Harvest Sequence; Automatic Shut-Off; Safety Timers; Warm Water Rinse Cycle - Manitowoc S Service Manual

Section 3

HARVEST SEQUENCE

5. Water Purge
The harvest valve(s) opens at the beginning of the water
purge to divert hot refrigerant gas into the evaporator.
The water pump continues to run, and the water dump
valve energizes for 45 seconds to purge the water in the
sump trough. The water fill valve energizes (turns on)
and de-energizes (turns off) strictly by time. The water fill
valve energizes for the last 15 seconds of the 45-second
water purge.
After the 45 second water purge, the water fill valve,
water pump and dump valve de-energize. (Refer to
"Water Purge Adjustment" for details.)
6. Harvest
The harvest valve(s) remains open and the refrigerant
gas warms the evaporator causing the cubes to slide, as
a sheet, off the evaporator and into the storage bin. The
sliding sheet of cubes swings the water curtain out,
opening the bin switch.
The momentary opening and re-closing of the bin switch
terminates the harvest sequence and returns the ice
machine to the freeze sequence (Step 3 - 4.)
When Used - The air compressor energizes after 35
seconds and remains energized throughout the entire
harvest cycle. The air compressor will automatically
energize for 60 seconds when the harvest cycle time
exceeded 75 seconds in the previous cycle.

AUTOMATIC SHUT-OFF

7. Automatic Shut-Off
When the storage bin is full at the end of a harvest
sequence, the sheet of cubes fails to clear the water
curtain and will hold it open. After the water curtain is
held open for 30 seconds, the ice machine shuts off. The
ice machine remains off for 3 minutes before it can
automatically restart.
The ice machine remains off until enough ice has been
removed from the storage bin to allow the ice to fall clear
of the water curtain. As the water curtain swings back to
the operating position, the bin switch re-closes and the
ice machine restarts (steps 1 - 2), provided the 3 minute
delay period is complete.
Part Number 80-1480-3

SAFETY TIMERS

The control board has the following non-adjustable
safety timers:
• The ice machine is locked into the freeze cycle for 6
minutes before a harvest cycle can be initiated.
Freeze lock is bypassed after moving the toggle
switch from OFF to ICE position for the first cycle
only.
• The maximum freeze time is 60 minutes at which
time the control board automatically initiates a
harvest sequence (steps 5 & 6).
• The maximum harvest time is 3.5 minutes at which
time the control board automatically initiates a freeze
sequence (steps 3 & 4).

WARM WATER RINSE CYCLE

Closing the back of the evaporator allows ice to build up
on the rear of the evaporator and the plastic evaporator
frame parts. After 200 freeze/harvest cycles have been
complete the control board will initiate a warm water
rinse.
After the 200th harvest cycle ends:
• The Clean and Harvest LED's energize to indicate
the ice machine is in a warm water rinse.
• The compressor and harvest valve remain
energized.
• The water pump energizes.
• The water inlet valve energizes until water contacts
the water level probe.
• The compressor and harvest valve warm the water
for 5 minutes, then de-energize.
• The water pump remains energized for an additional
5 minutes (10 minute total on time) then de-
energizes.
NOTE:
The warm water rinse cycle can be terminated by
moving the toggle switch to the OFF position, then back to ICE.
Ice Machine Operation
3-3