMAND UNIT (1-STAGE OR 2-STAGE)

• SUPPL Y DUCT PR ESSURE SET PO INT ADJUS TMENT

• EXTERNAL ALARM SIGNAL

• REMOTE ECONOMIZER CONTROL

Smoke Control Modes

• FIRE SHUTDOWN MODE

• PRESSURIZATION MODE

• EVACUATION MODE

• SMOKE PURGE MODE

• INSTALLATION

• CONFIGURATION

• OPERATI NG SEQUENCE

Air Pressure Tubing

• INLET GUIDE VANES

• SUPPLY FAN VARIABLE FREQUENCY DRIVE

• MODULATING POWER EXHAUST

START-UP Initial Check Configuration Header DIP Switches Adjusting Set Points Potentiometers Supply Fan Control with IGV Option Supply Fan Control with VFD Option Modulating Power Exhaust Option or

Accessory) (48FK,JK and 50FK,JK Units)

High Capacity Power Exhaust

(48FM and 50FM,FS Units)

START UNIT Quick Test Program

OPERATING INFORMATION Digital Display

• CODES 0 THROUGH 8, CAPACITY STEPS

• CODES 20 THROUGH 30 AND 88, OPERATIONAL STATUS

• CODES 51 THROUGH 87, DIAGNOSTIC INFORMATION

Operating Sequence

• SIZE 034, 038 AND 048-088 UNITS

• SI ZE 044 UNITS

• SI ZE 104 UNITS

Head Pressure Control Supply Fan Control with IGV Supply Fan Control with VFD Modulating Power Exhaust (48FK,JK and

50FK,JK Units Option or Accessory)

High Capacity Modulating Power Exhaust

(48FM and 50FM,FS Units)

Unit Staging

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

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

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

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25-31

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

. . . . . . . . . . . . . . . . . . . . . . . . . . . 26

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

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. . . . . 30

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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31-34

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

. . . . . . . . . . . . . . . . . . 34-44

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

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

. . . . . . . . . . . . . . . . . . . . 38

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. . . . . . . . . . . . . . . . . . . . 38

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

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. 534-763 Printed in U.S.A. Form 48/50F,J-3T Pg 1 3-00 Replaces: 48/50F,J-1T

CONTENTS (cont)

Page

TROUBLESHOOTING Checking Display Codes Complete Unit Stoppage Single Circuit Stoppage Restart Procedure Diagnostic Codes

• CODES 51, 52, 55, 56: COMPRESSOR FAILURE

• 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: SUPPL Y-AIR TEMPER ATURE 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

• 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 Supply Fan Variable Frequency Drive

• STANDARD TRANSDUCER CONTROL

• EXTERNAL SIGNAL CONTROL

• SUPPLY FAN MOTOR OVERLOAD PROTECTION

•VFD OPERATION

• VFD OPERATIONAL STATUS

• RESTORING FACTORY VFD DEFAULTS

Power Exhaust Variable Frequency Drive

• STANDARD TRANSDUCER CONTROL

• EXTERNAL SIGNAL CONTROL

• POWER EXHAUST FAN MOTOR NO. 1 OVERLOAD PROTECTION

• POWER EXHAUST VFD OPERATION

• POWER EXHAUST VFD OPERATIONAL STATUS

• RESTORING FACTORY POWER EXHUAST VFD DEFAULTS

Unit Wiring START-UP CHECKLIST

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

. . . . . . . . . . . . . . . . . . . . . . . . . 44-60

. . . . . . . . . . . . . . . . . . . . . . . . 44

. . . . . . . . . . . . . . . . . . . . . . . . . 44

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

. . . . . . . . . . . . . . . . . . . . . 48

. . . . . . . . . . . . . . . . . . . 48

. . . . . . . . . . . . . . . . . . . . . . 52

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

. . . . . . . . . . . 52

. . . . . . . 55

. . . . . . . . . . . . . . . . . . CL-1, CL-2

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 comp lete d.

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.

GENERAL

IMPORTANT: This literature contains controls, operation, and troubleshooting data for 48FK,FM,JK and 50FK,FM,FS,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,FM,JK and 50FK,FM,FS,FY,JK,JY units provide ventilation, cooling, and heating (when equipped) in Variable Air Volume (V AV) applications. These units contain factory-installed controls which provide full system management. The unit controls also perform self diagnostic tests at unit startup, 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 —

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 WILL NOT START until this is

accomplished. See base unit installation instructions lit-

erature for details.

VAV Control System —

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

The VA V 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-insta lled acc esso ries.

The rooftop controls cycle

The 30 to 100-ton VAV roof-

The VAV control system monitors and controls the follow-

ing 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)

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 t o the proc essor board through wire and ribbon cables.

Several temperature inputs are connected to the processor. There are either 4 or 5 thermistors (depending on the fieldinstalled 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 T able 2.

In addition to the unit status switch inputs, the processor board also accepts inputs from several potentiometers. These potentiometers control various operational characteristics of the system. Inputs are received by the processor through pin terminal connector J3. See Fig. 4.

Table 1 — Pin Terminal Connector J1

Thermistor Inputs

CONNECTOR J1

TERMINAL NO.

1,2

14,15

16,17

18,19 20,21

LEGEND

Thermistor

T —

*If equipped with accessory temperature reset package. NOTE: Terminal numbers 3-13 are not used on these units.

TEMPERATURE

INPUT

Reset Temperature* T10 Saturated Condensing

Temp., Circuit 2 Saturated Condensing

Temp., Circuit 1 Return-Air Temperature T2 Supply-Air Temperature T1

UNIT SIZE

034-104

LEGEND

DIP — EPPOM — EXV —

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

Dual In-Line Package Erasable, Programmable Read-Only Memory Electronic Expansion Valve

*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.

Fig. 1 — Processor Board

LEGEND

T—

Thermistor Field Wiring Accessory

Fig. 2 — Pin Terminal Connector J1

Thermistor Inputs

LEGEND

CR — EC — LPS —

Control Relay Enthalpy Control 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 — EC — LPS —

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

Control Relay Enthalpy Control Low-Pressure Switch

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

UNIT SIZE

034-104

Jumpered

LPS2

LPS1

CR2

CR1

LEGEND

IN — P— RNT — SW —

Input Factory Wiring Potentiometer Field Wiring Return Accessory Switch

Fig. 4 — Pin Terminal Connector J3

Potentiometer Inputs

All of the potentiometers must be set before the unit is started in order for the unit to function prope rly. See Start Up, Potentiometers section on page 27 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 be en programmed to accept an operational range for the potentiometer, which may not be the same as the valid range.

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 — Economiz er feedback potentiometer is located on the economizer motor. The microprocessor is programmed to indicate an alarm if the travel during initializatio n is less than 10% of the tota l 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 potentiomet er 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 Wa rm-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 w hich 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 HEADER AND DIP SWITCH ASSEMBLY — 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 field-installed 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 —

and 115-v loads. See Fig. 5. The relay board is connected to the processor board by a ribbon cable at pin J9. Electrical conne ctions 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 —

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 —

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 supply-air te mperature.

T2 — RETURN-AIR TEMPERATURE THERMISTOR — This thermistor is located in the mixed-air portion of the unit cabinet. The thermistor ’s primary function is to provide 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 — SATURATED CONDENSING TEMPERATURE, 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 — SATURATED CONDENSING TEMPERATURE, 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 TEMPERATU RE — 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.

The relay board is used to control 24-v

The display board is located in the

The processor uses up to 5 thermistors to

Table 3 — Output Pin and Terminal Assignments

OUTPUT PIN-

TERMINAL

J6-1

J6-2

J6-3

J6-4

J6-5

J6-6

J6-7 J6-8 J5-1 J5-2

J5-3

J5-4

J5-5

LEGEND *Circuit 1.

ALM — CR — ECR — EOR — HIR — IFC — OFC — U—

Alarm Control Relay Economizer Close Relay Economizer Open Relay Heat Interlock Relay Indoor (Evaporator) Fan Contactor Outdoor (Condenser) Fan Contactor Unloader

NAME RATING DEVICE

Stage 1 Compressor Relay (K1)*

Stage 2 Compressor Relay (K2)*

Stage 3 Compressor Relay (K3)*

Compressor Relay (K4)† Not Used Stage 5

Compressor Relay (K5)† Stage 6

Compressor Relay (K6)† Economizer Open Relay (K7) EOR Economizer Close Relay (K8) ECR Supply Fan Relay (K9) Morning Warm-Up Relay (K10) HIR Stage 1 Condenser

Fan Relay (K11) Stage 2 Condenser

Fan Relay (K12) External Alarm Relay (K13) ALM

†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.

24 vac

115 vac

CR1

U2**

CR2

Not Used

IFC

OFC2/OFC3††

OFC4||

LEGEND

Control Relay

CR —

Terminal Pin Connectors

J—

Relay

K—

Fig. 5 — Relay Board

P1 SUPPLY AIR SET POINT POTENTIMETER

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 s tatuses and to sta rt 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 re lay 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 —

(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.

The accessory board is standard

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 demand limit provid es a means to li mit the capaci ty of the VAV unit using an external switch. Single step demand limit will limit the compressor displacement based on the ratio of the wiper arm to the full scale resistance. The exact percentage of capacity reduction differs depending on the number of capacity steps.

A 3-wire, 5 to 20 Kohm, field-supplied potentiometer (P4) is required for this option. The potentiometer should be wired to the processor J3 connections. In order to control the demand limit, the wiper arm of the potentiometer should be switched open and closed based on the demand limit requi rement. 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 ar m 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.

T wo 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

(48FK,JK ONLY)

HORIZONTAL SUPPLY SECTION

(50FY,JY ONLY) AND EXTENDED

PLENUM SECTION (50FKX,FKY,JKX,JKY)

Fig. 7 — Thermistor T1 Location, 48FK,JK, 50FY,JY and 50FKX,FKY,JKX,JKY 034-048 Units

FAN DISCHARGE/ELECTRIC HEAT SECTION

Fig. 8 — Thermistor T1 Location, 50FK,JK034-048 Units

GAS SECTION

(48FK,FM,JK)

HORIZONTAL SUPPLY SECTION (50FS,FY,JY)

AND EXTENDED

PLENUM SECTION (50FKX,FKY,FMX,FMY,JKX,JKY)

Fig. 9 — Thermistor T1 Location, 48FK,FM,JK, 50JY and

50JKX,JKY 054-074 Units and 50FKX,FKY,FMX,FMY and 50FS,FY054-104 Units

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

FAN DISCHARGE/ELECTRIC HEAT SECTION

STANDARD

Fig. 13 — Thermistor T3 and T4 Locations,

Size 034-048 Units

FILTERS

BAG

FILTERS

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

STANDARD FILTERS AND

PLEATED FILTERS

BAG FILTERS

(054-074 Only)

Fig. 12 — Thermistor T2 Location, Size 034-048 Units

ENTHALPY CONTROL 48FK,JK and 50FK,FY,JK,JY Units

— 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 removi ng the upper hood filter. See Fig. 17.

