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

HARVEST SEQUENCE

5. Harvest
The water pump de-energizes stopping flow over the
evaporator. The rising level of water in the sump
trough diverts water out of the overflow tube, purging
excess minerals from the sump trough. The hot gas
valve also opens to divert hot refrigerant gas into the
evaporator.
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 contacts
the ice damper, 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 (steps 3 - 4).

AUTOMATIC SHUT-OFF

6. Automatic Shut-off
When the storage bin is full at the end of a harvest
sequence, the sheet of cubes fails to clear the ice
damper and will hold it down. After the ice damper is
held open for 7 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 damper. As the ice damper 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.
80 Part Number 80-01111-9 7/10