Service Guide
32
C. Control Module Check
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, conrm there is a good power supply and neutral
connection to CM: 115VAC at CM L2 (BK) to CM N3 (W).
Alarm Reset: To silence the alarm, press and release the up button with power on.
Foralarm information, see "III.D. Alarm Safeties."
2. Startup/Cool Down
1) Check all wiring connections. Conrm the CTh and DTh are properly connected.
2) Move the power switch to the "ON" position.
3) Check for 115VAC at CM L2 (BK) to CM N3 neutral (W). If 115VAC is not present, check
power supply, wire connections, and power switch.
4) Check that cabinet temperature is displayed. If not, replace CM.
5) Check that EvapFM is energized from CM F5 (Y or W/BU) (except refrigerator F-6 and
earlier). Make sure doors are closed and DS engaged. Next, check for 115VAC at CM
F5 (Y or W/BU) to neutral (W). If 115VAC is not present, replace CM.
6) Check that Comp and ConFM energize (MH and PH on Freezer F-8 and later). If not,
check CTh status. See "II.D.Thermistor Check." If CTh ohm reading is in proper range,
check for 115VAC at CM C1 (R or V) to neutral (W). If 115VAC is not present, replace
CM.
3. Defrost Initiation
7) Manual Defrost Check: Press the manual defrost button briey. If on, Comp and
EvapFM (except refrigerator F-6 and earlier) icons turn off. Defrosticon turns on and
"dEF" is displayed.
8) Conrm Comp, ConFM, EvapFM (F-7 and later and freezers), MH, and PH (freezers F-8
and later) de-energize (EvapFM continues on refrigerator F-6 and earlier). Check for
115VAC at CM C1 (R or V) to neutral (W) for Comp, ConFM, and MH, and PH (freezers
F-8 and later) then at CM F5 (Y or W/BU) to neutral (W) for EvapFM (refrigerator F-7
and later and freezers). If"dEF" is displayed and 115VAC is present, replace CM.
9) Freezers: Conrm DH energizes. Check for 115VAC at CM H4 (O) to neutral (W).
If"dEF" is displayed and 115VAC is not present, replace CM.