Test Procedures
Compressor contactor
1. Test using the controller’s indicator lights. When
the unit is in ice making mode the compressor
contactor will have power. Check the Compressor
indicator light, when it is on the compressor
contactor will have pulled in. If it is not, do a voltage
check. Place voltmeter leads on the coil of the
contactor. There should be full voltage . If there is
full voltage present and the contactor has not
pulled in, replace the contactor. If there is no
voltage check if the high pressure cut out is open. If
the high pressure cut out is closed, check for
voltage from the controller to ground. The contactor
pin is 4. Check from 4 to ground when the
compressor indicator light is on. There should be
voltage. If not, replace the controller. If there is
voltage at the controller but not at the contactor
coil, the harness wires or connectors are damaged
and must be replaced.
2. Test using an ohmmeter. Disconnect electrical
power.
Test the coil of the contactor for continuity or shorts
to ground. Replace if open or shorted.
3. Check connections and contacts. Be sure
connections are tight and that the contacts are not
burnt. Replace any contactor with burnt contacts.
Pressure switches
There are two pressure switches: Fan and High
Pressure cut out.
Fan. The fan pressure switch will open to shut the
fan motor off at a certain pressure and re-close at a
preset higher pressure.
High pressure cut out. The high pressure cut out
switch will open at a preset pressure, shutting off
power to the compressor contactor. After the
pressure has fallen to another preset level, the
switch will re-close and the contactor coil will be
energized.
To Test Fan Pressure Switch:
A. Attach refrigeration gauge set to high side port.
B. Unplug both wires from fan pressure control.
Be
SURE the wire's terminals are wrapped in
electrical tape to prevent short circuits to
ground during the test.
C. Connect ohmmeter to terminals of fan pressure
control..
D. Switch ice machine on, observe pressure that
the pressure control closes at, compare to spec.
Switch unit off, allow system to equalize, observe
pressure the pressure control opens at, compare to
spec.
To Test High Pressure Switch:
A. Attach refrigeration gauge set to high side port.
B. Unplug fan motor or shut water off if water
cooled.
C. Measure voltage between contactor side
terminal of high pressure control and ground.
D. Switch ice machine on, observe pressure that
the pressure control opens at, compare to spec.
Allow system to equalize, observe the pressure
that the pressure control closes at, compare to
spec.
Transformer
Check secondary voltage, it must be between 10
and 15.5 AC volts. Replace if no voltage is output
or if above or below the acceptable voltage..
May 2008
Page 39
CU1526, CU2026, CU3030
Service Manual
Electrical Shock
Hazard
.
Disconnect electrical
power before
beginning diagnostic
procedure.
