Hoshizaki MODULAR CRESCENT CUBER KM-650MWH - Manual (Page 13)

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B. Sequence of Operation
The steps in the sequence are as outlined below. When power is supplied, a 5 second
delay occurs at startup. Note that the order of the LEDs from the outer edge of the board is
1, 4, 3, 2.
1. One Minute Fill Cycle
LED 4 is on. WV opens and the fill period begins. After 1 minute, the board checks for
a closed F/S. If F/S is closed, the harvest cycle begins. If not, WV will remain energized
through additional 1 minute cycles until water enters the sump and F/S closes. This serves
as a low water safety to protect the water pump.
2. Initial Harvest Cycle
LEDs 1, 4, and 2 are on. WV remains open, Comp and FMR energize, HGV opens,
and harvest begins. As the evaporator warms, the thermistor located on the suction line
checks for a 48°F (9°C) temperature. When 48°F (9°C) is reached, a 3.9 kΩ signal turns
the harvest over to the adjustable harvest timer which is factory set for normal conditions.
The timer has settings of 60, 90, 120, and 180 seconds (dip switch 1 & 2). The water valve
is open during harvest for a maximum of 6 minutes or the length of harvest, whichever is
shorter. When the harvest timer completes its count down, the harvest cycle is complete
and the freeze cycle starts. The minimum total time allowed by the board for a complete
harvest cycle is 2 minutes.
3. Freeze Cycle
LED 1 is on. Comp and FMR continue to run, PM and FMS energize, LLV opens, HGV
and WV close and the freeze cycle starts. For the first 5 minutes the control board will not
accept a signal from F/S. This 5 minute minimum freeze acts as a short cycle protection. At
the end of 5 minutes, F/S assumes control. As ice builds on the evaporator the water level
in the sump lowers. The freeze continues until F/S opens and terminates ice production.
4. Pump-Out Cycle
LEDs 1, 3, and 2 are on. Comp and FMR continue to run, HGV opens, LLV closes, and
FMS deenergizes. PM stops for 2 seconds and reverses, taking water from the bottom of
the sump and forcing pressure against the check valve seat allowing water to go through
the check valve and down the drain. At the same time water flows through the small tube
to power flush the F/S. When the pump-out timer stops counting, the pump out is complete.
Pump out always occurs on the 2nd harvest after startup. Then, depending on the control
board setting, pump out occurs every cycle, or every 2nd, 5th or 10th cycle (dip switch 5 &
6).
5. Normal Harvest Cycle
LEDs 1, 4, and 2 are on. Comp and FMR continue to run, HGV remains open and WV
opens. As the evaporator warms, the thermistor reaches 48°F (9°C). The control board
then receives the thermistor's 3.9 kΩ signal and starts the harvest timer. The water valve
is open during harvest for a maximum of 6 minutes or the length of harvest, whichever is
shorter. When the harvest timer completes its count down, the harvest cycle is complete
and the next freeze cycle starts. The unit continues to cycle through 3, 4 and 5 sequence
until the bin control senses ice and shuts the unit down.
Legend: Comp–compressor; FMR–remote fan motor; FMS–self-contained fan motor;
F/S–float switch; HGV–hot gas valve; LLV–Liquid Line Valve; PM–pump motor;
WV–inlet water valve