COMFORT-AIRE Century GUH80C045A3M Service Manual Download | Manualshive

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508096-01

Issue 2037

Page

5

of 3

1

Figure 1.

Control Box

(includes integrated control,

interlock switch and transformer)

Gas Valve

Burner Box

(includes sensor, ignitor

and rollout switches)

Combustion Air Inducer

Combustion Air Inducer

Pressure Switch

Heat Exchanger

Upper Access Panel

Blower Access Panel

Primary Limit

(under

combustion

air inducer)

Make-Up Box

Blower Assembly

Power Choke

(4 and 5 Ton Only)

Parts Arrangement

«
...
3
4
5
6
7
...
»

Summary of Contents for Century GUH80C045A3M

Page 1: ... be ignored When you see this symbol on labels or in manuals be alert to the potential for personal injury or death Electric shock hazard Can cause injury or death Before attempting to perform any service or maintenance turn the electrical power to unit OFF at disconnect switch es Unit may have multiple power supplies WARNING As with any mechanical equipment contact with sharp sheet metal edges ca...

Page 2: ...0 2 1 2 4 1 2 120 60 1 15 8 4 40 142 GUH80C090C5M 88 000 70 400 80 0 3 5 1 2 120 60 1 15 10 9 40 152 GUH80C110C5M 110 000 88 000 80 0 4 5 1 2 120 60 1 15 10 9 40 160 GUH80C135D5M 132 000 105 600 80 0 4 5 1 2 120 60 1 15 10 9 40 178 Note For vent sizing and clearances to combustibles please reference installation instructions REV CODE REVISION NOM CFM X 100 2 TON ADD ON COOLING 3 TON ADD ON COOLING...

Page 3: ...Low 885 825 770 695 625 540 445 GUH80C090B4M 3 4 10 x 10 35 65 High 1730 1690 1645 1615 1590 1545 N A Med High 1505 1460 1435 1395 1350 1300 1270 Med 1380 1345 1310 1265 1210 1175 1140 Med Low 1310 1275 1240 1180 1150 1095 1040 Low 1110 1065 1010 955 915 860 820 GUH80C090C5M 1 11 1 2 x 10 30 60 High 2150 2125 2090 2060 2020 1980 1935 Med High 1865 1835 1800 1760 1725 1680 1635 Med 1655 1635 1585 1...

Page 4: ...8W63 21 0 C Width 86W57 24 5 D Width Downflow Combustible Flooring Base 11M59 14 5 A Width 11M60 17 5 B Width 11M61 21 0 C Width Night Service Kits 86W57 Single Stage Horizontal Suspension Kits 51W10 80 90 Kit 2 Stage Compressor Relay Kit 85W66 Blower Relay Kit Twinning kit 16W72 Constant Torque Gas Furnace Twinning Kit Note For vent sizing and clearances to combustibles please reference installat...

Page 5: ...nsformer Gas Valve Burner Box includes sensor ignitor and rollout switches Combustion Air Inducer Combustion Air Inducer Pressure Switch Heat Exchanger Upper Access Panel Blower Access Panel Primary Limit under combustion air inducer Make Up Box Blower Assembly Power Choke 4 and 5 Ton Only Parts Arrangement ...

Page 6: ...ovides overcurrent protection to the transformer T1 The breaker is rated at 3A at 32V If the current exceeds this limit the breaker will trip and all unit operation will shutdown The breaker can be manually reset by pressing the button on the face Integrated Ignition Control Shock hazard Disconnect power before servicing Control is not field repairable If control is inoperable simply replace entir...

Page 7: ...g heat demand 4 Low Flame Signal check flame sensor 5 Watchguard burner failed to light exceeded maximum number of retries or recycles 6 Not Used 7 Primary or Secondary Limit Open or Watchguard Mode Limit Switch Open longer than 3 minutes 8 Rollout Switch Open 9 Pressure Switch failed to close or opened during heat demand 10 Watchguard Pressure Switch opened 5 times during one heat demand 11 Press...

Page 8: ... Open 9 Pressure Switch failed to close or opened during heat demand 10 Watchguard Pressure Switch opened 5 times during one heat demand 11 Pressure Switch stuck closed prior to activation of combustion air inducer 12 Flame Sensed without gas valve energized 13 Low Line Voltage 1 A Heartbeat is indicated by a Slow Flash 1 sec on 1 sec off repeating 2 Error codes are indicated by a Rapid Flash the ...

Page 9: ...arm up time between trials of 35 seconds After a total of five trials for ignition including the initial trial the integrated control goes into Watchguard Flame Failure mode After a 60 minute reset period the integrated control will begin the ignition sequence again Fan Time Control Heating Fan On Time The fan on time of 30 seconds is not adjustable Heating Fan Off Time Fan off time time that the ...

