Heater Will Not Fire - C
Start
Is “SERVICE HEATER” LED |
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“on”? |
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| Turn off 120 VAC |
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| YES |
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| power to heater for 5 |
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| seconds, and turn |
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| back on. |
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| Make sure tempera- |
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If any red diagnostic LED’s |
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| ture setting is above | YES | ||||||
(AGS, AFS, SFS, HLS, PS, or |
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THERMISTOR) come “on”, go |
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| Wait one minute. |
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to Pages 28 and 29. |
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| Does heater fire and |
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| CONTINUE |
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| stay on? |
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| NO |
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Did burner fire at all? |
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| Did Blower come on? |
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| YES |
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| YES | NO |
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Go to “BURNER |
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| Verify that gas is flow- |
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| ing to burner during |
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TROUBLESHOOTING” |
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| ignition try. Observe |
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(Page 30) |
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| gas meter for move- |
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| ment during ignition |
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Go to “HEATER WILL NOT |
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| try (wait for about 30 |
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| seconds after calling |
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| for heat). |
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Go to “INITIAL TROUBLESHOOTING”
Continue to observe heater for several minutes. Cycle heater on and off several times. Observe for delayed or rough ignition, poor combus- tion, premature extinction of flame, evidence of boiling, or operation of any diagnostic LED. Go to pertinent trou- bleshooting section if any malfunction is observed.
Replace Control Board.
Verify that gas supply is open all the way to Gas Valve, and Gas Valve knob is at “on” position.
Check for 24 VAC to Gas Valve terminals during ignition try. (Voltage appears about 24 seconds after call for heat). SEE NOTE 1.
Replace Ignition Control Module.
NO
Check for 24 VAC between VAL and GND terminals on Ignition Control Module.
SEE NOTE 1.
YES
Check for 24 VAC between VAL and GND terminals on Control Board. SEE NOTE 1.
NO
Fix wiring between VAL and GND terminals of Ignition Control Module and Control Board.
YES
YES
Check for 24 VAC between TH and GND terminals on Ignition Control Module.
SEE NOTE 2.
NO | YES | |
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Check for 24 VAC |
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between TH and GND | NO | |
terminals on Control | ||
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Board. SEE NOTE 2. |
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Check for 24 VAC | YES | ||
between GAS termi- | |||
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nals on Control |
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Board. SEE NOTE 1. |
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NO
Replace Control
Board.
YES
Replace Gas Valve with identical part.
Fix wiring between TH and GND terminals of Ignition Control Module and Control Board.
Replace Control Board.
Fix wiring between GAS ter- minals on Control Board and Gas Valve.
NOTE 1: Voltage appears about 24 seconds after call for heat, and may be on for only about 7 seconds.
NOTE 2: Voltage appears immedi- ately after call for heat, and may be on for only about 30 seconds.
26