48FM and 50FM,FS Units

— The control is locat ed on the metal upright between the two economizer hoods, on the right hand side of the unit, and can be accessed by removing the filter on either economizer hood.

DIFFERENTIAL ENTHALPY — Added efficiencies in 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 t he re turn -air duc t.

Economizer —

Economizer control is used to control the outside and return air dampers of the unit, to satisfy space cooling demand using all outside air (when permitted), and to satisfy cooling in conjunction with compressor operation (when conditions permit). During Occupied periods without cooling demand, the outside-air dampers will be at the user-configured Minimum Damper Position (at P5 on accessory board). During Unoccupied periods, the outside-air dampers will be closed.

The economizer is a standard feature on 48FM and 50FM,FS units and is available as a factory-installed option on 48FK,JK and 50FK,FY,JK,JY units.

The user can install an ac cessory differential enth alpy sensor to enhance economizer control. Refer to the installation section for field wiring of the sensor.

054 UNITS

064, 074, 078 UNITS

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

088, 104 UNITS

LEGEND

Fig. 18 — Variable Frequency Drive,

Sizes 034-048 and 078-104

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

ECON — MIN — P— VAV —

Economizer Minimum Potentiometer Variable-Air Volume

Fig. 15 — Accessory Relay Board

(Standard; Factory Supplied)

The unit is supplied with a pressure transducer capable of measuring from 0.0 to 5.0 in. wg. The pressure transducer wi ll send a 4 to 20 mA signal to the VFD to modulate the speed of the indoor fan motor to precisely control the fan to the desi red 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.

High Capacity Modulating Power Exhaust Variable Frequency Drive (48FM and 50FM,FS Units Only) —

to modulate the power exhaust fan motor no. 1 and stage the power exhaust fan motor no. 2 in order to maintain building static pressure. The PE VFD is loc ated at the re turn air end of the unit of the opposite side from the auxiliary control box and can be accessed by opening the access door.

The unit is supplied with a pressure transducer capable of measuring from –0.5 to +0.5 in. wg. The pressure transducer will send a 4 to 20 mA signal to the PE VFD to modulate the speed of the power exhaust motor no. 1 and also stage on/off the power exhaust motor no. 2 to precisely maintain the desired building pressure set point. The PE VFD is factory set at 0 in. wg. Refer to Operating Sequence section for more information on the PE VFD.

The PE VFD has been programmed and wired at the factory for this application. No further adjustments (except for Building Pressure Set Point) should be necessary at start-up. Factory jumper wire configurations are shown in the Power Exhaust Variable Frequency Drive sec tion in the Troubleshooting section on page 55.

The power exhaust VFD (PE VFD) is used

LEGEND

IC — IN — P— RTN —

Integrated Circuit Input Potentiometer Return

Fig. 16 — Two-Step Demand Limit Module

Fig. 17 — Enthalpy Sensor Location

(48FK,JK and 50FK,FY,JK,JY Units Only)

Supply Fan Variable Frequency Drive (VFD) —

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 optional VFD is used to modulate supply fan

A separate service manual for the factory installed PE VFD is supplied with each unit. Refer to PE VFD manual for more information on the PE VFD.

Temperature Reset —

Accessory temperature reset allows the unit to automatically adjust (‘‘reset ’’) the supply-air temperature set point to a higher value once most of the space cooling load has been met. When the space conditions are sat isfied, the VAV terminals will close to the minimum position. All VAV units will sense the decrease in actual supply-air temperature and the unit controls respond by reducing capacity stages to m ai nta in user-established supp ly - a ir set point temperature. When VAV units are also equipped with optional supply duct pressure controls (either inlet guide vanes [IGV] or variable frequency drive package), the unit also senses an increase in duct static pressure and responds by closing IGV dampers or slowing fan wheel speed to maintain user-configured set points for supply duct pressure. Allowing the supply-air temperature to be reset to a higher value maintains air c irculation 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 21 . 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 Te mperature 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 VA V units are:

• smoke cont rol modes

• differential enthalpy sensor

• electric heaters (sizes 034-074 only)

• modulating power exhaust

• Motormaster

• 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 —

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 (siz es 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 wit h 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

I control

A switch or timeclock (field supplied)

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 termina ls 3 and 4 (for normally open contacts) and terminals 3 and 7 (for normally closed contacts) on terminal block 3 (sizes 034-048) or terminal block 4 (sizes 054-104). See Fig. 24. Note that a fieldsupplied 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.)

SP AC E TEMPERATURE RESET AC CESSORY (50DJ900021) — Consists of a thermistor (T10) and a rese t board with a potentiometer (P7) that is used to set space temperature at which reset starts. Mount reset boar d in unit control box or ot her 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 nece ssary t o splice additional wire to thermistor. The reset board has 2 pressur e connectors for field wiri ng. (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 at which reset function will start). Maximum of 80 F, minimum 0° F. Set bel ow normal room cooling set point level to sense overcooling in the occupied space.

NOTE: It is difficul t to accura tely set t he P7 potenti ometer 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:

= the desired set point of the P7 potentiometer in ohms

T10

= the resistance of the T10 thermistor for the desired

— Reset temperature set point (temperature

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

OCCUPIED/UNOCCUPIED

SWITCH

NIGHT SETBACK THERMOSTAT

NOTES:

1. Occ/Unocc switch closes when occupied.

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

034-048: TB3 054-104: TB4

Fig. 23 — Occupied/Unoccupied Switch with

Night Setback Thermostat

OPERATING SEQUENCE — If space temperature is above reset set point (T10 > P7), no reset will occur.

If space temperature is equal to or less that reset set point (T10 < P7), the LED will display 20 and reset will begin.

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 SP = Supply-Air Set Point P3 = Maximum Supply-Air Temperature (reset limit) P7 = Reset Initiation Temperature (reset set point) T10 = Actual Space Temperature 3 = Ratio for reset (F) (fixed parameter)

Table 4 — Thermistor Resistance and Voltage

Drop Characteristics

034-048: TB3 054-104: TB4

FIELD

N.O.

N.C.

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 Tabl e 4 for 70 F is 5929 ohms.

T10

= 13,084 – 5929

= 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 po int (max imu m tem per ature 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).

TEMP

(F)

31.0

32.0

33.0

34.0

35.0

36.0

37.0

38.0

39.0

40.0

41.0

42.0

43.0

44.0

45.0

46.0

47.0

48.0

49.0

50.0

51.0

52.0

53.0

54.0

55.0

56.0

57.0

58.0

59.0

60.0

61.0

62.0

63.0

64.0

65.0

66.0

67.0

68.0

69.0

70.0

71.0

72.0

73.0

74.0

75.0

76.0

77.0

78.0

79.0

80.0

RESISTANCE

(Ohms)

16813.8 3.582

16345.7 3.553

15892.2 3.523

15452.7 3.494

15026.7 3.464

14613.9 3.434

14213.6 3.404

13825.5 3.373

13449.2 3.343

13084.2 3.312

12730.1 3.281

12386.6 3.250

12053.3 3.219

11730.0 3.187

11416.1 3.156

11111.5 3.124

10815.8 3.093

10528.7 3.061

10250.0 3.029

9979.3 2.997

9716.5 2.965

9461.3 2.933

9213.4 2.901

8972.6 2.869

8738.6 2.837

8511.4 2.805

8290.6 2.772

8076.1 2.740

7867.7 2.708

7665.1 2.676

7468.3 2.644

7277.1 2.612

7091.2 2.581

6910.6 2.549

6735.1 2.517

6564.4 2.486

6398.6 2.454

6237.5 2.423

6080.8 2.391

5928.6 2.360

5780.6 2.329

5636.8 2.299

5497.0 2.268

5361.2 2.237

5229.1 2.207

5100.8 2.177

4976.0 2.147

4854.8 2.117

4736.9 2.088

4622.4 2.058

VOLTAGE

DROP (v)

SIZES 034-048

TB3

TO ACCESSORY SPACE TEMPERATURE RESET CONTROL BOARD

SIZES 054-104

TB4

SIZES 034-048 TB3

TO ACCESSORY SPACE

TEMPERATURE RESET

CONTROL BOARD

SIZES 054-104 TB4

RED

BLK

RED BLK

RED

BLK

RED

BLK

SENSOR 1 SENSOR 2 SENSOR 3 SENSOR 4

RED

BLK

RED

BLK

SPACE TEMPERATURE RESET — 4 SENSOR AVERAGING APPLICATION

RED

BLK

SENSOR 1

RED

BLK

SENSOR 2

RED BLK

SENSOR 3

RED

BLK

SENSOR 4

BLK

RED

NOTE: Sensor part number is HH79NZ014.

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-STEP DEMAND LIMIT — This function wi ll limit

the total compressor staging based on the ratio of the set point potentiomete r’s wiper arm posit ion to the full sca le resistanc e 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 22 . 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). Loca te the potentiometer (desi gnated 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

034-048: TB3 054-104: TB4

5-20K POTENTIOMETER (P4)

SWITCH

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.

3. is field wiring.

Fig. 29 — 115-Volt Field Wiring to Accessory

2-Step Demand Limit Control Module

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 ena ble 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 control 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 ena ble 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 Te st procedures.

CONFIGURATION Single-Step Demand Limit

— Field-installed potentiometer 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 differs depending 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 22 . If a potentiometer setting or input is out of range, the control will terminate the demand limit function and show code 84 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.

Control From Remote Building Management System (BMS) —

municating control system, and it cannot be acce ssed 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 com-

OCCUPIED/UNOCCUPIED — The unit control system will initiate normal occupied mode functions (including Morning W arm-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 spac e temperatures have returned to unoccupied set point levels, and the unit will shut down normally.

The contact closure from the BMS must be an isolated contact set, normally open, suitable for 24 volts AC pilot duty.

NOTE: If the rooftop unit is equipped with a VFD and night setback cooling operation is intended, the fan system must be controlled to pe rmit FULL SUPPLY FAN AIR DELIVERY during 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 resi stance transducer with a 4 to 20 mA or 2 to 10 vdc signal generated by the BMS.

This emulation requires the following field-supplied parts:

• Variable resistance transducer (Kele RES-1 or equiva-

lent, 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) 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

— Connect fixed resistance

Configuration

1. Set DIP switch no. 2 to ON.

2. Adjust manual potentiometer to 12.6 to 12.8 k-ohm.

3. Configure transducer for job site input signal from BMS.

4. Adjust Potentiometer (P3) on the rooftop to MAXIMUM SASP value (typically 65 to 70 F). The maximum P3 SASP

control limit is 70 F. Operation

SASP upward) when the sum of the resistance (fixed resistance + potentiometer + transducer) exceeds 13.1 k-ohm. Once reset is initiated, full range of reset (P3 setting minus configured SASP) will be reached with 500-ohm increase in transducer resistance (TR).

During Reset mode operation, Code 21 will appear on unit

display board. Formula: MSP = SASP +

(P3 — SASP)

[

MSP: Modified SASP (S ASP 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.