Page 10: ...47 is a high temperature limit Each furnace is equipped with two identical switches The limit is a N C SPST manual reset limit connected in series with the integrated control A92 When S47 senses rollout the integrated control immediately stops ignition and closes the gas valve If unit is running and flame rollout is detected the gas valve will close and integrated control will be disabled Rollout ...

Page 11: ...r Combustion Air Inducer Primary Limit Gas Valve Figure 6 The GUH80C uses an internally redundant valve to assure safety shut off If the gas valve must be replaced the same type valve must be used 24VAC terminals and valve switch are located on the valve All terminals on the gas valve are connected to wires from the integrated control 24V applied to the terminals energizes the valve Inlet and outl...

Page 12: ... Sensor Wire from Integrated Control and Connect Alligator Clip to Flame Sensor Lead Flame Sensor Terminal Remove Sensor Wire from Integrated Control and Connect Alligator Clip to Terminal on Control DIGITAL METER To Control Sensor Terminal To flame sensor Set dial to measure dc microamps Red Collar Indicates Positive Lead ...

Page 13: ...robes into terminals 2 and 4 use small diameter probes in order not to damage plug Check voltage during 20 second ignitor warm up period Voltage should read 120 volts 10 If voltage reads below these values check for correct supply voltage to furnace Meter set to ohms Meter set to ohms Integrated Control Board Detail Meter set to ohms Test 1 Check ignitor circuit for correct resistance Remove 4 pin...

Page 14: ...is a single pole single throw proving switch electrically connected to the furnace control The purpose of the switch is to prevent burner operation if the combustion air inducer is not operating or if the flue becomes obstructed On start up the switch senses that the combustion air inducer is operating It closes a circuit to the integrated control when pressure inside the combustion air inducer de...

Page 15: ... air inducer then reinstall the mounting screws See unit Installation Instructions for more detail The combustion air pressure switch must be moved for horizontal discharge air left position IMPORTANT Figure 11 vent pipe vent pipe flue transition vent pipe FLOW AIR flue transition vent pipe pressure switch vent pipe In all positions route the wires away from moving parts and the heat of the induce...

Page 16: ...han 20mA Troubleshooting the Motor Troubleshooting the motor is an easy process Follow steps below 1 Shut off power to unit 2 Remove input plugs P48 and P49 from motor See Figure 14 for troubleshooting procedure If correct voltage is present in tests 1 and 2 and motor is not operating properly replace motor The motor is not field repairable If replacing the indoor blower motor or blower wheel is n...

Page 17: ...g P49 If 24 volts is not present problem may be up stream of plug P49 Proceed to test 4 Multi Meter set to VAC 12 0 12 0 24 Multi Meter set to VAC problem is with the harness If voltage is not present problem may be may be with the integrated control Check for 120 volts across terminals CIRC and Neutrals on the integrated control If voltage is present problem is with the harness If voltage is not ...

Page 18: ... 20 000 2 K two kilo ohms two thousand ohms 0 2 000 200 two hundred ohms 0 200 Motor Module Installation All replacement motor control modules look similar however each module is designed for a specific motor size It is very important to make sure that you are using the correct replacement motor control module USE OF THE WRONG MOTOR CONTROL MODULE MAY RESULT IN UNEXPECTED UNIT OPERATION 1 Verify e...

Page 19: ...h 11 may need to be repeated to purge air from gas line 12 If the appliance will not operate follow the instructions Turning Off Gas to Unit and call your service technician or gas supplier Turning Off Gas to Unit 1 Set the thermostat to the lowest setting 2 Turn off all electrical power to the unit if service is to be performed 3 Remove the upper access panel 4 Move gas valve switch to OFF positi...

Page 20: ... time in Table 8 If manifold pressure matches Table 10 and rate is incorrect check gas orifices for proper size and restriction Remove temporary gas meter if installed NOTE To obtain accurate reading shut off all other gas appliances connected to meter Capacity Seconds for One Revolution Natural LP 1 cu ft Dial 2 cu ft Dial 1 cu ft Dial 2 cu ft Dial 45 80 160 200 400 70 55 110 136 272 90 41 82 102...

Page 21: ... 5 LP Propane 10 0 10 0 9 6 10 0 11 0 110 Natural 3 5 3 5 3 0 3 5 4 5 LP Propane 10 0 10 0 9 6 10 0 11 0 135 Natural 3 5 3 5 2 9 3 5 4 5 LP Propane 10 0 10 0 9 6 10 0 11 0 NOTE A natural to LP propane gas changeover kit is necessary to convert this unit Refer to the changeover kit installation instruction for the conversion procedure Table 10 Manifold and Supply Line Pressure 0 10 000 ft Capacity ...

