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66389-BIM-C-1208

32

Johnson Controls Unitary Products

OPERATION

SEQUENCE OF OPERATIONS OVERVIEW

For the DW series of units, the thermostat makes a circuit
between "R" and "Y1" for the first stage of cooling. 

The call is passed to the unit control board (UCB), which then
determines whether the requested operation is available and,
if so, which components to energize.

For gas heating, the UCB monitors the "W1" call but does not
handle the operation of the gas furnace. An ignition control
board controls the gas heater operation. For electric heat
units, the UCB passes the call to the electric heater. In both
cases, when the "W1" call is sensed, the indoor air blower is
energized following a specified heating delay.

If at any time a call for both heating and cooling are present,
the heating operation will be performed. If operating, the cool-
ing system is halted as with a completion of a call for cooling.
Heating always takes priority.

COOLING SEQUENCE OF OPERATION

CONTINUOUS BLOWER

By setting the room thermostat fan switch to "ON," the supply
air blower will operate continuously.

INTERMITTENT BLOWER

With the room thermostat fan switch set to "AUTO" and the
system switch set to either the "AUTO" or "HEAT" settings,
the blower is energized whenever a cooling or heating opera-
tion is requested. The blower is energized after any specified
delay associated with the operation.

When energized, the indoor blower has a minimum run time
of 30 seconds. Additionally, the indoor blower has a delay of
10 seconds between operations.

TABLE 21: ADDITIONAL STATIC RESISTANCE

CFM

Cooling Only

1

Economizer

2

 

3

Electric Heat KW

2

18

24

36

54

3700

0.20

0.04

0.18

0.21

0.22

0.26

3900

0.23

0.04

0.20

0.23

0.24

0.28

4100

0.25

0.04

0.22

0.25

0.26

0.31

4300

0.28

0.05

0.24

0.28

0.29

0.34

4500

0.30

0.05

0.26

0.30

0.31

0.37

4700

0.33

0.05

0.29

0.33

0.34

0.40

4900

0.36

0.05

0.31

0.35

0.37

0.43

5100

0.39

0.06

0.34

0.38

0.40

0.46

5300

0.42

0.06

0.37

0.41

0.43

0.49

5500

0.45

0.06

0.40

0.44

0.46

0.53

5700

0.48

0.06

0.43

0.47

0.49

0.56

5900

0.52

0.07

0.46

0.50

0.53

0.59

6100

0.56

0.07

0.49

0.53

0.56

0.62

6300

0.60

0.07

0.53

0.56

0.59

0.65

1.

Add these resistance values to the available static resistance in the respective Blower Performance Tables.

2.

Deduct these resistance values from the available external static pressure shown in the respective Blower Performance Table.

3.

The pressure drop through the economizer is greater for 100% outdoor air than for 100% return air. If the resistance of the return 
air duct system is less than 0.25 IWG, the unit will deliver less CFM during full economizer operation.

TABLE 22: MOTOR SHEAVE DATUM DIAMETERS

1VM50x7/8

(3 HP Motor)

1VP56x1-1/8

(5 HP Motor)

Turns Open

Datum 

Diameter

Turns Open

Datum 

Diameter

0

4.4

1

5.3

1/2

4.3

1-1/2

5.2

1

4.2

2

5.1

1-1/2

4.1

2-1/2

5.0

2

4.0

3

4.9

2-1/2

3.9

3-1/2

4.8

3

3.8

4

4.7

3-1/2

3.7

4-1/2

4.6

4

3.6

5

4.5

4-1/2

3.5

5-1/2

4.4

5

3.4

6

4.3

Summary of Contents for DW-12

Page 1: ...owing pages for a complete Table of Contents NOTES CAUTIONS AND WARNINGS The installer should pay particular attention to the words NOTE CAUTION and WARNING Notes are intended to clarify or make the installation easier Cautions are given to prevent equipment damage Warnings are given to alert installer that personal injury and or equipment damage may result if installation procedure is not handled...

