Service Manual

Section 4 Ice Machine Sequence of Operation
Part No. 80-1100-3 4-3
Remote
Q450/Q600/Q800/Q1000/Q1300/Q1600/Q1800
INITIAL START-UP OR START-UP AFTER
AUTOMATIC SHUT-OFF
1. Water Purge
Before the compressor 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.
The harvest valve and harvest pressure regulating
(HPR) solenoid valves also energize during water purge,
although they stay on for an additional 5 seconds (50
seconds total on time) during the initial refrigeration
system start-up.
2. Refrigeration System Start-Up
The compressor and liquid line solenoid valve energize
after the 45 second water purge and remain on
throughout the entire Freeze and Harvest Sequences.
The water fill valve is energized at the same time as the
compressor. It remains on until the water level sensor
closes for 3 continuous seconds, or until a six-minute
time period has expired. (See “Water Inlet Valve Safety
Shutoff,” Page 6-50.). The harvest valve and HPR
solenoid valves remain on for 5 seconds during initial
compressor start-up and then shut off.
The remote condenser fan motor starts at the same time
the compressor starts and remains on throughout the
entire Freeze and Harvest Sequences. (The compressor
and condenser fan motor are wired through the
contactor, therefore, anytime the contactor coil is
energized, the compressor and fan motor are on.)
FREEZE SEQUENCE
3. Prechill
The compressor is on for 30 seconds prior to water flow,
to prechill the evaporator.
4. 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. The water fill valve
will cycle on and then off one more time to refill the water
trough. (See Page 4-1.)
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.
Figure 4-4. Freeze Sequence (Typical Q450 Shown)
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