For Single-Step Demand Limit, emulate function of switch

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.

For 2-Step Demand Limit, install the accessory Demand

Limit Control Module (DLCM) according the instructions on page 18. Replace switch functions Switch 1 and Switch 2 with contact closures controlled by the BMS (see Fig. 29).

Follow unit control configuration instructions in the De-

mand Limit section on page 18. 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

the factory-installed VFD receives a 4 to 20 mA signal from the Duct Pressure (DP) transducer which indicates current supply duct pressure. The VFD then determines the 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 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).

— Configure as follows:

— Unit will initiate SASP Reset (adjust configured

(0.6 F)

(3) (100 ohm)

— Several accessory interface

X (TR — R@13.3)

— During normal unit operation,

]

034-048: TB3 054-104: TB4

TRANSDUCER

BMS

CONTROL

(4 TO 20 MA

2 TO 10 VDC

SIGNAL)

LEGEND

Fig. 30 — Remote SASP Wiring

P—

Manual Potentiometer

R—

Fixed Resistor Field Wiring

LEGEND

Fig. 31 — External Alarm Indication

R—

Fixed Resistor Factory Wiring Field Wiring

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 (com mon). This signal can be forwarded to the BMS by adding a signal relay at the alarm output, placing its coil across terminals TB24 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 diag-

nostic 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 aut omatic 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.

Smoke control mode Pressurization requires the economizer function. Evacuation and Smoke Purge modes require both economizer and power exhaust functions. Both functions are standard features on 48FM and 50FM,FS units. These functions require factory-installed options, field-installed accessories and/or field-supplied exhaust systems on 48FK,JK and 50FK,FY,JK,JY units. Consult price pages for specific details.

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. The economizer is required for this function. The economizer is standard on 48FM and 50FM,FS units. The economizer is a factoryinstalled option on 48FK,JK and 50FK,FY,JK,JY units. Pressurization is accomplished by:

• opening the economizer

TB2

LIGHT

RELAY

SIGNAL TO BMS

TB2

• running the supply fan (opt ional inlet guide vanes open or optional VFD [variable frequency drive] at normal duct static pressure set point)

• shutting off the power exhaust fans (Standard on 48FM and 50FM,FS units. Factory-installed option or fieldinstalled accessory on 48FK,JK and 50FK,JK units)

This allows the sp a ce to b e ove rp r e ssu rized relative to adjacent zones and prevents or slows entry of smoke into this space from adjacent zones.

EVACUATION MODE — Evacua tion mode removes smoke or undesirable air from interior spaces w ithout reintroducing unsuitable air. The economizer and power exhaust are required for this function. The economizer and power exhaust are standard on 48FM and 50FM,FS units. The economizer is a factory-installed option and the power exhaust is a factoryinstalled option or field-installed accessory on 48FK,JK and 50FK,JK units. Evacuation is accomplished by:

• turning supply fan off

• opening the economizer

• running the exhaust fans

• opening the exhaust dampers

SMOKE PURGE MODE — Smoke Purge mode removes smoke from the interior spaces and re places it with fresh outside air. The economizer and power exhaust are required for this function. The economizer and power exhaust are standard on 48FM and 50FM,FS units. The economi zer is a factoryinstalled option and the power exhaust is a factory-installed option or field-installed accessory on 48FK,JK and 50FK,JK units. Smoke purge is accomplished by:

• turning supply fan on

• opening the economizer

• running the exhaust fans

• opening the exhaust dampers INSTALLATION — To enable one or more of the possible

smoke control modes available with these units, de termine t he switches required for the desired mode(s) from Table 6, fieldsupply and install the appropriate switches and field wire pe r Fig. 32. Switch functions are shown in Table 7.

Table 5 — Smoke Control Modes

FUNCTION

Supply Fan IGV/VFD† Economizer Return Air

Damper Exhaust

Fans Exhaust

Damper

LEGEND

IGV — VAV — VFD —

*Power exhaust function required for this mode. †Applicable to VAV units with appropriate options.

Inlet Guide Vane Variable Air Volume Variable Frequency Drive

Fire

Shutdown

Off On Off On

— Open/On — Open/On

Closed Open Open Open

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 Ta ble 5), all unit operation (cooling, heating, supply fan and power exhaust) will terminate.

Pressurization

— At command from the field switches for

Pressurization mode (see T able 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

— At command from the field switches for Evacu-

ation mode (see Table 5):

1. Supply fan will turn off.

2. Economizer dampers will open.

3. Exhaust fans will run at maximum capacity.

4. Exhaust dampers will open.

Smoke Purge

— At command from the field switches for

Smoke Purge mode (see T able 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

*Not required on 48FM and 50FM,FS units (high capacity power exhaust units).

NOTE: All switches are shown in “as installed” (power OFF or deenergized) position. In these positions, none of these modes will be activated; normal unit operation is permitted by the base unit controls. To initiate any mode, all switches listed under this mode in the table must be energized, causing the depicted contact position to change from depicted positions to energized positions. Switches may be manually or electrically operated.

PRESSURIZATION

SW-9A/B SW-7

EVACUATION

(Modulating Power

Exhaust)

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

SW-8*

SMOKE PURGE

Table 7 — Switch Functions

SWITCH

NUMBER

SW-1 SW-2 SW-3 SW-4 SW-5 SW-6

SW-7

SW-8*

SW-9A/B

*Not required on 48FM and 50FM,FS units (units with high capacity power exhaust).

LEGEND

BP — DPS — EOR — HIR — IFC — IGV — N.C. — N.O. — PEC — PED — OFC — VFD —

Building Pressure Differential Pressure Switch Economizer Open Relay Heat Interlock Relay Indoor Fan Contactor Inlet Guide Vane Normally Closed Normally Open Power Exhaust Contactor Power Exhaust Damper Outdoor Fan Contactor Variable Frequency Drive

Air Pressure Tubing —

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 fire-retardant 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 co n trol de vi ce loc ati on in the uni t.

CONFIGURATION VOLTAGE FUNCTION

N.C. 115 Deenergize 115-v (OFC, Comp, IFC, Electric Heaters) N.C. 115 Deenergize TRAN7 (Process Board) N.O. 24 Energize EOR (Open Economizer Outside Air Dampers) N.O. 115 Energize IFC and CR-3 (IGV/VFD) N.C. 115 Isolate IFC and PEC for Separate Operation N.O. 115 Energize PEC (Power Exhaust)

N.O. 24

N.C. 24 Block Auto-Close at DPS (Due to Low BP)

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

115 max Signal Room Terminals to Open (HIR1)

Before options such as inlet

Open PED at DPS (48FK,JK and 50FK,JK Units) Force Power Exhaust VFD to Maximum Speed (48FM and 50FM,FS Units)

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

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

location where a constant duct pressure is desired.

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

Table 8 — Tubing Size

OPTION UNITS

Inlet Guide Vanes (IGV)

Supply Fan Variable

Frequency Drive (VFD)

Modulating Power Exhaust

ALL

FK,FKX,JK,JKX

FM,FS

NOMINAL TUBE

SIZE (in.)

SUPPLY FAN VARIABLE FREQUENCY DRIVE — The tubing for the duct pressure (DP) control option should sample supply duct pressure about the main trunk duct, at a location where a constant duc t pressure is desired.

The duct pressure is sensed by a pressure transducer. The pressure transducer output is directed to the VFD. On 034-048 units the DP transducer is located in the auxiliary c ontrol box. On 054-104 units, the DP transducer is located in the supply fan section. See Fig. 34. Use a nominal

/8-in. plastic tubing.

/3 of the way out from the unit in

/4-in. plastic tubing.

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

TB2TB2 SW-2

TB2

TB2TB2 SW-5

TB3

REMOVE JUMPER

TB2TB2 SW-2

TB4

TB2

TB2 SW-6

TB4

SW-3 TB4

SW-4

SW-9A

REMOVE JUMPER

TB2

TB2TB2 SW-5

TB2

TB4

TB3

REMOVED FROM TB3-7

LEGEND

DPS — HIR — PEVFD — SW — TB —

Differential Pressure Switch Heat Interlock Relay Power Exhaust Variable Frequency Drive Switch Terminal Block

HIR

WHT

REMOVED FROM C-DPS

SW-9B

TB3

48FK, JK AND 50FK, JK034-104 UNITS

SW-7

SW-8

GRA

48FM, AND 50FM, FS034-104 UNITS

PEVFD

SW7

Fig. 32 — Smoke Control Wiring

DPS

TB4

HIR

REMOVED FROM TB4-7

VIO

PEVFD

SW-9B

TB4

Fig. 33 — Modulating Power Exhaust and Inlet

Guide Vane Differential Pressure Switch

(Sizes 034-048)

MODULATING POWER EXHAUST 48FK,JK and 50FK, JK Units

— The tubing for the building pressure control (achieved via the Modulating Power Exhaust option/accessory) 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 nominal

/8-in. plastic tubing.

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

48FM and 50FM,FS Units

— The tubing for the building pressure control (achieved through the High Capacity Modulating Power Exhaust) should sample the building pressure in the area near the entrance lobby (or other appropriate and sensitive location) so that the location is controlled as closely to design pressures as possible.

A building pressure transducer (BPT) is used to sense the building pressure and supply a 4 to 20 mA signal to the power exhaust VFD (PE VFD) which controls the speed of exhaust fan motor no. 1 and stages on/off power exhaust fan motor no. 2 to maintain the building pressure. The BPT is located in the auxiliary control box. Use a nominal

/4-in. plastic tubing.

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

Fig. 34 — Inlet Guide Vane Differential

Pressure Switch and Variable Frequency Drive

(Sizes 054-104)

Fig. 35 — Modulating Power Exhaust Differential

Pressure Switch (Sizes 054-104)

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 t he Installa tion Instructions 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 properly attached, routed, and free from pinches or crimps that may affect proper control operation.

4. Set any control configurations that are required (fieldinstalled 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 Ta ble 9.

6. Check tightness of all electrical connections.

7. Perform quick test (see Quick Test Program section on page 31).

Table 9 — Potentiometer Inputs and Ranges

POTENTIOMETER DESCRIPTION LOCATION

CONTROL

VALID

RANGE

P2*

P4†

DLCM-P1 DLCM-P2

P5*

P7**

Supply Air

Set Point

Economizer

Position

Reset Limit

Demand Limit,

Single-Step

Demand Limit,

2-Step

Minimum Economizer

Position

Warm-Up

Set Point

Reset

Temperature

Display

Board

Economizer

Motor

Accessory

Board

45 to 70 F

0 to 100% None (0 if P2 is bad)

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

45 F if -22 F < P1 < 45 F 70 F if P1 > 70 F OR IF P1 < -22 F

Main Control Box 0 to 100% None

DLCM Board 50 to 100% None DLCM Board 0 to 49% None

Accessory Board 0 to 100% None

Accessory Board 40 to 80 F

40 F if 0° F < P6 < 40 F OR IF P6 < 95 F OR IF P6 < 0 80 F if 80 F < P6 < 95 F

Reset Board 40 to 100 F None

*Optional factory-installed economizer is required. Potentiometer P2 is not a set point.

