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B. Control Board Check
Before replacing a CB that does not show a visible defect and that you suspect is bad,
always conduct the following check procedure. This procedure will help you verify your
diagnosis. Always choose a neutral (W wire) to establish a good neutral connection
when checking AC voltage (115VAC).
Startup and Cool Down:
1) Press the power button for 2 sec. to turn off the appliance.
2) Unplug the appliance from the electrical outlet.
3) Remove the top panel. Check all wiring connections. Conrm that the power cord,
EvapFM, Comp, DS, and CTh are all properly connected to CB and ground connection
(GND) is properly connected to the frame.
4) Secure the top panel to prevent it from falling over when checking voltages and
CBitems.
5) Secure (tape) DS in the door closed position.
6) Plug the appliance back in. °F LED turns on. Diagnosis: Conrm that °F LED is on. If
not, check CB POWER connector for 115VAC. If 115VAC is not present, check power
supply and power cord connection. If 115VAC is present and °FLED is not on, replace
CB.
7) Press the power button for 2 sec. to turn on the appliance.
8) Check that
CT LEDs and EvapFM icon turn on. If not, check for 115VAC at the POWER
connector on CB. If 115VAC is not present, check power cord and power supply.
If115VAC is present, and DM is not on (°F and CT LEDs and EvapFM icon), replace
CB.
9) If
°F and CT LEDs are on but EvapFM icon is not, conrm DS is engaged (pushed in,
contacts open). Check across DS for 5VDC. If 5VDC is not present, check DS activation
lever and DS continuity. Note: DS contacts are open when DS is engaged (door closed).
If 5VDC is present, check CB EvapFM connector for 12VDC. If 12VDC is not present,
replace CB. If 12VDC is present, check EvapFM wiring connector for loose connection,
EvapFM continuity, and fan blade for binding.
10) Defrost:
This appliance defrosts every 6 hrs. for 30 min. Defrost is an off-cycle defrost.
a) Manual Defrost Initiation: To initiate a manual defrost, press and hold the "+" button
until the defrost icon turns on. 30-min.DTstarts. EvapFM continues. If Comp run
time < 3 min., Comp icon and Comp continue until 3-min. Comp run timer terminates.
Once 3-min. Comp run timer terminates, Comp icon turns off, Comp de-energizes,
and 30-min. DT starts. Diagnosis: If defrost icon is on, conrm that Comp
de-energizes. If not, conrm Comp run time > 3min. If Comp continues after 3-min.
Comp run timer terminates, replace CB.