Page 2: ...PY SENSORS 33 ECONOMIZER SINGLE OR DUAL WITH POWER EXHAUST 33 MOTORIZED OUTDOOR AIR DAMPERS 33 COOLING OPERATION ERRORS 33 HIGH PRESSURE LIMIT SWITCH 33 LOW PRESSURE LIMIT SWITCH 34 FREEZESTAT 34 LOW AMBIENT COOLING 34 SAFETY CONTROLS 34 COMPRESSOR PROTECTION 34 FLASH CODES 34 RESET 34 ELECTRIC HEATING SEQUENCE OF OPERATIONS 34 ELECTRIC HEATING OPERATION ERRORS 35 TEMPERATURE LIMIT 35 SAFETY CONTR...

Page 3: ...OW CHART 45 32 TRIP FAILURE FLOW CHART 46 LIST OF TABLES Tbl Pg 1 UNIT VOLTAGE LIMITATIONS 9 2UNIT TEMPERATURE LIMITATIONS 9 3 6 POINT LOAD WEIGHT 10 4 UNIT WEIGHTS 10 5 4 POINT LOAD WEIGHT 10 6 UNIT CLEARANCES 11 7 CONTROL WIRE SIZES 15 8 ELECTRICAL DATA DW 12 12 1 2 TON WITHOUT POWERED CONVENIENCE OUTLET 19 9 ELECTRICAL DATA DW 12 12 1 2 TON WITH POWERED CONVENIENCE OUTLET 19 10 PHYSICAL DATA 20...

Page 4: ...sit If damage is evident the extent of the damage should be noted on the carrier s freight bill A separate request for inspection by the carrier s agent should be made in writing Should overheating occur or the gas supply fail to shut off shut off the manual gas valve to the furnace before shutting off the electrical supply Do not use this furnace if any part has been under water Immediately call ...

Page 5: ...ental electric heat or a forced air furnace 2 For outdoor installation only 3 For installation on combustible material and may be installed directly on combustible flooring or in the U S on wood flooring or Class A Class B or Class C roof cov ering materials 4 For use with natural gas convertible to LP with kit The installer should pay particular attention to the words NOTE CAUTION and WARNING NOT...

Page 6: ...ptions Installed Installation Options B Option 1 C Option 2 D Options 1 2 E Option 3 F Option 4 G Options 1 3 H Options 1 4 J Options 1 2 3 K Options 1 2 4 L Options 1 3 4 M Options 1 2 3 4 N Options 2 3 P Options 2 4 Q Options 2 3 4 R Options 3 4 S Option 5 T Options 1 5 U Options 1 3 5 V Options 1 4 5 W Options 1 3 4 5 X Options 3 5 Y Options 4 5 Z Options 3 4 5 1 Disconnect 2 Non Pwr d Conv Out...

Page 7: ...enser coil external protective covering prior to operation 4 Remove the toolless doorknobs and instruction packet prior to installation LIMITATIONS These units must be installed in accordance with the following In U S A 1 National Electrical Code ANSI NFPA No 70 Latest Edition FIRE OR EXPLOSION HAZARD Failure to follow the safety warning exactly could result in serious injury death or property dam...

Page 8: ... product for process cooling applications com puter rooms switchgear etc please reference applications bulletin AE 011 07 or call the applica tions department for Unitary Products 1 877 UPG SERV for guidance Additional accessories may be needed for stable operation at temperatures below 30 F FIGURE 3 DW 12 COMPONENT LOCATION Simplicity Control board w screw connectors for T stat wiring and Network...