†Accessory two-step demand limit module is required (which has 2 potentiometers), or a 5 to 20 k-ohm

field-supplied potentiometer is required for single-step demand limit.

**Accessory temperature reset is required.

NOTE: Potentiometers P1-P6 input data to pin terminal connector J3. Potentiometer P7 inputs data to pin terminal connector J1.

DEFAULT VALUE

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 m ay 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 2 ■ Off ■ Off ■ Off 3 ■ On/Off* ■ On/Off* ■ On/Off* 4 5 6 ■ Off ■ On ■ On 7 8 ■ Off ■ Off ■ Off

LEGEND

DIP — Dual, In-Line Package



— Broken Jumper (open circuit)

■ — Unbroken Jumper (closed circuit)

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

034-038,

048-088

Header

Position



 



Switch

Position

Off

On/Off*

Off

UNIT SIZE

Header

Position



 



044

Switch

Position

Off

On/Off* ■ On/Off*

Off

UNIT SIZE

Header

Position



104

Switch

Position

Off

Table 11 — Configuration Header Jumpers

JUMPER

NUMBER

1,2 Unit Type

3,4,5 Qty Compressors ■ 

6 Expansion Valve ■ TXV 7 Power Frequency 8 Not Used ■ No Significance

LEGEND

TXV — Thermostatic Expansion Valve VAV — Variable-Air Volume



— Broken Jumper (open circuit)

■ — Unbroken Jumper (closed circuit)

DIP Switches —

FUNCTION

The DIP switches c onfigure the unit for

FACTORY

SETTING



■ VAV Rooftop Unit



MEANING

2 Compressors

60 Hz

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 T able 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.

DIP SWITCH NO. 1 — Supply Air Set Point (SASP) Reset T ype. 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. For all 48FM and 50FM,FS units, this switch will be ON. Confirm setting per Tabl e 10. Change only if in error .

DIP SWITCH NO. 4 — Morning Warm-Up. For 48FK,FM,JK units, 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 sw itch will be OFF. If accessory electric heaters are installed (for 50FK,JK 034074 units 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 (single-step 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 set tings per Tabl e 12. Change only if in error .

Table 12 — DIP Switches

SWITCH

NO.

6,7 Unloaders

LEGEND

DIP — Dual, In-Line Package

*Control circuit breaker must be off before changing the setting of the DIP

switch.

†No economizer.

**And/or electric heat (50FK,JK034-074 units without plenum only).

FUNCTION

3 Economizer

8 Not Used Off No Significance

Reset

Mode

Reset Select

Morning

Warm-Up

Demand

Limit

Adjusting Set Points —

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

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).

Set points for high capacity modulating power exhaust (48FM and 50FM,FS units) are set at the power exha ust VFD keypad.

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 conside r 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 pote ntiometer, 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 tempe ratur e at which t he c ontrol wi ll ini tiate 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 13 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 capac ity stages can be used. When the wiper arm is closed, the capacity is reduced by t he 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 morni ng warmup sequence is terminated and VAV cool ing 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 condi tion will be signaled and a default value of 40 F will be used.

Supply Fan Control with IGV Option —

*The inlet guide vane differential pressure switch for the 034-048

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

Fig. 36 — Inlet Guide Vane Motor,

50FK,JK034-074 Units

*The inlet guide vane differential pressure switch for the 034-048

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

Fig. 37 — Inlet Guide Vane Motor, 48FK,JK, 50FJ,JY,

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

Fig. 38 — Inlet Guide Vane Motor,

Size 078-104 Units

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 al so has an adjustable null span. The null span is the pressure change t hat 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 posi-

tion (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 de crease span and counterclockwise to increase span. All swi tches leave factory with null span set at maximum position. The smaller the null span, the closer the pressure will be maintained to desired set point.

Supply Fan Control with VFD Option —

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 corre ct d ire ctio n.

The supply duct pressure transducer has a range of 0.0 to

5.0 in. wg. Its output is a 4 to 20 mA signal, scaled to this

range. The VFD translates this 4 to 20 mA input signal to represent a frequency value over the control range of 0 to 60 Hz. The factory default set point is 30 Hz, representing a supply duct pressure of 2.5 in. wg.

The inlet

The VFD

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.

CAPACITOR

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

NULL ADJUSTMENT

NULL DECREASE

SET POINT

DECREASE

SET POINT ADJUSTMENT

SET POINT INDICATOR

LEGEND

COM — N.C. — N.O. —

Common Normally Closed Normally Open

PLANE

Fig. 39 — Differential Pressure Switch for Inlet

Guide Vane and Static Pressure Control Option

and Modulating Power Exhaust Option

PERCENT

SECONDS

KW/AMPS/VOLTS

SETUP

PROGRAM

MONITOR

READ

WRITE

LOCAL/REMOTE

SPEED CTRL

RUN MODE

RUN

STOP

RESET

MANUAL/AUTO

COM

N.C.

N.O.

DISABLE SUPPLY FAN MOTOR — To disable the supply fan motor and change programming of VFD set point:

1. Turn off Indoor Fan Circuit Breaker (IFCB). This will remove power to the VFD.

Ensure the “CHARGE” lamp on the VFD is unlit. This may take up to 4 minutes. The “CHARGE” lamp indicates that the main capacitors in the VFD are charged. Internal components of the VFD should not be touched until the “CHARGE” lamp is completely out. Electrical shock can cause injury or death.

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 di scharged. 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 on page 30.

8. Once the program changes are completed, turn off IFCB.

9. Wait for the VFD display to go blank and remove VFD cover without touching any interior components.

10. Ensure that the charge indicator lamp is out which indicates that the VFD is di scharged. 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, Supply Fan Variable Frequency Drive section (page 52).

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 check-

ing default values.

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), corresponding to 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. Lo cate the pressure value in the table closest to the desired DPSP for this installation and use the corresponding VFD set point (Hz) value. If nec essary, interpolation between duct static pressure values is permissible.

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.

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

PRESSURE

(in. wg)

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

VFD SET POINT (Hz)

04.0

34.8

65.6

96.4 12 7.2 15 8.0 18 8.8 21 9.6

CONTROL SIGNAL

(mA)

PRESSURE

(in. wg)

2.00

2.25

2.50

2.75

3.00

3.25

3.50

VFD SET POINT

(Hz)

24 10.4 27 11.2 30 12.0 33 12.8 36 13.6 39 14.4 42 15.2

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

KEY OPERATION LED MESSAGE EXPLANATION

XX.X or OFF

↓

↓↑

READ

WRITE

*Choose set point from Table 13 according to desired duct pressure or Table 15 according to desired building pressure.

60.0 Pressing arrow key once will display the current frequency set point

45.0 (flashing) Pressing up/down arrow keys changes the desired set point

FC and 45.0 (flashing)

XX.X or OFF

Standard Monitor Mode (output frequency). If drive is disabled, display will read “OFF”. If enabled, display will show current output frequency

When the Read/Write key 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 “OFF”. If enabled, display will show current output frequency

CONTROL SIGNAL

(mA)

Modulating Power Exhaust (Option or Accessory) (48FK,JK and 50FK,JK Units) —

ulating Power Exhaust system will maintain 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 pressu re swi tch is loca te d in the auxi liary c ontrol box mounted in the corner next to the power exhaust motor door. T o 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 l abeled FILTER SECTION. See Fig. 35.

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 adjus table null span. The null spa n 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. w g 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 swi tches leave factory with null span s et at maximum position. The smaller the null span, the closer the pressure will be maintained to desired set point.

The Mod-

High Capacity Power Exhaust (48FM and 50FM,FS Units) —

late the power exhaust fan motor no. 1 speed and stage (on/off)

The power exhaust VFD will modu-

power exhaust fan motor no. 2 to maintain the building pressure. The set point for the building pressure control is set at the power exhaust VFD using the keyboard on the front of the power exhaust VFD enclosure. See Fig. 40.

NOTE: The VFD will always provide the proper phase sequences to the power exhaust fan motor.

The exhaust 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 exhaust fan operates in the correct direction, reverse any two leads on the main terminal block. All fans will then operates in the correct direction.

The building pressure transducer has a range of –0.5 to +0.5 in. wg. The output is a 4 to 20 mA signal, scaled to this range. The VFD translates the 4 to 20 mA signal to represent a frequency value over the control range of 0 to 60 Hz. See Ta ble 15. The set point for duct pressure control is established at the power exhaust VFD keypad in terms of Hz. The fact ory default set point is 30 Hz, representing a building pressure of

0.0 in. wg. DETERMINE POWER EXHAUST VFD SET POINT —

The unit of measure for the building pressure set point (BPSP) at the power exhaust VFD is output frequency (Hz), representing the desired BPSP (in. wg). To c onvert the desired BPSP into the power exhaust VFD set point, refer to T able 15. Locate the pressure value in the table closet t o the desired BPSP for the application and use the corresponding set point (Hz) value. If necessary, interpolation between duct static pressure values is permissible.

ADJUST PE VFD SET POINT — To adjust the PE VFD set point, the PE VFD must be powered. Since it is loc ated in the indoor section of the unit, use caution to ensure that the service access door is blocked open and will not close suddenly.

Change PE VFD set point according to Table 14.

Table 15 — PE VFD Set Point (Frequency

Command) for Building Pressure

PRESSURE

(in. wg)

0.50

0.45

0.40

0.35

0.30

0.25

0.20

0.15

0.10

0.05

VFD

SET POINT

(Hz)

12.0 7.20

15.0 8.00

18.0 8.80

21.0 9.60

24.0 10.40

27.0 11.20

CONTROL

SIGNAL

0.0 4.00

3.0 4.80

6.0 5.60

9.0 6.40

(mA)

PRESSURE

(in. wg)

0.00

–0.05

–0.10

–0.15

–0.20

–0.25

–0.30

–0.35

–0.40

–0.45

–0.50

VFD

SET POINT

(Hz)

30.0 12.00

33.0 12.80

36.0 13.60

39.0 14.40

42.0 15.20

45.0 16.00

48.0 16.80

51.0 17.60

54.0 18.40

57.0 19.20

60.0 20.00

CONTROL

SIGNAL

(mA)

START UNIT

T o start unit:

1. Close the unit-mounted ON/OFF switch (located i n 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 selfdiagnostic routine. When this is in effect, an 88 will appear in the display screen. Refer to Quick Te st Program section below, for instructions on completing the Quick T est program.

Quick Test Program —

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, a 20 will appear on the display . Immediately press dis play button once. An 88 will appear on the display and alarm light on

Turn on power to unit.

display board will be energized. This indicates that control system is ready to run quick test program.

IMPORTANT: Do not allow unit control circuit to remain energized with 20 showing on display for more than 2 minutes. If display button is not pressed within this time period, control will attempt to start unit.

