Water Level Control Circuitry; Water Level Probe Light; Water Inlet Valve Safety Shut-Off; Freeze Cycle Circuitry - Manitowoc QR0320A Service Manual

Electrical System

Water Level Control Circuitry

WATER LEVEL PROBE LIGHT

The water level probe circuit can be monitored by
watching the water level light. The water level light is on
when water contacts the probe, and off when no water is
in contact with the probe. The water level light functions
any time power is applied to the ice machine, regardless
of toggle switch position.
Figure 6-25. Freeze Cycle Water Level Setting
During the freeze cycle, the water level probe is set to
maintain the proper water level above the water pump
housing. The water level is not adjustable. If the water
level is incorrect, check the water level probe for
damage (probe bent, etc.). Repair or replace the probe
as necessary.

WATER INLET VALVE SAFETY SHUT-OFF

In the event of a water level probe failure, this feature
limits the water inlet valve to a six-minute on time.
Regardless of the water level probe input, the control
board automatically shuts off the water inlet valve if it
remains on for 6 continuous minutes. This is important to
remember when performing diagnostic procedures on
the water level control circuitry.
6-50

FREEZE CYCLE CIRCUITRY

Manitowoc's electronic sensing circuit does not rely on
float switches or timers to maintain consistent water
level control. During the freeze cycle, the water inlet
valve energizes (turns on) and de-energizes (turns off) in
conjunction with the water level probe located in the
water trough.
During the first 45 seconds of the Freeze Cycle:
• The water inlet valve is on when there is no water in
contact with the water level probe.
• The water inlet valve turns off after water contacts
the water level probe for 3 continuous seconds.
• The water inlet valve will cycle on and off as many
times as needed to fill the water trough.
After 45 seconds into the Freeze Cycle:
The water inlet valve will cycle on, and then off one more
time to refill the water trough. The water inlet valve is
now off for the duration of the freeze sequence.

HARVEST CYCLE CIRCUITRY

The water level probe does not control the water inlet
valve during the harvest cycle. During the harvest cycle
water purge, the water inlet valve energizes (turns on)
and de-energizes (turns off) strictly by time. The harvest
water purge adjustment dial may be set at 15, 30 or 45
seconds.
CONTROL BOARD
SV1616
NOTE: The water purge must be at the factory setting
of 45 seconds for the water inlet valve to energize during
the last 15 seconds of the Water Purge. If set at 15 or 30
seconds the water inlet valve will not energize during the
harvest water purge.
HARVEST
30
WATER PURGE
ADJUSTMENT
15
Section 6
45
SV1617
Part No. 80-1100-3