Page 9: ...e provided for this purpose LENGTH OF FORKS MUST BE A MINIMUM OF 60 INCHES TABLE 1 UNIT VOLTAGE LIMITATIONS Power Rating1 1 Utilization range A in accordance with ARI Standard 110 Minimum Maximum 208 230 3 60 187 252 460 3 60 432 504 575 3 60 540 630 TABLE 2 UNIT TEMPERATURE LIMITATIONS Temperature Min Max Wet Bulb Temperature F of Air on Evaporator Coil 57 72 Dry Bulb Temperature F of Air on Cond...

Page 10: ...rgest gas heat option A B C D E F DW 12 184 210 246 323 275 242 FIGURE 5 UNIT 6 POINT LOAD FIGURE 6 UNIT CENTER OF GRAVITY A B C F E D LEFT FRONT 60 25 LEFT FRONT Do not permit overhanging structures or shrubs to obstruct condenser air discharge outlet combustion air inlet or vent outlets Excessive exposure to contaminated combustion air will result in safety and performance related prob lems To m...

Page 11: ...Outlet Power Entry 7 8 For Gas Pipe Entry see DETAIL A For Baserail Dimensions see DETAIL B FRONT LEFT Power Entry 2 1 2 Control Entry 7 8 For Drain Dimensions see DETAIL C TABLE 6 UNIT CLEARANCES Top1 1 Units must be installed outdoors Overhanging struc ture or shrubs should not obstruct condenser air dis charge outlet 72 Right 12 Front2 2 The products of combustion must not be allowed to accumul...

Page 12: ...INGS FROM ABOVE Return Air Supply Air 32 11 16 6 13 16 6 13 16 6 13 16 21 3 16 19 3 16 17 3 16 7 1 8 14 23 32 16 3 8 18 1 16 19 5 8 63 1 2 27 1 2 18 24 21 12 5 16 LEFT FRONT Bottom Condensate Drain Bottom Power Control and Convenience Outlet Wiring Entries Bottom Gas Supply Entry ...

Page 13: ...ngs DUCT COVERS Units are shipped with the side duct openings covered and a covering over the bottom of the unit For bottom duct applica tion no duct cover changes are necessary For side duct application remove the side duct covers and install over the bottom duct openings The panels removed from the side duct connections are designed to be reused by securing each panel to its respective downflow ...

Page 14: ...R S E C T I O N I N S U L A T E D D E C K U N D E R C O N D E N S E R S E C T I O N F R O N T R I G H T S U P P L Y R E T U R N 7 6 5 8 9 4 5 0 1 2 3 0 1 2 6 4 1 4 5 9 1 4 1 0 2 3 4 2 6 8 0 5 8 2 T Y P F R O N T R I G H T S U P P L Y R E T U R N When fastening ductwork to side duct flanges on unit insert screws through duct flanges only DO NOT insert screws through casing Outdoor duct work must be...

Page 15: ...mostat should be located on an inside wall approxi mately 56 inch above the floor where it will not be subject to drafts sun exposure or heat from electrical fixtures or appli ances Follow the manufacturer s instructions enclosed with thermostat for general installation procedure Seven 7 color coded insulated wires should be used to connect the thermo stat to the unit Refer to Table 7 for control ...

Page 16: ...e power wiring fuses and disconnect switch 208 230 3 60 and 380 415 3 50 units control transformers are factory wired for 230v and 415v power supply respectively Change tap on transformer for 208 3 60 or 380 3 50 oper ation See unit wiring diagram Avoid damage to internal components if drilling holes for disconnect mounting When connecting electrical power and control wiring to the unit water proo...

Page 17: ...OSTAT O C C W 1 W 2 Y 1 G Y 2 X R S D C R E M O T E M I N P O S W 1 W 2 Y 1 G Y 2 C U N I T C O N T R O L B O A R D T S T A T R H R C FIGURE 18 FIELD WIRING DISCONNECT COOLING UNIT WITH WITHOUT ELECTRIC HEAT TERMINAL BLOCK TB1 FACTORY OR FIELD SUPPLIED DISCONNECT GROUND LUG THREE PHASE POWER SUPPLY ...

