Test Procedures - Scotsman CU1526 Service Manual

CU1526, CU2026, CU3030
Service Manual

Test Procedures

Water Pump
1. Test using the controller's indicator lights. Check
the indicator light during the freeze cycle. The light
will be On for all but the 30 second anti-slush
period, so observe the light for one minute. When it
is On, check the water pump, it should be
operating. If not, check voltage to the pump. If low
check the voltage from the controller to ground.
The water pump pin is number 6. If there is voltage
at that pin to ground, but very low voltage at the
pump motor, there must be a broken wire in the
harness. If the voltage is low at pin 6, the controller
should be replaced.
2. Test using an ohmmeter.
Disconnect electrical power.
Electrical Shock
Hazard.
Disconnect electrical
power before
beginning diagnostic
procedure.
Unplug the water pump motor leads from the
harness. Measure the resistance of the motor
windings. If open, replace the pump. Measure
resistance to ground. If there is any, replace the
pump.
Purge valve
1. Test using the controller's indicator lights. Shut
unit off by holding the Off button for 3 seconds.
Wait four minutes. Push and release the On button,
observe the Purge Valve indicator light. As the unit
drains the reservoir, the purge valve will be
powered. When it gets power, the indicator light will
be ON. If the purge valve does not open to drain
the reservoir when its indicator light is on, do a
voltage check. Shut the unit down by holding the
Off button in for 3 seconds. Unplug the harness
connection from the purge valve. Wait four
minutes. Push and release the On button to restart
the machine. As the unit drains the reservoir, the
purge valve connection should receive full voltage.
If it does, the purge valve should be replaced. If
there is no voltage, check voltage from the
controller to ground. The purge valve pin is 3
(dump valve on wiring diagram). If there is voltage
from that pin to ground, but low voltage at the valve
harness connection, the harness has a broken wire
or poor connection and must be replaced. If the
voltage to ground is low, the controller should be
replaced.
Note: The coil of this valve is internally rectified,
and will normally show infinite resistance when
tested with an ohmmeter.
May 2008
Page 38