Page 22: ... indicates a poor or partial ground Compare the readings to Table 12 If the readings exceed the maximum shown in Table 12 make repairs before operating the furnace 2 In addition measure the AC voltage from Line Hot to Line Neutral spade terminals on the integrated control See Figure 19 This voltage should be in the range of 97 to 132 VAC Furnace Status Measurement VAC Expected Maximum Power On Fur...

Page 23: ...nd return air plenums Insert manometer hose flush with inside edge of hole or insulation Seal around the hose with permagum Connect the zero end of the manometer to the discharge supply side of the system On ducted systems connect the other end of manometer to the return duct as above 3 With only the blower motor running and the evaporator coil dry observe the manometer reading Adjust blower motor...

Page 24: ...d heat exchanger and clean if necessary 6 Check the cleanliness of blower assembly and clean the housing blower wheel and blower motor if necessary The blower motors are prelubricated for extended bearing life No further lubrication is needed 7 Inspect the combustion air inducer and clean if necessary 8 Evaluate the heat exchanger integrity by inspecting the heat exchanger per the AHRI heat exchan...

Page 25: ... Remove heat exchanger It may be necessary to spread cabinet side to allow more room If so remove five screws from the left side or right side of cabinet See Figure 23 10 Backwash using steam Begin from the burner opening on each clam Steam must not exceed 275 F 11 To clean burners run a vacuum cleaner with a soft brush attachment over the face of burners Visually inspect inside the burners and cr...

Page 26: ... of cabinet 1 2 3 4 5 Heat Exchanger Gasket Collector Box Orifice Plate Flue Transition Pressure Switch Combustion Air Inducer Manifold And Gas Valve Retention Rings Cross Over Ignitor Flame Sensor Rollout Switches Figure 24 Burner Combustion Air Inducer Assembly Heat Exchanger Removal ...

Page 27: ...508096 01 Issue 2037 Page 27 of 31 045 3 135 5 110 5 110 4 110 3 090 4 090 3 070 3 070 2 Wiring Diagram ...

Page 28: ...GIZED GAS VALVE OFF COMBUSTION AIR INDUCER ON INDOOR BLOWER ON HEATING SPEED LED FLASHES CODE 11 PRESSURE SWITCH CLOSED GAS VALVE OFF COMBUSTION AIR INDUCER OFF INDOOR BLOWER OFF WITH DELAY Sequence holds until pressure switch opens or thermostat resets control NO NO YES YES IS VOLTAGE ABOVE 70 VOLTS LED FLASHES CODE 13 LOW LINE VOLTAGE CONTROL WILL NOT RESPOND TO A CALL FOR HEATING UNTIL VOLTAGE ...

Page 29: ...FF WITH DELAY IS 60 MINUTE RESET PERIOD COMPLETE YES 4 SECONDS YES HAS CONTROL RESET IGNITION SEQUENCE FOUR TIMES FLAME SIGNAL 1 5 MICROAMPS OR GREATER YES YES YES ROLLOUT SWITCH CLOSED LED FLASHES CODE 8 ROLLOUT SWITCH OPEN GAS VALVE POWER OFF COMBUSTION AIR INDUCER POWER ON INDOOR BLOWER ON SEQUENCE HOLDS UNTIL ROLLOUT SWITCH IS RESET AND MAIN POWER IS INTERRUPTED OR THERMOSTAT IS CYCLED OFF ON ...

Page 30: ...ONITORED CONTINUOUSLY IS ROLLOUT SWITCH CLOSED LED SLOW FLASH RATE REMAINS UNCHANGED THROUGHOUT COOLING CYCLE THERMOSTAT CALLS FOR COOLING COMPRESSOR CONTACTOR AND SYSTEM FAN ENERGIZED WITH 2 SECOND DELAY COOLING SPEED COMPRESSOR OFF THERMOSTAT OPENS SYSTEM FAN AND EAC TERM OFF WITH 45 SECOND DELAY NO NO LED FLASHES CODE 8 ROLLOUT SWITCH OPEN GAS VALVE OFF COMBUSTION AIR INDUCER ON INDOOR BLOWER O...

Page 31: ...G THERMOSTAT OPENS SYSTEM FAN SWITCHED TO COOL SPEED EAC TERM REMAINS ON THERMOSTAT OPENS MANUAL FAN SELECTION MADE AT THERMOSTAT CONTROL G ENERGIZES SYSTEM FAN AT FAN SPEED EAC TERM ENERGIZED NO YES YES NO SYSTEM FAN SWITCHES TO HEAT SPEAD AFTER 30 SECOND DELAY EAC AND HUM TERMINALS REMAIN ON SYSTEM FAN CONTINUES FAN SPEED WITHOUT INTERRUPTION EAC TERMINAL REMAIN ON HUM TERMINALS ARE ENERGIZED WI...

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