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4) Initial Harvest Cycle – Inlet water valve remains energized, contactor coil energizes to
start the compressor (and fan motor on a remote condenser unit), and the hot gas valve
energizes. The evaporator warms and the thermistor senses 48°F (9°C). The control
board then receives the thermistor's 3.9 kΩ signal and turns operation of harvest over
to the harvest timer. The timer completes counting (1 to 3 minutes). The unit then cycles
to freeze. Diagnosis: Check if compressor is running, hot gas valve is open, water
valve still open. Average harvest cycle at factory setting is 2 to 3 minutes. How long
does initial harvest last? 1.5 minutes after initial harvest begins, touch the compressor
discharge line. Is it hot? If not check refrigerant pressures and compressor operation.
If it is hot, touch the inlet line to the evaporator. Is it hot? If it is hot and the freeze cycle
is not starting, check the harvest timer adjustment, the thermistor for open circuit, the
discharge line temperature, compressor efficiency, and if the hot gas valve is fully open.
5) Freeze Cycle – compressor remains energized, pump motor, (line valve on remote
condenser unit), and fan motor energize. The inlet water valve and hot gas valve
de-energize. The unit is held in freeze by a 5 minute short cycle protection timer.
After 5 minutes, the freeze cycle operation is transferred to the oat switch for freeze
termination. During the rst 5 minutes of freeze, conrm that the evaporator temperature
drops. After 7 minutes in freeze, remove the black oat switch lead from the K5
connector. The unit should immediately switch to the pump-out cycle. Diagnosis: If the
evaporator is not cold, check to see if the hot gas valve is still open or if the expansion
valve is not opening properly, if the water valve is continuing to ll the reservoir, if there
are improper unit pressures, an inoperative compressor, or an inoperative headmaster
(C.P.R.) (remote condenser unit only). If the unit remains in freeze with the oat switch
removed, replace the control board.
Note: Normal freeze cycle will last 20 to 40 minutes depending on model and
conditions. Cycle times and pressures should follow performance data provided in
this manual.
6) Pump-Out Cycle (10/20 second pump out) – the compressor remains energized,
the hot gas valve energizes, the fan motor de-energizes, the pump motor stops for
2 seconds and starts in reverse rotation for 10/20 seconds. (This removes contaminants
from the water reservoir through the check valve (drain valve) and down the drain and
allows for a power ush of the oat switch.) Check for clear tubing at the check valve
housing and check the unit drain for water ow. Diagnosis: If the pump motor does not
reverse, check the circuit and capacitor. If water does not pump out, remove the check
valve (drain valve) housing and check/clean the valve assembly.
7) Normal Harvest Cycle – same as the initial harvest cycle – Return to step 4.
Note: Unit continues to cycle until bin control is satised or power is switched OFF. (The
pump out cycle can be adjusted to occur every cycle, or every 2, 5, or 10 cycles.
The factory default is every 10 cycles.) The unit always restarts at the 1 minute ll
cycle.
8) Shutdown – When the unit is running hold ice in contact with the thermostatic bulb, the
thermostatic bin control switch opens within 10 seconds, shutting down the unit. The bin
control is factory set, and generally no adjustment is required. However, adjustment may
be needed in some conditions, particularly at higher altitude locations. Diagnosis:See
"IV.C.BinControlCheck."