Ice Thickness Probe (Harvest Initiation) How The Probe Works; Harvest/Safety Limit Light; Freeze Time Lock-In Feature; Maximum Freeze Time - Manitowoc Marine Q 1800 Service Manual

Electrical System
Ice Thickness Probe (Harvest Initiation)
HOW THE PROBE WORKS
Manitowoc's electronic sensing circuit does not rely
on refrigerant pressure, evaporator temperature,
water levels or timers to produce consistent ice
formation.
As ice forms on the evaporator, water (not ice)
contacts the ice thickness probe. After the water
completes this circuit across the probe continuously
for 6-10 seconds, a harvest cycle is initiated.
Ice Thickness Probe

HARVEST/SAFETY LIMIT LIGHT

This light's primary function is to be on as water
contacts the ice thickness probe during the freeze
cycle, and remain on throughout the entire harvest
cycle. The light will flicker as water splashes on the
probes.
The light's secondary function is to continuously
flash when the ice machine is shut off on a safety
limit, and to indicate which safety limit shut off the
ice machine.

FREEZE TIME LOCK-IN FEATURE

The ice machine control system incorporates a
freeze time lock-in feature. This prevents the ice
machine from short cycling in and out of harvest.
The control board locks the ice machine in the
freeze cycle for six minutes. If water contacts the
ice thickness probe during these six minutes, the
harvest light will come on (to indicate that water is
in contact with the probe), but the ice machine will
stay in the freeze cycle. After the six minutes are
up, a harvest cycle is initiated. This is important to
remember when performing diagnostic procedures
on the ice thickness control circuitry.
20
To allow the service technician to initiate a harvest
cycle without delay, this feature is not used on the
first cycle after moving the toggle switch OFF and
back to ICE.

MAXIMUM FREEZE TIME

The control system includes a built-in safety which
will automatically cycle the ice machine into
harvest after 60 minutes in the freeze cycle.
ICE THICKNESS CHECK
The ice thickness probe is factory-set to maintain
the ice bridge thickness at 1/8" (3.2 mm).
NOTE: Make sure the water curtain is in place
when performing this check. It prevents water from
splashing out of the water trough.
1. Inspect the bridge connecting the cubes. It
2. If adjustment is necessary, turn the ice thickness
SV1729A
NOTE: Turning the adjustment 1/3 of a turn will
change the ice thickness about 1/16" (1.5 mm).
Make sure the ice thickness probe wire and the
bracket do not restrict movement of the probe.
should be about 1/8" (3.2 mm) thick.
probe adjustment screw clockwise to increase
bridge thickness, or counterclockwise to
decrease bridge thickness.
ADJUSTING
SCREW
1/8" (3.2MM)
ICE
THICKNESS
Ice Thickness Check
SV1208