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Section 3 Ice Machine Operation
Part Number 000001528 3-3
Ice Making Sequence of Operation
INITIAL START-UP OR START-UP AFTER
AUTOMATIC SHUT-OFF
1. Water Purge
Before the refrigeration system starts, the water pump
and water dump solenoid are energized for 45 seconds,
to completely purge the ice machine of old water. This
feature ensures that the ice making cycle starts with
fresh water.
FREEZE SEQUENCE
2. Prechill
Ice Machine Head Section: The liquid line solenoid
valve energize after the 45 second water purge and
remains on throughout the entire ice making Freeze and
Harvest Sequences. The liquid line solenoid is
energized for 30 seconds prior to water flow. This allows
the refrigeration system to start-up and prechills the
evaporator.
CVD Condensing Unit: When the refrigerant pressure
is high enough to close the low pressure switch, the
contactor coil is energized and the compressor and
condenser fan motor (CVD1475 only) start. They are
supplied with power throughout the entire Freeze and
Harvest Sequences. The fan motor (CVD1475 only) is
wired through a fan cycle pressure control, therefore it
may cycle on and off.
3. Freeze
The water pump restarts after the 30 second Prechill. An
even flow of water is directed across the evaporator and
into each cube cell, where it freezes.
When sufficient ice has formed, the water flow (not the
ice) contacts the ice thickness probe. After
approximately 7 seconds of continual water contact, the
Harvest Sequence is initiated. The ice machine cannot
initiate a Harvest Sequence until a 6-minute freeze lock
has been surpassed.
HARVEST SEQUENCE
4. Water Purge
The water pump continues to run, and the water dump
valve energizes for 45 seconds to purge the water in the
sump trough. After the 45 second water purge, the water
pump and dump valve de-energizes.
Both harvest solenoid valves also open at the beginning
of the water purge to divert refrigerant gas into the
evaporator.
5. Harvest
The harvest solenoid valves remain open and the
refrigerant gas warms each evaporator causing the
cubes to slide as a sheet, off the evaporator and into the
storage bin. The ice may fall first from either the right or
the left evaporator, or both at the same time. The sliding
sheet of cubes swings the water curtain out, opening the
corresponding bin switch.
The momentary opening and closing of the bin switch
de-energizes relay#2 (right) or #3 (left). Opening relay
#2 or #3 de-energizes the corresponding harvest
solenoid valve for the remainder of the Harvest
Sequence. The momentary opening and closing of both
bin switches terminates the Harvest Sequence and
returns the ice machine to the Freeze Sequence (steps
2-3).
AUTOMATIC SHUT-OFF
6. Automatic Shut-Off
Ice Machine Head Section: When the storage bin is full
at the end of a harvest sequence, the sheet of cubes
fails to clear either one or both water curtains. After one
or both water curtains are held open for 7 seconds, all
five relays are held open the ice machine shuts off.
CVD Condensing Unit: When the refrigerant pressure
is low enough to open the low-pressure switch, the
contactor coil is de-energized and the compressor and
condenser fan motor (CVD1475 Only) stop.
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(s). As the water curtain(s) swing
back to the operating position, the bin switch re-closes
and the ice machine restarts (steps 1 - 2).Both curtains
must be closed to start an ice making sequence.