Lang GCCO-T Service Manual page 46

NO FAN-Manual Mode
PROBABLE CAUSE
Defective 120/24 VAC
transformer
Back-up relay not energizing
Motor contactor not
energized
No voltage across contactor
points
Defective motor
Note: Motor should now be operating.
TROUBLESHOOTING GCCO-C CONT'D
CORRECTIVE ACTION
Check for 24 VAC on "C" and "D" of the terminal block.
If 24 VAC is not measured: Turn off and:
Check secondary coil for 1 Ω.
Check primary coil for 18.9 Ω.
Replace transformer.
If 24 VAC is measured: Turn off and:
Check back-up relay for normal operation.
Check for 24 VAC on relay coil.
If 240 VAC is measured: Turn unit off and:
Check back-up relay coil for 80 Ω.
Replace if defective.
If 240 VAC is not measured:
Check back-up switch (SPDT) for normal operation.
Replace if defective.
Check for 24 VAC at contactor or relay coil.
If 24 VAC is not measured: Turn oven off and:
Check door switch for normal operation.
Check door switch for continuity.
Replace or adjust door switch.
If 24 VAC is measured: Turn unit off and:
Check contactor coil for continuity.
Replace if defective.
Check 120 VAC across "C" terminals of contactor.
If 120 VAC is not measured:
Check connection to main contactor (heat contactor).
If 208/240 VAC is measured:
Check across "NO" contacts. Should have 120 VAC.
Replace if defective.
Check for 120 VAC at motor.
If 120 VAC is measured, Turn oven off:
Check motor winding's for continuity.
Replace if defective.
If120 VAC is not measured:
Check wiring between motor and contactor.
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