Page 18: ...M C 1208 18 Johnson Controls Unitary Products FIGURE 19 FIELD WIRING DISCONNECT COOLING UNIT WITH GAS HEAT L1 T1 L2 T2 T3 L3 FACTORY OR FIELD SUPPLIED DISCONNECT THREE PHASE POWER SUPPLY GROUND LUG CONTACTOR 1M ...

Page 19: ...Min Circuit Ampacity Amps FLA 208 20 0 146 0 1 5 230 460 575 Voltage Compressors OD Fan Motors Supply Blower Motor FLA 1 1 TABLE 9 ELECTRICAL DATA DW 12 12 1 2 TON WITH POWERED CONVENIENCE OUTLET RLA LRA FLA 3 5 3 5 3 5 3 5 3 5 ea ea ea HP HP HP HP HP HP HP HP HP HP None 71 9 77 1 77 4 82 6 90 90 90 100 2TP04521825 13 5 37 5 73 0 79 5 79 8 86 3 90 90 90 100 2TP04522425 18 0 50 0 88 6 95 1 95 5 102...

Page 20: ...data TABLE 10 PHYSICAL DATA Component Model DW 12 Evaporator Blower Blower Centrifugal Dia X Wd in 15 x 15 Motor Standard HP 3 Motor Optional HP 5 Evaporator Coil Rows 4 Fins per Inch 15 Height in 40 Face Area ft 2 each 13 2 Condenser Fan 4 per Unit Propeller Dia in each 24 Motor HP each 1 3 CFM Nominal each 3500 Condenser Coil 2 per unit Rows each 2 Fins per Inch 15 Height in each 36 Face Area ft...

Page 21: ...y NOTE Maximum capacity of pipe in cubic feet of gas per hour based upon a pressure drop of 0 3 inch W C and 0 6 specific gravity gas NOTE There may be a local gas utility requirement specify ing a minimum diameter for gas piping All units require a 3 4 inch pipe connection at the entrance fitting Line should not be sized smaller than the entrance fitting size TABLE 12 GAS HEAT APPLICATION DATA Un...

Page 22: ...be converted in the field for use with LP gas with accessory kit model number 1NP0441 All LP gas equipment must conform to the safety standards of the National Fire Protection Association For satisfactory operation LP gas pressure must be 10 5 inch W C at the unit under full load Maintaining proper gas pressure depends on three main factors 1 The vaporization rate which depends on the temperature ...

Page 23: ...d Outdoor Damp ers accessories include complete instructions for installation ECONOMIZER The Economizer can be a factory installed option or a field installed accessory If factory installed refer to the instruc tions included with the outdoor air hood to complete the assembly Field installed Economizer accessories include complete instructions for installation There are two Economizer options 1 Do...

Page 24: ...justment Screw fully clockwise This will allow 2nd stage cooling to operate With power exhaust option each building pressurization requirement will be different The point at which the power exhaust comes on is determined by the econo mizer damper position Percent Open The Exhaust Air Adjustment Screw should be set at the Percent Open of the economizer damper at which the power exhaust is needed It...

Page 25: ...C D D C C B B A A CONTROL CURVE CONTROL POINT APPROX 0 F 0 C AT 50 RH A D C B 63 17 73 23 70 21 67 19 FIGURE 23 HONEYWELL ECONOMIZER CONTROL W7212 N1 N P1 P EXH Set EXH Min Pos IAQ Max IAQ IAQ Min Free Cool T T1 AQ1 AQ SO SO SR SR A B C D TR TR1 24 Vac HOT 24 Vac COM EF EF1 2 3 4 5 1 Exhaust Air Adjustment Screw Exhaust Air LED Damper Min Position Screw Indoor Air Quality Max Adjustment Screw Indo...

