– 50 –
Heavy Frost on Evaporator
Always check for door ajar,
customer usage, numerous
door openings, etc.
Perform self-diagnostic test 1-4
(touch panel models only,
rotary models proceed
to step below).
Did unit initiate defrost?
Unplug unit from power.
Unplug blue connector from
main board. Measure
between blue wire on
connector and neutral orange
wire on main board J7-9.
Are there approximately 22
?
Check wiring harness.
Check defrost heater.
Check defrost thermostat.
Check evaporator
thermistor value.
Value OK?
YES
Check wiring connections. If
wiring OK, replace thermistor.
NO
Replace main
board.
YES
NO
NO
YES
With doors open
check for voltage at
J7-6 to J7-9 and J7-7
to J7-9.
Voltage present?
Replace main
board.
YES
Bad door switch or
wiring. Repair as
necessary.
NO