Test Procedures - Sensors
All electrical components in this ice machine can be diagnosed with a volt-ohmmeter.
Curtain Switch:
1. Test using the controller’s indicator lights.
Observe SW1 or SW2. Open and close the curtain.
When the curtain is opened, the SW light will be
ON. When the curtain gets to within a half inch of
closing (at the switch) the SW light will go OUT.
2. Test with an ohmmeter. Disconnect electrical
power. Open the control box cover. Unplug the
curtain switch lead from the controller. Connect an
ohmmeter to the leads of the switch. Open and
close the curtain. When the curtain is closed, the
switch is closed and there will be continuity. When
the curtain is open, the switch is open and the
circuit will be open.
3. Test the controller’s curtain switch circuit by
jumping the connectors on J1 or J2 together.
Reconnect electrical power. When jumped, the
matching SW light will go out. When unplugged or
open, the SW light will be ON.
Ice Thickness Sensor
1. Test using the controller’s indicator light.
Observe the Ready To Harvest light. Shut the
machine off. Use a wire to connect the metal part
of the Ice Thickness sensor to the evaporator or
simply remove the Ice Thickness Sensor and touch
its metal surface to the metal control box wall. The
Ready for Harvest light should go ON.
2. Test with an Ohmmeter. Disconnect electrical
power. Open the control box cover. Unplug the ice
thickness sensor lead from the controller. Connect
an ohmmeter lead to the ice thickness sensor lead,
touch the other ohmmeter lead to the ice machine
chassis. There must be an open circuit. If there is
continuity, the sensor must be replaced. If there is
no continuity, touch the ohmmeter lead to the metal
part of the ice thickness sensor. There should be
continuity. If open, check the ice thickness sensor
for scale build up. Clean and recheck. If still open,
replace the ice thickness sensor.
3. Test the controller’s ice thickness sensor circuit
by connecting a wire from J10 to ground.
Reconnect electrical power. The Ready for Harvest
light should go ON.
May 2008
Page 34
CU1526, CU2026, CU3030
Service Manual
Curtain Switch
Ice Thickness Sensor