Harvest Sequence; Automatic Shut-Off - Manitowoc QM20 Technician's Handbook

HARVEST SEQUENCE

4. Harvest Cycle
The condenser fan motor and water pump de-
energize. The water fill valve energizes to purge the
water in the water trough. The hot gas valve also
energizes at the beginning of the harvest cycle to
divert hot refrigerant gas into the evaporator. The hot
refrigerant gas warms the evaporator, causing the
cubes to slide, as a sheet, off the evaporator and into
the ice storage bin.
The control system automatically determines the
length of the harvest cycle, based on the temperature
of the refrigeration system liquid line at the end of the
freeze cycle. At the end of the harvest cycle, the ice
machine returns to another freeze cycle (step 3).

AUTOMATIC SHUT-OFF

5. Automatic Shut-off
The level of ice in the ice storage bin controls the ice
machine shut-off. When the bin is full, ice cubes
contact the bin thermostat bulb holder, which cools
down and opens to stop the ice machine. The ice
machine remains off until enough ice has been
removed from the bin. This causes the thermostat bulb
holder to warm and close, restarting the ice machine.
When the ice machine restarts, it returns to the start-
up sequence (steps 1 – 2).
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