Manitowoc Indigo ID0302A, Technician'S Handbook

Page: 102 / 296

102 Part Number STH025 11/16
Freeze Sequence
3. Prechill
The compressor is on for 30 seconds (120 seconds initial
cycle) to lower the temperature of the evaporator(s)
before the water pump is energized. The water fill valve
will energize and remain on until water touches the low
and high, water level probes.
4. Freeze
Water Pump
The water pump(s) energizes and water flows over the
evaporator. The water pump is energized throughout the
freeze cycle.
Water Inlet Valve
The water inlet valve energized in prechill (30 seconds)
and can energize up to two times in the freeze cycle.
The control board will prevent the water fill valve from
energizing after two 6 minute water fill time limits.
After water contacts the low and high water probes the
water fill valve de-energizes. Ice builds on the evaporator
and the water level drops. When water loses contact with
the high water probe, the water fill valve energizes until
water contacts the high water probe again.
Ice Thickness Probe
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.
During the first 6 minutes of the freeze cycle the ice
thickness probe microphone samples ambient noise.
6 minutes into the freeze cycle 4 baseline readings are
recorded. Ice formation on the evaporator will change
the readings; when two of the four baseline readings are
exceeded a harvest cycle starts.