GE PSC21MGM, Technical Service Manual

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Heavy Frost on Evaporator
Run Service Diagnostic Test (1-4)
Defrost system check
Does defrost heater come on?
Carefully unplug J9 blue connector from
main board. Measure between blue wire on
connector and neutral orange wire on main
board J7. Is there approximately 27
Ω
?
No
Check for 120 VAC from
neutral orange wire J7 to
defrost terminal J9 on main
board.
Is 120 VAC present?
Yes
Run Service Diagnostic Test (0-7)
for thermistors
Do thermistors pass test?
Check door ajar
Customer usage -
numerous door openings
Yes
Repair wiring connections
or
replace thermistor
No
No
Replace
main board
Yes
Check wiring harness
Check defrost heater
Check defrost thermostat
Reinstall blue connector
Measure for 120VAC
at defrost heater.
Is 120VAC present?
Check wiring
between heater
and main board
No
Yes
Replace
defrost
heater
Yes
No
Caution: Unplug power when disconnecting and
connecting connectors on the board.