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 but-

ton must be pressed at least once every 10 minutes for

control to remain in Quick Test mode. If button is not

pressed within th is tim e, contr ol wi ll attem pt to s tart t he

unit.

To recheck any step i n quick test program, cont rol 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 16-18.

1. Quick Test Steps 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 accordanc e 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 16.

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

In these steps, the microprocessor checks resistance values 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 19. Normal display code for good sensors and potentiometers is 1. A display code of 0 indicates a faulty potentiometer, thermistor or wiring. A 0 display also indicates that option is not being used.

Table 17 shows thermistor and set point potentiometer functions and quick test display codes.

Table 16 — Quick Test, Unit Configuration and Switch Check

QUICK

TEST

STEP NO.

1. 01 Type Unit — Air-Cooled VAV Configuration Header

2. 2 No. of Compressors Configuration Header

4. 60 60-Hertz Power Configuration Header

5. 0 or 1

6. 0 or 1

7. 0 or 1

8. 0 or 1

9. 0 or 1

1.0. 1 1 — Low-Pressure Switch Closed Low-Pressure Switch 1

1.1. 1 1 — Low-Pressure Switch Closed Low-Pressure Switch 2

1.2. 1 No Circuit 1 Oil Pressure Switch None*

1.3. 1 No Circuit 2 Oil Pressure Switch None*

LEGEND

DIP — EC — VAV —

*Units are not equipped with oil pressure switches.

Dual, In-Line Package Enthalpy Control Variable Air Volume

NORMAL DISPLAY

2 1

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

(044, 104)

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

1 — Demand Limit Used

0 — Enthalpy Switch Open 1 — Enthalpy Switch Closed

DESCRIPTION CONTROL SWITCH

DIP Switch No. 6 and 7

DIP Switch No. 2

DIP Switch No. 3

DIP Switch No. 4

DIP Switch No. 5

(Switch Off)

(Switch On)

Table 17 — Quick Test, Thermistor and Potentiometer Check

QUICK

TEST

STEP NO.

1.4. 1

1.5. 1

1.6. 1

1.7. 1

1.8. 1

1.9. 1

2.0. 1

2.1. 1

2.2. 1

2.3. 1

*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.

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)

Warm-Up Set Point Potentiometer (P6)

Table 18 — Quick Test, Output Relay Check

QUICK

TEST

STEP NO.

2.4. 1 1 — Open Economizer or Open Relay if no Economizer K7

2.5. 1 1 — Close Economizer or Close Relay if no Economizer K8

2.6. 1 1 — Energize Fan Relay and Heat Relay K9* and K10

2.7. 1 Energize Stage 1 Condenser Fan(s) K11

2.8. 1 Energize Stage 2 Condenser Fan(s) K12

2.9. 0 then 1 then 0 Energize Compressor 1† K1

3.0. 0 Energize Unloader 2; Not Used (044, 104) K2

3.1. 0 Energize Unloader 1 K3

3.2. 0 then 1 then 0 Energize Compressor 2† K5

3.3. 0 Not Used K6

LEGEND

Control Relay

CR —

*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

DESCRIPTION RELAY NUMBER

Table 19 — Sensor Resistance Values

TEMP

RESISTANCE

(F)

–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

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

(Ohms)

0 42,765 105 2,600 210 350 5 36,475 110 2,336 215 323

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 out-

put 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 18.

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

Digital Display —

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

CODES 0 THROUGH 8, CAPACITY STEPS — These codes indicate the number of cooling stages active at the time the display button is pressed. The highest code indicated on the display will be 6 for the 034,038 and 048-088 units, 4 for the 044 units, and 8 for the 104 units.

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 load if t he outdoor

The VAV control system uses a 2-digit

enthalpy is good. As long as the outdoor-air enthalpy is acceptable, no mechanical cooling will take place until the economizer dampers are fully open. The rest of the steps and the operational sequence vary due to the number of compressors and unloaders. Refer to Operating Sequence section on page 35 for the unit stages of operation.

CODES 20 THRO UGH 30 AND 88, OPERATIONAL STATUS — 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 20 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 T est mode.

T emp erature Res et

— If the unit is equipped with the accessory temperature reset package, and DIP swi tch 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 21 will appear in the display.

Demand Limit

— If the unit is equipped with the accessory demand limit control module or the field-supplied, single-step demand limit potentiometer, and DIP switch 5 is in the ON position, the uni t will limit the capacity stage s to a predetermined value. When this condition is in effect, a 22 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 26 will appear in the display .

Internal Failure

— If the unit detects an internal fault (such as a time measurement failure), or detects an inco rrect voltage on an input channel, a 30 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 self-diagnostic routine. When this is in effect, an 88 will appear in the display screen.

CODES 51 THROUGH 87, DIAGNOSTIC INFORMATION — 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 below 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 20 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 resist ance 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 26 will be displayed.

Unit heat will be energized through the heat interlock relay (HIR), and all of the occupied space a ir terminals will 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 morni ng 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 AV AILABLE 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 supply-air 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 cir cuit, the low-pressure switch will be bypassed for 120 seconds to prevent nuisanc e trips of the low -pressure swit ch. After startup, 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 e nergized. Compressor

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

/3 capacity. The crankcas e he at er fo r 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

/3 capacity.

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

loaded.

Stage 4 Relays K1, K 2, K3 , and K5 are ene rgized. Compres-

sor no. 1 is running at

/3 capacity, 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 e nergized. Compressor

no. 1 is running at

/3 capacity, and compressor no. 2

is running at full capacity.

Stage 6 Relays K1 and K 5 are energized. Both compressors

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 e nergized 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 O FM4 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 e nergized. Compressor no. 1

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

/2 capacity. 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. Compressor

no. 1 is running at

/2 capacity, 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 OF M1 and OFM3 are operating.

Stage 4 Rela ys K1 and K5 are energized. Both compressors

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 ene rgized 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

/3 capacity. 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 outdoor 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. Compressor

no. 1 runs at

/3 capacity and compressor no. 2 is running at full capacity. The crankcase heater for compressor no. 2 is deenergized. The first stage of condenser fans on circuit 2 has been energized. Fans OFM1, OFM2, OFM3, and OFM4 are operating.

Stage 4 Rela ys K1 and K5 are energized. Both compressors

no. 1 and no. 2 are running fully loaded.

Stage 5 Relays K1, K3 , K5, and K5 are energized. C ompres-

sor no. 1 runs at

/3 capacity 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 ene rgized. Compressors

no. 1, no. 2, and no. 4 are running fully loaded.

Stage 7 Rel ays K1, K2, K3, K5, and K6 are energized. Com-

pressor no. 1 runs at

/3 capacity 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 Rel ays K1, K2, K 5, and K6 are energized. Compres -

sors 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 m icroproces sor 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 mainta in 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, t he proce ssor will wa it one minute for the head pressures to stabilize before changing again, unless thermistor T3 or T4 senses a t emperature gre ater 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

LEGEND

OFM —

Outdoor (Condenser) Fan Motor

044 AND 048 UNITS

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 —

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.

For example, assume that set point on supply fan differe n-

tial 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 lowering duct pressure. Once set point pressure is reached, swit ch 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 —

with the VFD option, the supply fan static pressure is controlled by modulating the fan wheel speed. T he VFD operat es 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. T he 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 corre ct d ire ctio n.

In most VAV units,

When equipped

Modulating Power Exhaust (48FK,JK and 50FK,JK Units Option or Accessory) —

er exhaust assembly 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 differential pressure 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 50% of total exhaust capability, and fan no. 2 being staged On/Off (for a step of 50% of total exhaust capability) according to damper position on fan no. 1.

The pow-

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 posit ion is reduc ed to 10% of open position, PEDMS will open, deenergizing fan contactor PEC2 and shutting off fan no. 2.

High Capacity Modulating Power Exhaust (48FM and 50 FM,FS Units) —

modulating power exhaust assembly consists of two parallel and independent belt-drive large diameter forward curve fans. The fans, motors, and drives are located in a cabi net extension (not over the return air opening of the unit), in a plenum beneath the outside air intake plenum. The fa ns discharge horizontally out the back of the unit through individual barometric backdraft dampers with hoods. Operation is interlocked with economizer operation. Space pressure is monitored by a factory-installed differential pressure transducer. See Fig. 48 for component locations and sheet metal details.

The high-capacity modulating power exhaust is also available on horizontal 50FS units. Return duct opening is located on the left-hand side of the unit; exhaust air exits the unit out the back.

Control of the high-capacity modulating power exhaust system is accomplished via a combination modulated capacity fan/staged fan. Modulation is provided by a variable frequency drive controlling the direct output to fan no. 1 and controlling the ON/OFF status of fan no. 2.

Fan no. 1 is equipped with a Variable Frequency Drive, matched to the motor size. VFD output is determined by the VFD’s internal PID logic in response to actual space pressure as monitored by the Building Pressure (BP) transducer. Set point for BP control is established at the PE VFD. Available set point range is –0.50 to +0.50 in. wg. Building Pressure is sensed by a pick-up (field-supplied and -installed) located in the occupied space and connected to the BP transducer by

/4-in. tubing (field-supplied and -installed).

As the economizer actuator opens past 17% open, auxiliary PEC1. Fan motor no. 1 starts and runs.

Capacity of fan no. 1 is controlled by the output level from the BP VFD. As building pressure increases above set point, the VFD logic will increase the output level to fan no. 1 until set point is reachieved.

When space demand moves PE VFD output to 100% (60 Hz), VFD internal relay closes, energizing fan cont actor PEC2. Fan motor no. 2 starts and runs. Increased exhaust airflow will lower space pressure, causing PE VFD to reduce its output to fan no. 1 until set point is reachieved.

If space pressure decreases until PE VFD output is reduced to 25% of maximum output (15 Hz), VFD internal relay will open, deenergizing fan contactor PEC2 and shutting off fan no. 2.

Unit Staging —

quences are shown in Table 20.