Page 26: ...ure 24 Scroll compressors require proper rotation to oper ate correctly Units are properly phased at the fac tory Do not change the internal wiring to make the blower condenser fans or compressor rotate cor rectly TABLE 14 SUPPLY AIR LIMITATIONS Unit Minimum Maximum DW 12 3750 6250 FIGURE 24 BELT ADJUSTMENT Procedure for adjusting belt tension 1 Loosen six nuts top and bottom A 2 Adjust by turning...

Page 27: ...RFORMANCE1 2 ESP3 TURNS OPEN4 0 1 2 3 4 5 CFM W5 BHP CFM W5 BHP CFM W5 BHP CFM W5 BHP CFM W5 BHP CFM W5 BHP 0 4 5994 5400 5 79 5565 4369 4 69 5488 4169 4 47 5264 3599 3 86 4990 3085 3 31 4738 2812 3 02 0 6 5824 5216 5 59 5368 4186 4 49 5289 3991 4 28 5049 3437 3 69 4763 2937 3 15 4491 2655 2 85 0 8 5641 5022 5 39 5170 4012 4 30 5076 3807 4 08 4822 3272 3 51 4528 2790 2 99 4235 2497 2 68 1 0 5444 4...

Page 28: ...variable pitch motor sheave where 0 Turns Open is fully closed 5 W Watts TABLE 18 DW 12 12 1 2 TON OPTIONAL MOTOR SIDE SHOT BLOWER PERFORMANCE1 2 ESP3 TURNS OPEN4 0 1 2 3 4 5 CFM W5 BHP CFM W5 BHP CFM W5 BHP CFM W5 BHP CFM W5 BHP CFM W5 BHP 0 4 6447 5315 5 70 6207 4760 5 1046 5966 4205 4 51 5717 3716 3 98 5470 3307 3 55 0 6 6110 4917 5 27 5965 4464 4 79 5740 4023 4 31 5430 3501 3 75 5126 3054 3 28...

Page 29: ... A54 5 1725 87 1 15 184T 4 3 5 3 1 1 8 1VP56 6 7 1 BK77 BX55 TABLE 20 POWER EXHAUST SPECIFICATIONS POWER EXHAUST MODEL VOLT PHASE MOTOR ELECTRICAL FUSE SIZE CFM 0 1 ESP HP RPM1 1 Motors are multi tapped and factory wired for high speed QTY LRA FLA MCA 2PE0473125 208 230 1 0 75 1075 1 24 9 5 0 6 3 10 3 800 2PE0473146 460 1 N A 2 2 2 8 5 2PE0473158 575 1 1050 1 5 1 9 4 Belt drive blower systems MUST...

Page 30: ... 1 Drill two 5 16 inch holes one in the return air duct as close to the inlet of the unit as possible and another in the supply air duct as close to the outlet of the unit as possible 2 Insert eight inches of 1 4 inch metal tubing into the air flow of both return and supply air ducts of the unit NOTE The tubes must be inserted and held in position per pendicular to the airflow so that velocity pre...

Page 31: ...increase Original Amps New Amps FIGURE 25 DRY COIL DELTA P DW 12 Units Indoor Coil Pressure Drop vs Airflow 0 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 1 3500 4000 4500 5000 5500 6000 6500 Airflow CFM Dry Coil Delta P IWG Before making any blower speed changes review the installation for any installation errors leaks or undesirable systems effects that can result in loss of airflow Even small changes in...

Page 32: ...ed with the operation When energized the indoor blower has a minimum run time of 30 seconds Additionally the indoor blower has a delay of 10 seconds between operations TABLE 21 ADDITIONAL STATIC RESISTANCE CFM Cooling Only1 Economizer2 3 Electric Heat KW2 18 24 36 54 3700 0 20 0 04 0 18 0 21 0 22 0 26 3900 0 23 0 04 0 20 0 23 0 24 0 28 4100 0 25 0 04 0 22 0 25 0 26 0 31 4300 0 28 0 05 0 24 0 28 0 ...

