Lang GCCO-T Service Manual page 48

PROBABLE CAUSE
No Spark observed
Igniter continues to spark
after pilot is lit
Defective thermostat
Defective over-temp
thermostat
Defective Centrifugal switch
TROUBLESHOOTING GCCO-C CONT'D
CORRECTIVE ACTION
Turn oven on. Refer to wiring diagram and check for 24 VAC at the TH
terminal on the spark module.
If 24 VAC is measured, Turn unit off and:
Check large orange wire from igniter module to pilot burner for
continuity, and for insulation breaks.
Replace wire as necessary.
Check spark electrode and hood of pilot burner.
Check spark gap. Clean and re-gap if necessary.
Check pilot burner for any evidence of moisture. Dry pilot if
necessary.
Replace spark module if above checks do not correct problem.
If 24 VAC is not measured, Turn oven off and:
Check 120/24 VAC transformer of 18.9 Ω on the primary coil and 1
Ω on the secondary coil.
Turn unit back on and check primary coil for 120 VAC and secondary
for 24 VAC.
Replace if necessary.
Check pilot for strong flame and good contact with sensor.
Check sense wire for 12 to 13 amps on spark module. (Johnson
Control spark modules use "4" terminal and Channel spark modules
use "sense" terminal).
Turn oven off and check sense wire for continuity.
Replace sense wire or spark module as necessary.
Turn unit off and check for continuity while cycling thermostat on
and off.
Replace if defective.
Check for 24 VAC on wire # 55 on MV of spark module to ground.
If 24 VAC is not measured, Turn oven off and:
Check for continuity through over-temp thermostat.
Replace if defective.
If 24 VAC is measured, Turn oven off and:
Check for continuity on the gas solenoid valve.
Replace if defective.
Check for 24 VAC on wire # 55 on MV of spark module to ground.
If 24 VAC is not measured:
Check for 24 VAC on red wire coming out of motor to ground.
Replace if defective.
NOTE: You can check for continuity through Centrifugal switch by
turning thermostat off wile oven is still on.
If 24 VAC is measured, Turn oven off and:
Check for continuity on the gas solenoid valve.
Replace if defective.
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