Compressor loading and unloading se-

The high-capacity

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

Fig. 45 — Modulating Power Exhaust Component Locations; Sizes 054-104 (48FK, 50FK,JK Shown)

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

PE VFD

AUXILIARY CONTROL BOX

LARGE ECONOMIZER HOOD LOCATION

ACCESS DOOR

EXHAUST AIR

SMALL ECONOMIZER HOOD LOCATION

POWER EXHAUST ACCESS DOOR

Fig. 48 — Modulating Power Exhaust Return End Sheet Metal Skin Detail; 48FM and 50FM,FS Units

Table 20 — Compressor Loading and Unloading Sequences

SIZE 034 UNITS

COOLING

STAGE

0 1 2 3 4 5 6

Comp 1

OFF OFF OFF OFF 0 0

ON ON ON OFF 2 17 ON ON OFF OFF 4 33 ON OFF OFF OFF 6 50 ON ON ON ON 8 67 ON ON OFF ON 10 83 ON OFF OFF ON 12 100

Lead Circuit Lag Circuit

Unloader

Comp 2

Active

Cylinders

Percent

Capacity

COOLING

STAGE

0 1 2 3 4 5 6

Comp 1

OFF OFF OFF OFF 0 0

ON ON ON OFF 2 14 ON ON OFF OFF 4 28 ON OFF OFF OFF 6 42 ON ON ON ON 6 72 ON ON OFF ON 8 86 ON OFF OFF ON 10 100

Lead Circuit Lag Circuit

Unloader

SIZE 038 UNITS

Comp 2

Active

Cylinders

Percent

Capacity

COOLING

STAGE

0 1 2 3 4

COOLING

STAGE

0 1 2 3 4 5 6

COOLING

STAGE

0 1 2 3 4 5

Table 20 — Compressor Loading and Unloading Sequences (cont)

SIZE 044 UNITS

Lead Circuit Lag Circuit

Unloader

Comp 2

SIZE 048 UNITS

Comp 2

SIZE 054 UNITS

Comp 2

Comp 1

OFF OFF OFF 0 0

ON ON OFF 2 25 ON OFF OFF 4 50 ON ON ON 6 75 ON OFF ON 8 100

Lead Circuit Lag Circuit

Comp 1

OFF OFF OFF OFF 0 0

ON ON ON OFF 2 19 ON ON OFF OFF 4 38 ON OFF OFF OFF 6 58 ON ON ON ON 6 62 ON ON OFF ON 8 81 ON OFF OFF ON 10 100

Lead Circuit Lag Circuit

Comp 1

OFF OFF OFF OFF 0 0

ON ON ON OFF 2 20 ON ON OFF OFF 4 40 ON OFF OFF OFF 6 60 ON ON OFF ON 10 80 ON OFF OFF ON 12 100

Active

Cylinders

Active

Cylinders

Active

Cylinders

Percent

Capacity

Percent

COOLING

STAGE

0 1 2 3 4 5 6

COOLING

STAGE

0 1 2 3 4 5 6

SIZE 064 UNITS

Lead Circuit Lag Circuit

Comp 1

OFF OFF OFF OFF 0 0

ON ON ON OFF 2 17 ON ON OFF OFF 4 33 ON OFF OFF OFF 6 50 ON ON ON ON 8 67 ON ON OFF ON 10 83 ON OFF OFF ON 12 100

Comp 1

OFF OFF OFF OFF 0 0

ON ON ON OFF 2 14 ON ON OFF OFF 4 29 ON OFF OFF OFF 6 43 ON ON ON ON 8 71 ON ON OFF ON 10 86 ON OFF OFF ON 12 100

Unloader

Lead Circuit Lag Circuit

Unloader

SIZE 074, 078 UNITS

Unloader

Comp 2

Active

Cylinders

Active

Cylinders

Capacity

Percent

COOLING

STAGE

0 1 2 3 4 5 6

COOLING

STAGE

0 1 2 3 4 5 6 7 8

Table 20 — Compressor Loading and Unloading Sequences (cont)

SIZE 088 UNITS

Lead Circuit Lag Circuit

Comp 1

OFF OFF OFF OFF 0 0

ON ON ON OFF 2 16 ON ON OFF OFF 4 33 ON OFF OFF OFF 6 50 ON ON ON ON 8 66 ON ON OFF ON 10 83 ON OFF OFF ON 12 100

Comp 1

OFF OFF OFF OFF OFF 0 0

ON ON OFF OFF OFF 4 20 ON OFF OFF OFF OFF 6 30 ON ON OFF ON OFF 10 50 ON OFF OFF ON OFF 12 60 ON ON OFF ON ON 14 70 ON OFF OFF ON ON 16 80 ON ON ON ON ON 18 90 ON OFF ON ON ON 20 100

Unloader

Lead Circuit Lag Circuit

Unloader

Comp 3 Comp 2 Comp 4

Unloader

Comp 2

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 Tabl e 21.

Checking Display Codes —

play codes, press the button located to the right of the LED display/set point board in the control box. See T a ble 22 for Operational Status Codes. See Table 23 for Diagnostic Codes.

Complete Unit Stoppage —

several conditions that can cause this situation to occur:

• Remote ON/OFF circuit in Unoccupied mode.

• Unit ON/OFF switch moved to OFF positio n.

• Programmed schedule at the timeclock.

• General power failure.

SYMPTOM(S) PROBABLE CAUSE(S) SOLUTION(S)

Controls do not seem to be operating.

Evaporator fan does not run.

Compressor does not run.

Condenser fans do not turn on.

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

To view the digital dis-

If the unit is of f, there are

Table 21 — Controls Troubleshooting

Remote on-off function may be keeping controls off.

1. Circuit breaker open.

2. Inverter overload (if equipped).

1. Circuit breaker is open.

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.

• Blown fuse in the control power feed.

• Open control circui t 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 h igh-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.

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.

Table 22 — 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

Restart Procedure —

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

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 s afety 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.

Diagnostic Codes —

Diagnostic codes are warnings of abnormal or fault conditions, and may cause eit her one ci rcuit or the whole unit to shut down. They are assigned code numbers as described below.

Tabl e 23 contains a description of each dia gnostic code error and possible cause. Manual reset is accomplished by moving the ON/OFF S witc h to t he O FF pos it ion, 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.

CODES 51, 52, 55, 56: COMPRESSOR FAILURE — If control relay (CR) opens while compressor should be oper ating, compressor will stop and microprocessor will energize alarm light and display a code of 51 , 52 , 55 or 56 (depending on compressor) when display button is pushed. The compressor will be lock ed off; to reset, th e ON-OFF switch must be tur ned 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, o n s ize 104 uni ts.

The microprocessor has also been programmed to indicate a compressor failure if CR switch is cl osed 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 pow er 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 the rmostat 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. Wiring Problem

— A wiring error or a loose wire may cause

the feedback circuit to be broken.

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.

Table 23 — Diagnostic Codes

DISPLAY DESCRIPTION OF FAILURE

51 55 52 56

59 60

63 64

70 71

72 75

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

Illegal unit configuration Unit will not start Manual Configuration error (see Note 1). Supply-air thermistor failure

Return-air thermistor failure Circuit 1 saturated condensing thermistor

Circuit 2 saturated condensing thermistor

Reset temperature thermistor failure Supply-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

ACTION TAKEN

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 ch arge, 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. T o 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/RESISTO R 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 23) will be displayed when the display button is pushed. The unit will be shut down. Thermistor fail ures will au tomatically reset once the error h as

been corrected. If a failure occurs, t he following are possible causes:

Thermistor or Resistor Failure

— A shorted or open ther-

mistor or resistor will cause the failure. Wiring Failure

— If a wiring error exists that causes a shorted

or open circuit, this will cause a failure. Processor Board Failure

— If circuitry on processor board

fails, this could cause an error.

The codes are designated as follows: 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 POTENTIOMETER

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 . T his error will automatically re set 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 therm istor will

cause the failure.

• Potentiometer Failure — If the potentiom eter 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

(hardware), an alarm will be detected.

CODE 82: SUPPLY-AIR TEMPERATURE SET POINT POTENTIOMETER FAILURE — If supply-air set point potentiometer (P1 — located on display board) fails, control will use a default value. A failure wil l cause an error code of 82 to be displayed on display board when display button is pushed; alarm light will also be energized. A failure is dete rmined 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 will be energized and an error code of 82 will be displayed when display button is pushed; the control will use a set point of 70 F. If set point is between –22 F and 45 F, control will use a set point of 45 F and no error code will be indicated. If potentiometer returns to nor mal , cont ro l wil l auto mati cal ly r ese t.

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

— A potentiometer 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 POTENTIOME-

TER FA ILURE — 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 energize alarm light and cause an error code of 83 to be displayed 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 84 will be displayed if display button is pushed, and reset will be terminated. The full-scale resistance of potentiometer is 10 Kohms, but when installed on the accessory board in parallel with the other 2 potentiometers, measured resistance will be 3.3 Kohms. This failure will automaticall y 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

— A potentiometer turned fully clockwise or counterclockwise is outside the valid range and will res ult in a fa ilur e.

Faulty Wiring

— If the wiring between the potent iometer and

the processor board is incorrect, a failure will result. Potentiometer Failure

— If potentiometer is shorted or open, a

failure will occur.

CODE 85: DEMAND LIMIT POTENTIOMETER (P4) FAILURE — Used only if demand limit is being used. If demand limit is used, DIP switch 5 must be in the ON position.

Tw o 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. The single-step control has a single potentiometer while 2-step control has 2 potentiometers (mounted on the demand limit board, see Fig. 28).

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 85 will be displayed when the display button is pushed, and demand limit will be terminated. If a failure occurs, it is probably due to one of the following:

Potentiometer Failure

— If a potentiometer is shorted or open,

a failure will occur. Incorrect Potentiometer Setting

— A potentiometer 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 po-

tentiometer is not installed, an error will occur. CODE 86: MINIMUM POSITION ECONOMIZER POTEN-

TIOMETER FAILURE — If potentiometer P5 (on accessory board) setting is less than 0% or greater than 100%, alarm light will be energized, a code of 86 will be displayed when display button is pushed and economizer outdoor 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-UP TEM PERATURE SET POINT FAIL-

URE — Applicable only if morning warm-up is used. Whether or not unit is equipped with electric re sistance heaters, use of the morning warm-up function is recommended if the unit is shut down at night or over weekends. In this application, cooling will remain off and the outdoor-air damper will stay closed until heat load from the occupied space elevates return-air temperature to the warm-up set point. If warm-up 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 87 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, c ontrol 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 s witch is in the O N position a nd 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 potentiome ter 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.

Thermistor Troubleshooting —

The VAV con trol system uses thermistors to measure temper atures of the entering and supply air, as well as the saturated condensing temperatures of the refrigerant circuits. The resistance versus tempera ture and electrical characteristics for all thermistors in the system are identical. To obtain an accurate reading, a highimpedance 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 19 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 asse mbly. Do not attempt to spli ce th e wir es or repa ir the assembly.

Electronic Controls Checkout —

The following will help determine whether a processor board, a rela y 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 th e Quick Test mode. This test will determine if all components are connected and ope rating 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.

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

To preve nt 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 CHEC KO UT — R efe r to Fig . 49 an d 50 for location of terminal pins and test points.

Step 1 — Check Transformer Inpu t 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 connector J4:

TERMINALS VOLTAGE (AC)

1 to 2 4 to 6 5 to 6 5 to 4

15.3 to 20.9

16.2 to 22.0

8.1 to 11.0

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 TP4

TP6 TP10 TP14 TP15

TP7

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

+10 +12

+5 +12 +12

–5*

6. If voltage is incorrect, replace processor board.

7. Turn power to ON position.

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 +3 vdc, reset power and recheck.

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

6. Turn power to ON position.

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 Test mode.

9. Place negative lead on t erminals shown in Table 24, and check voltage between TP15 and terminals shown in

Ta ble 23 on pin terminal connector J9. See Fig. 51 for J9 details.

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.