Page 33: ...ow voltage control circuit from R to Y2 is completed The UCB energizes the first available compressor If the enthalpy of the outdoor air is below the set point of the enthalpy controller i e first stage has energized the economizer Y2 will ener gize compressor 1 If the outdoor air is above the set point Y2 will energize compressor 2 Once the thermostat has been satisfied it will de energize Y1 and...

Page 34: ...ation The defrost cycle will begin immedi ately following the elapse of the minimum run time When operating in low ambient mode the UCB will not lock out the compressors due to a freezestat trip However a freezestat trip will de energize the associated compressor If the call for cooling is still present at the end of the ASCD and the freezestat has closed the unit will resume operation SAFETY CONT...

Page 35: ...gh of a setting will result in longer heat cycles and a greater temperature swing in the conditioned space Reducing the value below the correct setpoint will give shorter ON cycles and may result in the lowering of the temperature within the conditioned space Refer to Table 24 for the required electric heat anticipator setting GAS HEATING SEQUENCE OF OPERATIONS When the thermostat calls for the fi...

Page 36: ...r motor and flash code is initiated See Table 29 FLAME SENSE Flame sensing occurs at all times If W1 is not present and a flame is sensed for 2 seconds the draft motor is energized and the main valve is kept off The ICB halts any operation until a flame is not detected Once the flame detection is lost the ICB performs a post purge Normal operation is allowed concurrently with the purge i e this pu...

Page 37: ... the appropriate code See Table 31 Ignition Control Flash Codes The draft motor is energized until the pressure switch closes or W1 is lost ROLLOUT SWITCH ROS The rollout switch is wired in series with the pressure switch As such the ICB cannot distinguish the rollout switch opera tion from that of the pressure switch Consequently the control will only respond in the same man ner as outlined above...

Page 38: ...bustion air inlet are free of any debris or obstruction OPERATING INSTRUCTIONS LIGHTING THE MAIN BURNERS 1 Turn OFF electric power to unit 2 Turn room thermostat to lowest setting 3 Turn gas valve counter clockwise to ON position see Figure 27 4 Turn ON electric power to unit 5 If thermostat set temperature is above room tempera ture the main burners will ignite If a second stage of heat is called...

Page 39: ...L GAS This unit has two stages of gas heat The first stage is 60 of the full fire input and is considered the minimum input for the furnace The intended input for each furnace is shown in the table below The following Table applies to units operating on 60 Hz power only To determine the rate of gas flow second Stage 1 Turn of all other gas appliances connected to the gas meter 2 Turn on the furnac...

Page 40: ... decrease the blower CFM to increase the rise See SUPPLY AIR DRIVE ADJUSTMENT NOTE Each gas heat exchanger size has a minimum allowable CFM Below this CFM the limit will open below this rating BURNERS ORIFICES INSPECTION SERVICING Before checking or changing burners pilot or orifices CLOSE MAIN MANUAL SHUT OFF VALVE AND SHUT OFF ALL POWER TO THE UNIT 1 Open the union fitting just upstream of the u...

Page 41: ...r and dan gerous operation which could cause injury to person and or damage unit components Verify proper oper ation after servicing Troubleshooting of components may require open ing the electrical control box with the power con nected to the unit Use extreme care when working with live circuits Check the unit name plate for the correct line voltage and set the voltme ter to the correct range bef...

Page 42: ...s it may be necessary to zero the ASCD for the compressors in order to perform troubleshooting To reset all ASCDs for one cycle press and release the UCB TEST RESET button once Flash codes that do and do not represent alarms are listed in Table 29 TABLE 29 UNIT CONTROL BOARD FLASH CODES FLASH CODE DESCRIPTION GREEN LED 16 RED LED 8 RED LED 4 RED LED 2 RED LED 1 On Steady This is a Control Failure ...

