Service Manual for Models CU0415, CU0715 and CU0920
August 2013
Page 20
Controller Self Test
Control Board Self-Test Routine. Begin with unit
unplugged and no ice touching the bin control.
1. Remove top and back panels to access thermistor
on suction line (above accumulator).
2. Remove the thermistor probe from the suction
line.
3. Shut water supply off.
4. Remove front panel to access control.
5. Place evaporator thermistor probe in ice water, ice
water temperature should be 0 C or 32 F.
6. Plug unit in, master switch in the ON position.
5 minutes or more after the freeze cycle starts
check reservoir water temperature. When it and
the evaporator thermistor’s ice water are at 32 F,
hold BOTH upper left - button and lower right +
button in for at least 5 seconds, then release the
buttons.
7. The green level LEDs will turn off and the yellow
Timer LED will turn on for two seconds once you
have entered the test mode.
8. Press upper left - button and the evaporator
thermistor temperature test will begin. The
yellow Timer LED will turn on for 2 seconds if the
evaporator thermistor temperature is 32 F +/- 2
degrees.
9. Press upper left - again and the sump thermistor
temperature test will begin. The yellow Timer LED
will turn on for 2 seconds if the sump thermistor
temperature is 32 F +/- 2 degrees. Note:
Pressing - repeatedly will toggle between testing
the two thermistor temperatures.
10. Press upper right + button and the Freeze relay
will close and the blue Freeze LED will turn on for
5 seconds. Compressor, fan motor and pump will
start. If not, the controller has failed.
11. Press upper right + again and the Pump relay will
switch, the pump will stop and red LED (on back
side of the board) will turn on for 5 seconds. Note:
Pr repeatedly will toggle between testing
the two relays.
12. Press and hold lower left - button and it will turn
on each of the green LEDs, one at a time. Hold
lower left – button in until all of the green LEDs
are tested.
13. Press lower right + button to test the EEPROM
read and write. The yellow Timer LED will turn
on for 2 seconds if the EEPROM read and write
operations were successful.
Power down the board to exit the test mode.
Test Results:
Step
Pass
Fail
Action if Failed
8
Yellow Timer LED
switches ON
No timer
light
Replace
thermistor set
9
Yellow Timer LED
switches ON
No timer
light
Replace
thermistor set
10
Compressor, fan
motor and pump
start
Either
compressor
or pump do
not start
Check voltage
to compressor
or pump, If
no voltage
to one or
both, replace
controller.
11
Water pump
stops
Pump does
not stop
Replace
controller
12
All green LEDs
light up
Some do not
illuminate
Replace
controller
13
Yellow Timer LED
switches ON
No timer
light
Replace
controller
If the controller passes all tests, there is nothing
wrong with it and the issue is in something else.
1. Reattach evaporator thermistor to the suction line
at the same place it was mounted and re-insulate
it.
2. Reconnect water supply, restart unit and return all
panels to their original positions.
September 2014