5. Place the other lead on termi nals shown in table below, and check voltage at pin terminals on pin terminal connector J10 (see Fig. 52 for pin terminal connector J10 details):

PIN TERMINAL VOLTAGE (DC)

17 18 20* 22* 24

*Voltage reading is dependent on the meter’s impedance. Readings may vary with different meters.

5 5

2.5

2.5 5

LEGEND

Pin Terminal Strip

J —

Test Pin

TP —

Fig. 49 — 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

Fig. 51 — Relay Board Pin Terminal Connector (J9)

J5J6

QUICK TEST

STEP NO.

NOTES:

1. Pins shown in All other pins will be energized continuously while at the proper quick test step. The control will only stay in the Quick Test routine for 10 minutes unless the display button is pressed.

2. Acceptable range for the voltage reading:

0 v — 0 to 4 v

12 v — 11 to 13 v

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

Table 24 — Voltage Reading

1.-2.3.

2.4.

2.5.

2.6.

2.7.

2.8.

2.9. 12

3.0.

3.1.

3.2.

3.3.

12345678910111213

00000000000012 000000120000012 000000012000012 0000000120120012 0 0 000 0 0120012012 0000000120001212

00000012000012

0000012000012

00120 0 0 0 12 0 0 0 0 12 0000120 0 12 0 0 0 0 12 0000012012000012

boldface type

will only be energized for 10 seconds.

J9 PIN NUMBERS

K1 K2 K3

LEGEND

Control Relay

CR —

Pin Terminal Strip

J —

Relay

K —

Fig. 50 — Relay Board Test Points

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 Test mode.

5. Place the other lead on termi nals shown in table below, and check voltage at pin terminals on terminal connector J3:

PIN TERMINAL VOLTAGE (DC)

1* 2.5

35 65

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 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 thermistor connections removed in Step 2.

8. Turn power to ON position.

Table 25 — Pin Terminal Connector J1 Voltages

TERMINAL

1 2 6 7 8

9 10 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 26, and check the voltages.

6. If voltages are incorrect (per Table 26), replace processor board.

7. Turn power to OFF position, and replace the plugs removed in Step 2.

8. Turn power to ON position.

Table 26 — Pin Terminal Connector J2 Voltages

Fig. 52 — Display Board Pin Terminal Connector

(J10)

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 connec tors 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 27 and check resistances at each quick test step.

6. If these resistances are not correct and relay board outputs 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 Test mode.

6. Place other meter lead on terminals shown in Table 28 and check resistance at each quick test step.

7. If these resistances are not correct and relay board outputs 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 27 — Terminal Strip J6 Connection

Resistance Reading

QUICK TEST

STEP NO.

1. to 2.3.

2.4.

2.5.

2.6.

2.7.

2.8.

2.9.

3.0.

3.1.

3.2.

3.3.

LEGEND

∞

Infinity

—

NOTE: Pins shown in 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

∞∞∞∞∞∞∞∞ ∞∞∞∞∞∞ ∞∞∞∞∞∞ ∞∞∞∞∞∞∞∞ ∞∞∞∞∞∞∞∞ ∞∞∞∞∞∞∞∞

∞ ∞∞0∞∞∞∞∞

∞∞∞∞0∞∞∞ ∞∞∞∞∞0∞∞

boldface

J6 PIN NUMBERS

∞

∞∞∞∞∞∞∞

∞∞∞∞∞∞

type will be energized for only

Table 28 — Terminal Strip J5 Connector

Resistance Reading

QUICK TEST

2.9. to 3.3.

LEGEND

∞

Infinity

—

STEP NO.

1. to 2.5.

2.6

2.7.

2.8.

J5 PIN NUMBERS

12345

∞∞∞∞

00 0 0

∞∞

∞

∞∞ ∞∞

0 0

∞

Step 2 — Check the Display LEDs

1. Enter Quick Test mode.

2. If 88 is not displayed, replace display board.

Step 3 — Check Set Point Potentiometer

— Advance the 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.

ACCESSORY BOARD CHECKOUT — The accessory board can be completely checked using quick test steps 2.0., 2.2., and

2.3. It can also be checked out as follows:

1. Remove the a ccessory board connector fr om 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 ohmme ter 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 read-

ing, 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 th e 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 con-

nector or the processor board when taking the vol tage

readings.

T est under the following conditions:

BLU RED

YEL

AUX. SWITCH

LIMIT SWITCHES

CAPACITOR

CW WINDING (OPEN)

CCW WINDING (CLOSE)

FEEDBACK POTENTIOMETER

ECONOMIZER MOTOR

BRAKE WINDING

LEGEND

Fig. 53 — Damper Motor Connection Diagram (VAV)

CCW —

Counterclockwise

CW —

Clockwise

• 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%.

T erminal 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 —

To test operation of

enthalpy sensor, see Table 29.

Table 29 — Enthalpy Sensor Checkout

TEST

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:

Economizer Motor —

EXPECTED RESULT

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.

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

Jumper 1 to Mot or drives open; if not, 2 at motor replace motor.

B Motor T est

A Expected Result and Response

B Expected Result and Response Jumper 1 to Motor drives closed; if not, 3 at motor replace motor.

Supply Fan Variable Frequency Drive

Factory-installed optional VFD is located nea r 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 30 for listing of Carrier-specific default values.

ST ANDARD TRANSDUCER CONTROL — The VFD mon-

4-20mA

P24

RES

RCH

P24

LOW

FLA

FLB

FLC

P24

RES

RCH

P24

LOW

FLA

FLB

FLC

4-20mA

Fig. 54 — Supply Fan Variable Frequency Drive

Terminal Block (Size 034-048 Units)

Fig. 55 — Supply Fan Variable Frequency Drive

Terminal Block (Size 054-104 Units)

itors 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 factoryinstalled tubing section. The pressure transducer ’s high pressure reference point must be field-connected to the duct pressure pick-up (field-supplied and installed in the supply duct).

The DP transducer monitors the static pressure in the supply duct and provides a 4 to 20 mA signal directly to the VFD. (Refer to Table 13 for transducer output signal [mA] for actual duct static pressure.) The i nternal logic of the VF D compares this signal representing actual duct pressure to the user-configured DP set point. The VFD automatically adjusts its output to t he 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 and lock out all power to the Carrier rooftop unit.

2. Remove the VFD access cover.

Ensure the “CHARGE” lamp on the VFD is unlit. This may up to 4 minutes. The “CHARGE” lamp indicates that the main capacitors in the V FD are charged. Internal components of the VFD should not be touched until the “CHARGE” lamp is co mpletely out. Electr ical shock can cause injury or death.

3. Install a jumper across S2-CC (see Fig. 54 and 55 for VFD terminal board connections).

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

5. Remove other end of the same cable from the pressur e sensor.

6. Connect field supplied speed reference (4 to 20 mA) across terminals IV-CC.

7. Disable the supply fan motor operation.

8. Reconnect power to the unit and VFD.

9. Reprogram the VFD t o accept an external reference (in the Utility parameters group [Gr.Ut], set parameter item Fnod [no.312] = 4).

10. Enable supply fan motor and return power to the unit.

SUPPL Y FAN MOTOR OVERLOAD PROTECTION — The VFD provides operating overload protection for the supply fan motor. The factory has programmed the VFD overload function to match the factory-installed motor (motor size and efficiency). If the supply fan motor is changed from the 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.

VFD OPERATION — When troubleshooting the VFD, che ck 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 ins talled from terminals CC-ST (factory supplied) (see Fig. 54 and 55).

2. Proper rotation jumper is installed at t erminals R-CC (reverse rotation, factory supplied) or terminals F-CC (forward rotation, factory supplied).

UNIT SIZES ROTATION JUMPER

034-048 054-074 078-104

Reverse R-CC

Forward F-CC Forward F-CC

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

4. A 4 to 20 mA signal is applied across terminals IV-CC (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 ‘‘Remot e’’ (press the ‘‘Speed Ctrl’’ button until LED ‘ ‘Re mote ’’ 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).

Table 30 — Carrier Default Program Parameter Values (Supply Fan VFD)

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 32

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*

VFD OPERATIONAL STATUS — The VFDs contain extensive 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).

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 o riginal 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 t he VFD defaults to the general Carrier use values. These are st ored 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 T able 31 for items requiring manual adjustment.

Power Exhaust Variable Frequency Drive (48FM and 50FM,FS)

STANDARD TRANSDUC ER CONTRO L — The VFD monitors and controls building pressure (BP) via a differential pressure transducer. The pressure transducer is located in the auxiliary control box. The pressure transducer’s high-pressure reference port is connected to the outside of the unit cabinet by a factory-installed tubing section. The pressure transducer’s low-pressure reference point must be field-connected to the building pressure pick-up (field-supplied and installed in the building).

The BP transducer monitors the static pressure in the occupied space and provides a 4 to 20 mA signal directly to the power exhaust VFD. (Refer to Table 30 for transducer output signal [mA] for actual building static pressure.) The internal

logic of the power exhaust VFD compares this signal representing actual duct pressure to the user-configured BP set point. The power exhaust VFD automatically adjusts its output to the power exhaust fan motor to maintain the desired BP set point. When operating with the factory-standard BP transducer, the internal PID logic of the power exhaust VFD is enabled.

EXTERNAL SIGNAL CONTROL — If the power exhaust VFD is to be controlled by an external control system other than the factory-supplied pressure transducer, the internal PID logic function of the power exhaust VFD must be disabled. To disable the PID control:

1. Disconnect and loc k out all power to the Carrier rooftop unit.

2. Remove the VFD access cover.

Ensure the “CHARGE” lamp on the VFD is unlit. This may up to 4 minutes. The “CHARGE” lamp indicates t hat the main capacitors in the V FD are c harged. Internal components of the VFD should not be touched until the “CHARGE” lamp is completely out. Electrical shock can cause injury or death.

3. Install a jumper across S2-CC (see Fig. 56 for power exhaust VFD terminal board connections).

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

5. Remove other end of the same cable from the pressure sensor.

6. Connect field-supplied speed reference (4 to 20 mA) across terminals IV-P24.

7. Disable the supply fan motor operation.

8. Reconnect power to the unit and power exhaust VFD.

9. Reprogram the powe r exhaust VFD to accept an external reference (in the Utility parameters group [GR.Ut], set parameter item Fnod [no.312] = 4).

10. Enable supply fan motor and return power to the unit.

Table 31 — Supply Fan VFD Required

User Adjusted Defaults

SIZES ITEM

All

054-104

Motor overload settings (see Table 32)

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)

Table 32 — Supply Fan Motor Overload Settings

UNIT 48/50

FK,FY,

JK,JY

FKX,FKY,

JKX,JKY

LEGEND

IFM —

DESIGNATION

Indoor Fan Motor

UNIT

VOLTAGE

AND

Model No.

Position 12

5 And N 82.0 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

IFM HP

DESIGNATION

Model No.

