Hoshizaki KM-515MAH Service Manual page 34

5) Freeze Cycle – LED 1 is on. Compressor (and fan motor on a remote air-cooled unit)
remains energized, pump motor, line valve (if applicable), and fan motor (self-contained
air-cooled unit) 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 the 5 minute
short cycle protection timer terminates, 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 5 minutes in freeze, remove the black
float switch lead from the K5 connector. The unit should switch out of the freeze 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, an inoperative compressor, or an
inoperative headmaster (C.P.R.) (remote air-cooled unit only). 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 (10/20 second pump out) – LEDs 1, 4, 3, 2 are on. The pump out
occurs after the 1st freeze cycle and every cycle thereafter. The pump-out frequency
control (S4 dip switch 5 & 6) should not be adjusted.
The compressor remains energized, the hot gas valve energizes, the fan motor
de-energizes (self-contained air-cooled unit only), the pump motor stops for 2 seconds
and starts in reverse rotation for 10/20 seconds. This removes contaminants from the
water reservoir. Diagnosis: If the pump motor does not reverse, check the circuit and
pump capacitor. If water does not pump out, check for clear tubing at the check valve
housing and check the unit drain for water flow. Remove the pump out check valve
housing and check/clean the valve assembly.
7) Normal Harvest Cycle – LEDs 1, 4, and 2 are on. The hot gas valve and compressor
remain energized and the inlet water valve energizes. The inlet water valve is open
during harvest for a maximum of six minutes or the length of harvest which ever is
shorter. 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
pump-out timer's harvest timer. When the pump-out timer's harvest timer is complete,
the freeze cycle starts. Diagnosis: Check if compressor is running, hot gas valve is
open, inlet 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 pump-out timer adjustment, the
thermistor for open circuit, the discharge line temperature, compressor efficiency, and if
the hot gas valve is fully open.
Note: Unit continues to cycle until bin control is satisfied or power is switched off. The
unit always restarts at the 1 minute fill cycle.
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