Lang GCCO-C, Service Manual

Page: 39 / 73

39
TROUBLESHOOTING GCCO-AP
NO MOTOR
PROBABLE CAUSE CORRECTIVE ACTION
Defective power switch Check power switch for normal operation. Replace as necessary.
Defective Transformer Check Transformer for normal operation.
Gas supply turned off Turn gas supply on and check for proper gas pressure. 5” water
column for natural gas and 10” water column for propane.
Defective Pilot Perform the following “trial ignition” and look and listen for spark:
Attempt to light the pilot burner. If the burner does not ignite
after 30 seconds, cycle power and repeat “trial ignition”. The
pilot may require several trials for ignition to bleed air from the
gas piping. After the ignition attempt, pilot should only require
2-5 seconds for normal start-up.
Spark observed Check for 24 VAC at pilot valve.
If 24 VAC is measured , turn oven off:
Check for pilot burner orifice blockage. Clean and repair as
necessary.
Perform trial ignition, as described in above section.
Replace gas valve.
If 24 VAC is not measured:
Check for 24 VAC at PV on spark module.
Check continuity on wire between PV on spark module and Pilot
Valve.
No spark observed 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 oven off:
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:
Check 120/24 VAC transformer for 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 transformer.