Water Level Control Circuitry; Diagnosing Freeze Cycle Potable Water Level Control Circuitry - Manitowoc Marine Q 1800 Service Manual

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.
WATER LEVEL WATER
ABOVE HOUSING PUMP
WATER PUMP
IMPELLER HOUSING
110°
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.
WATER LEVEL
PROBE
PUMP
OUTLET
SV1616
Electrical System
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
HARVEST WATER PURGE
ADJUSTMENT
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.
45
30
15
SV1617
23