Page 43: ...meters for the currently displayed mode Option Byte or Heat Delay HEAT DELAY SETUP Enter the Option Setup mode by pushing the OPTION SETUP STORE button and holding it for at least 2 sec onds The green status LED Option Byte will be turned on and the red status LED Heat Delay is turned off Press the COMM SETUP SELECT button to toggle into the Heat Delay Setup the green LED will turn off and the red...

Page 44: ...Off 0 10 Off Off Off On Non std Non std Off Off Off Off TABLE 31 IGNITION CONTROL FLASH CODES FLASHES FAULT CONDITIONS CHECK STEADY ON Control Failure Control HEARTBEAT Normal Operation 1 Not Applicable 2 Pressure Switch Stuck Closed Pressure Switch 3 Pressure Switch Failed To Close Venter Pressure Switch Vent Blocked 4 Limit Switch Open Main Limit AUX Limit 5 Flame Present With Gas Off First Stag...

Page 45: ...Cooling Yes Yes Loss of Call for Heating Loss of Call for Cooling Heat Off Cool Off Yes Yes No Call for ID Blower Fan off 10 secs Energize ID Blower Motor Yes Yes No Programming Program Unit Control Board Trip Failure No No Lossof Call for ID Blower Turn off ID Blower Motor Fan on 30 secs Yes No Yes No No Yes Yes No FIGURE 31 POWER ON FLOW CHART Power to Unit Initialize ASCD Call for heat Voltage ...

Page 46: ... s f l a g a l a r m C a l l f o r H e a t w o u t G V v o l t a g e N o v o l t a g e 5 m i n F l a g A l a r m F O S i n p u t r e g a i n e d I n c r e a s e i n c i d e n t v a l u e b y 1 N o F O S i n p u t 1 5 m i n u t e s F l a g a l a r m t u r n o n X l i n e G V v o l t a g e w o u t c a l l f o r h e a t G V v o l t a g e 5 m i n F l a g a l a r m l o c k o n I D b l o w e r L o s s o...

Page 47: ...not the room thermostat fan switch is in the AUTO position 1 If installed check the position of the economizer blades If the blades are open the economizer is providing free cooling and the compressors will not immediately oper ate If both stages of cooling are requested simultane ously and the economizer provides free cooling following a short delay compressor 1 will be energized unless it is loc...

Page 48: ...nged by the local distributor 15 If none of the above corrected the error test the integrity of the UCB Disconnect the C1 terminal wire and jumper it to the Y1 terminal DO NOT jump the Y1 to C1 termi nals If the compressor engages the UCB has faulted 16 If none of the above correct the error replace the UCB On calls for the second stage of cooling the supply air blower motor and compressor 1 are o...

Page 49: ...ousing If it is hot the compres sor may be off on inherent protection Cancel any calls for cooling and wait for the internal overload to reset Test again when cool 4 If M1 is not pulled in check for 24 volts at the M1 coil If 24 volts is present and M1 is not pulled in replace the contactor 5 Failing the above if voltage is supplied at M1 M1 is pulled in and the compressor still does not operate r...

Page 50: ... air blower motor energizes go to Step 10 2 If the supply air blower motor does not energize when the fan switch is set to ON check that line voltage is being supplied to the contacts of the M3 contactor and that the contactor is pulled in Check for loose wiring between the contactor and the supply air blower motor 3 If M3 is pulled in and voltage is supplied at M3 lightly touch the supply air blo...

Page 51: ...erminal from the pressure switch If present go to step 4 If 24 volts is not present the either pressure or rollout switch is not closed Or the draft motor is not sufficiently evacuating the heat exchanger tubes or the pressure switch has failed Check the operation of the pressure switch Check the line voltage to the unit if line voltage is low call the local power company If the problem persists t...

Page 52: ...o change without notice Printed in U S A 66389 BIM C 1208 Copyright 2009 by Johnson Controls Inc All rights reserved Supersedes 66389 BIM B 0606 Johnson Controls Unitary Products 5005 York Drive Norman OK 73069 ...

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