Service Manual

16
1. Control Module Display. Before replacing CM that does not show a visible defect and that
you suspect is bad, conduct the following check procedure. This procedure will help you
verify your diagnosis. Always choose a neutral (W) to establish a good neutral connection
when checking high voltages. Also, conrm there is a good power supply and neutral
connection to CM: 115VAC.
2. Startup/Cool Down.
3. Check all wiring connections. Conrm the CTh is properly connected.
4. Check for 115VAC to neutral. If 115VAC is not present, check power supply, and wire
connections.
5. Make sure doors are closed. Next, check for 115VAC to neutral. If 115VAC is not present,
replace CM.
6. Check that Comp and ConFM energize. If not, check CTh status. See “II.D. Thermistor
Check.” If CTh ohm reading is in proper range, check for 115VAC at CM to neutral.
If 115VAC is not present, replace CM.
7. Defrost Initiation. Defrost initiation by 4 hours compressor cumulative run time. Conrm
Comp and ConFM de-energize, EvapFM continues on. Check for 115VAC at CM to neutral
for Comp and ConFM, then at CM to neutral for EvapFM.
8. Defrost Termination. Check after a 25 min. that the Comp turn on again.
Legend: CM–control module; Comp–compressor; ConFM–condenser fan motor; CTh–cabinet
thermistor; DS–door switch; DTh–defrost thermistor; EvapFM–evaporator fan motors,
MH–mullion heater; PH–perimeter heater.
C. Control Module Check