Hoshizaki KM-230BAJ Service Manual page 18

4) Initial Harvest Cycle – The 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 – The compressor remains energized, pump motor, (line valve if
applicable), 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 which
starts after the thermistor temperature reaches 36°F (2°C). After this period, the
freeze cycle operation is transferred to the float switch for freeze termination. During
the first 5 minutes of freeze, confirm that the evaporator temperature drops. After the
minimum freeze period, disconnect the float switch at the 2-pin connector attached to
the red wires. 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 fill the
reservoir, if there are improper unit pressures or an inoperative compressor. If the
unit remains in freeze with the float switch removed, replace the 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 – The compressor remains energized, the hot gas valve energizes,
the fan motor de-energizes. The drain valve and pump motor energize, allowing
water to drain from the tank for 10 seconds. This removes contaminants from the
water tank. Diagnosis: If the drain valve does not open, check the circuit. Check for
proper voltage. If water does not drain out, check and clean the tubing at the drain
valve and then check and clean the valve assembly.
7) Normal Harvest Cycle – same as the initial harvest cycle – Return to step 4.
8) Shutdown – See "II. D. 1 Bin Control Check". Note that after a bin-control initiated
shutdown, there is a 90 second minimum off time.
Note: Unit continues to cycle until bin control is satisfied or power is turned 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
fill cycle.
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