Position 15

tHr1

SETTING

POWER EXHAUST FAN MOTOR NO. 1 OVERLOAD

4-20mA

P24

RES

RCH

P24

LOW

FLA

FLB

FLC

Fig. 56 — Variable Frequency Drive Terminal Block

PROTECTION — The VFD provides operating overload protection for the supply fan motor. The factory has programmed the power exhaust VFD overload function to match the factory-installed motor (motor size and efficiency). If the power exhaust 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 33 — Carrier Power Exhaust VFD Default Program Parameter Values

PARAMETER GROUP PARAMETER DEFAULT VALUE

ACC1 60.0 Sec DEC1 60.0 Sec

UL 59.8 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 98%

F-P4 60 Hz

tHr1 See Table 35

StC1 0

StL1 110% OLN 1

tYP 5*

FH 60 Hz

Pt 12

FbP1 1*

Fbin 2

GP .30

Gl 2 sec

GA 0

GFS 80

P1LL 10

PuL 1

PuUl 10

PuLL 10

Fsor 60 Hz

Fr 0*

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

Ot1 4* Ot2 2*

Ot2d 5*

Ot2H 100*

LF 15*

UuC 1*

UuCt 2

ArSt 3 Cnod 1* Fnod 2* bLPn 1*

POWER EXHAUST VFD OPERATION — When troubleshooting the power exhaust VFD, check first that all required conditions for power exhaust VFD operation are satisfied.

For the power exhaust VFD to run, the following conditions

must be met at the power exhaust VFD:

1. Drive enable jumper is installed from terminals ST-C C (factory supplied) (see Fig. 56).

2. Pro per rotation jumper is installed at term inals R-CC (reverse rotation, factory supplied).

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

4. A 4 to 20 mA signal is applied across terminals IV-P24 (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. Building Pressure set point established by user, or use factory default (30 Hz indicating 0.0 in. wg) (see T able 15).

POWER EXHAUST VFD OPERATIONAL STATUS — The power exhaust VFDs contain extensive self-diagnostic functions which are accessed through the power exhaust VFD display panel (located on the front of the power exhaust VFD or at a remote location when the accessory remote display package has been installed.)

When power is first supplied to the power exhaust VFD, the display automatically starts with the frequency monitor function of its standard monitor mode. In t he 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 POWER EXHAUST VFD DEFAULTS — The original factory configuration values are saved in the memory of the power exhaust 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 power exhaust 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 power exhaust VFD defaults to the general Carrier use values. These are stored in an OP TION 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 s 34 and 35 for items requiring manual adjustment.

Table 34 — Power Exhaust VFD Required

User Adjusted Defaults

UNIT ITEM

Motor Overload Settings (See Table 35) Gr.St/Ot1 = 4 Gr.St/Ot2 = 2

ALL

Gr.St/Ot2d = 5 Gr.St/Ot2H = 100 Gr.St/LF = 15 SEtP/UL = 59.8 SEtP/P4 = 98

Table 35 — Power Exhaust Motor

Overload Settings

MODEL NUMBER

POSITION 16

H, T

J, V

K, W

L, X M, Y

Unit Wiring —

TOTALHPMOTOR HP

(ea)

20 10 97.3 30 15 100.0 40 20 100.0 50 25 93.5 60 30 92.3

tHr1

SETTING

A typical wiring schematic is shown in

Fig. 57.

LEGEND AND NOTES FOR FIG. 57

ALM — C — CB — CCB — COMP — CH — CR — DPS — DPT — EAT — EC — ECR — EOR — EQUIP — FS — GND — HIR — HPS — HR — HTR — IDC — IDM — IFC — IFCB — IFM — IGV —

Alarm Contactor Circuit Breaker Control Circuit Breaker Compressor Crankcase Heater Control Relay Differential Pressure Switch Discharge Pressure Transducer Enering-Air Temperature Enthalpy Control Economizer Close Relay Economizer Open Relay Equipment Fan Status Switch Ground Heat Interlock Relay High-Pressure Switch Heater Relay Heater Induced Draft Contactor Induced Draft Motor Indoor (Evaporator) Fan Contactor Indoor Fan Circuit Breaker

IGVM — LAT — LPS — MTR — MV — NC — NO — OFC — OFM — OMR — PCB — PEC — PEDM — PEM — P, PL — RCB — RES — RFC — RFM — SCT — TB — TRAN — U — VFD —

Inlet Guide Vanes Motor Leaving-Air Temperature Low-Pressure Switch Motor Main Valve Normally Closed Normally Open Outdoor Fan Contactor Outdoor (Condenser) Fan Motor Outdoor Motor Relay Power Exhaust Circuit Breaker Power Exhaust Contactor Power Exhaust Damper Motor Power Exhaust Motor Plug Return Fan Circuit Breaker Resistor Return Fan Contactror Return Fan Motor Saturated Condensing Thermistor Terminal Block Transformer Unloader Variable Frequence Drive

Indoor Fan Motor Field Wiring Inlet Guide Vanes Factory Wiring

NOTES:

1.Connect TRAN1 to for 460 v units. Connect to for 230 v

units. If 208/230 v units are run with a 208 v power supply con-

nect to .

2.Connect TRAN2 to BLK lead for 460 v units. Connect to ORN lead for 230 v units. If 208/230 v units are run with a 208 v power 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.

Fig. 57 — Typical Wiring Schematic; 48FK,JK and 50FK,FY,JK,JY Units (054-074 Shown)

Fig. 57 — 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 t he equipment discussed in this manual, including:

• Unit Familiarization • Maintenance

• Installation Overview • Operating Sequence

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

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. 534-763 Printed in U.S.A. Form 48/50F,J-3T Pg 62 3-00 Replaces: 48/50F,J-1T

START-UP CHECKLIST

MODEL NO.: _____________________________________ DATE: ___________________________________________

SERIAL NO.: ______________________________________ TECHNICIAN:_____________________________________

I. PRE-START-UP:



VERIFY THA T UNIT IS LEVEL



VERIFY THA T ALL PACKING MA TERIALS HAVE BEEN REMOVED FROM UNIT



LOOSEN ALL SHIP PING HOL DDOWN BOLTS AND REMOV E SHI PPI NG BR ACKE TS PE R INS TRUC TION S



VERIFY THAT COMPRESSOR SUSPENSION SPRINGS HAVE BEEN LOOSENED PER INSTRUCTIONS



VERIFY OPENING OF ECONOMIZER HOODS



VERIFY INSTALLATION OF EXHAUST HOODS



CONFIRM THAT TUBING FOR SPACE AND SUPPLY DUCT PRESSURES HAS BE EN INS TALLED



VERIFY THA T CONDENSATE CONNECTION IS INSTALLED PER INSTRUCTIONS



VERIFY THA T POWER SUPPLY MATCHES UNIT DATA PLATE



VERIFY THA T ALL ELECTRICAL CONNECTIONS AND TERMINALS ARE TIGHT



CHECK GAS PIPI NG FO R LEA KS (48 FK, JK ON LY)



CHECK THAT INDOOR-AIR FILTERS ARE CLEAN AND IN PLACE



CHECK FAN WHEEL AND PROPELLER FOR LOCATION IN H OUSING/ORIFICE, AND VERIFY SET SCREWS A RE TIGHT



VERIFY THA T FAN SHEA VES ARE ALIGNED AND BELTS ARE PROPERLY TENSIONED



OPEN SUCTION , DI SC HARGE , AN D LI QUI D LI NE SE RVICE VALVES



CHECK COMPR ESSO R OIL LEV EL S IGH T GL ASS AN D VER IF Y PR OPER LEVE L



VERIFY THA T CRANKCASE HEATERS HAVE BEEN ENERGIZED FOR 24 HOURS



CHECK VOL TAGE IMBALANCE LINE-TO- LI NE VO LTS: AB (AB + AC + BC) /3 = AVERAGE VOLTAG E = MAXIMUM DEVIATION FROM AVERAGE VOL TAGE = VOLTAGE IMBALANCE = 100 X (MAX DEVIA TION)/(AVERAGE VOLTAGE) = IF OVER 2% VOLTAGE IMBALANCE, DO NOT ATTEMPT TO ST ART SYSTEM!

CALL LOCAL POWER COMPANY FOR ASSISTANCE.

VACVBCV

II. PRELIMINARY CHECKLIST ITEMS:

CONTROL SETTINGS



DIP SWITCHES SET TO MA TCH INSTALLED ACCESSORIES:

SUPPLY AIR SET POINT RESET (DIP SWITCH NO. 4 ON) MORNING W A RM-UP (DIP SWITCH NO. 4 ON) DEMAND LIMIT (DIP SWITCH NO. 5 ON)



SUPPLY AIR SET POINT (P1) SET BETWEEN 45 AND 70 F



ECONOMIZER MINIMUM POSITION (P5) SET PER PLANS



SUPPLY AIR SET POINT RESET SETTINGS:

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



MORNING WARM-UP TEMPERA TURE (TYPICALLY 50 TO 65 F)



IGV/VFD DUCT PRESS URE SE T PO INT PE R PLAN S



BUILDING PRESSURE (MODULATING POWER EXHAUST) SET PER PLANS



DEMAND LIMIT SETTINGS PER PLAN:

SINGLE STE P DEM AND LIM IT ( P 4) S ET ( TYP IC ALLY 25 T O 50 %) TWO-STEP DEMAND LIMIT

DLCM-P1 SET (TYPICALL Y 50 TO 75%) DLCM-P2 SET (TYPICALL Y 0 TO 25%)



OCCUPIED/UNOCCUPIED SWITCH INST ALLED PER FIG. 23 (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

SUPPL Y FAN AMPS EXHAUST FAN AMPS ELECTRIC HEA T AMPS L1 L2 L3 (50 SERIES UNITS ONLY)

TEMPERATURES

OUTDOOR-AIR TEMPERATURE F DB (Dry-Bulb) RETURN-AIR TEMPERA TURE COOLING SUPPL Y AIR

PRESSURES

GAS INLET PRESSURE IN. WG (48 SERIES UNITS ONL Y ) GAS MANIFOLD PRESSURE STAGE NO. 1

UNITS ONLY) REFRIGERANT SUCTION CIRCUIT NO. 1 REFRIGERANT DISCHARGE CIRCUIT NO. 1



VERIFY REFRIGERANT CHARGE USING CHARGING CHARTS IN UNIT INST ALLATION INSTRUCTIONS

GENERAL



ECONOMIZER MINIMUM VENT SETTING TO JOB REQUIREMENTS

F DB F WB (Wet-Bulb) F

IN. WG STAGE NO. 2 IN. WG (48 SERIES

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

CUT ALONG DOTTED LINE CUT ALONG DOTTED LINE

IV. NOTES

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. 534-763 Printed in U.S.A. Form 48/50F,J-3T Pg CL-2 3-00 Replaces: 48/50F,J-1T

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Carrier 48JK048, 50FY034, 50FY048, 50JY034, 50JY048 Operating And Troubleshooting Manual

Specifications and Main Features

Frequently Asked Questions

User Manual