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10) Shutdown – See "IV.D. Bin Control Check."
Legend: CB–control board; Comp–compressor; DV–drain valve; EHH–extruding
head heater (-C model only); FM–fan motor; FMR–fan motor-remote;
GM–gear motor; GMPR–gear motor protect relay; GMR–gear motor
relay; IS–infrared sensor; LF/S–lower oat switch; LLV–liquid line
valve (MLH model only);
MBC–mechanical bin control; SLV–suction line
valve (MLH model only); UF/S–upper oat switch; WV–inlet water valve
C. Control Board Check
Before replacing a control board 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.
1) Check the S1 dip switch settings to assure that they are in the factory default position.
S1 dip switch 7 is determined by bin control application:
Bin Control Application:
Infrared Sensor Bin Control: S1 dip switch 7 in the "OFF" position.
Mechanical Bin Control: S1 dip switch 7 in the "ON" position.
For factory default settings, see "II.C.4.a) Default Dip Switch Settings."
) Move the power switch to the "ON" position and move the control switch to the "ICE"
position. The "POWER OK" LED turns on. Diagnosis "POWER OK" LED: Check that
the "POWER OK" LED is on. If not, check for proper supply voltage (115VAC) input to
the control transformer (power switch, breaker, fuse, and circuit protect relay). Next,
check for proper low-voltage (4VAC) output from the control transformer and that
the 1A fuse is good. Check for 4VAC from K8 connector pin #1 white/red (W/R) to
K8 connector pin # light blue (LBU). If 4VAC is present and the "POWER OK" LED is
off, the control board is bad and must be replaced.
3) "WTRIN" LED is on: When the lower or upper oat switch is open, the inlet water valve
energizes and water lls the reservoir. Diagnosis: If "WTRIN" LED is off, upper oat
switch is closed (reservoir full), "GM" LED is on, and the gear motor energizes, skip
to step 8. If "WTRIN" and "GM" LED are off, conrm that the control switch is in the
"ICE" position (open). Check that the yellow LED on the infrared sensor is not steady
or ashing (see step 4 below). Next, check the continuity of the lower and upper oat
switches (open or closed). For further details, see 5.f. below. If the lower or upper
oat switch is open and the "WTRIN" LED is off, the control board is bad and must be
replaced. If the "WTRIN" LED is on and the lower or upper oat switch is open, water
should be lling the reservoir. If not, skip to step 6.