Manitowoc I0320A, Technician'S Handbook

Page: 82 / 182

80 Part Number STH038 5/12
Freeze Sequence
3. Prechill
The compressor lowers the temperature of the
evaporator(s) before the water pump is energized. The
water fill valve will energize and remain on until water
completes the water level probe circuit.
4. Freeze
The water pump(s) energizes and water flows over the
evaporator. After water contacts the water level probe
the water fill valve de-energizes. The control board will
automatically cycle the water fill valve within the 6
minute water fill time limit. The valve energizes once in
the pre-chill and up to twice in the freeze cycle.
The freeze cycle continues until the six minute freeze
lock expires and enough ice has formed to send a
signal from the ice thickness probe to the control
board.
Harvest Sequence
5. Water Purge
The air pump(s) (when used) and the harvest valve(s)
open at the beginning of the water purge to divert hot
refrigerant gas into the evaporator.
The water pump(s) continues to run, and the water
dump valve energizes to purge the water in the water
trough.
6. Harvest
The air pump (when used) remains energized and the
harvest valve(s) remains open. 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 opens the water curtain/ice
damper and 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.)