Initial Start-up. Manitowoc Ice Sotto - UG Series Technician's Handbook

Ice Making Sequence of Operation

INITIAL START-UP

1.

Water Inlet and Pressure Equalization

Turn the toggle switch to the “ON” position, the water fill valve and harvest valve are energized, and 300 seconds later, the water fill valve is de-energized. 20 seconds after the harvest valve solenoid is energized, the compressor is energized. 300 seconds after the compressor is energized, the harvest valve solenoid is de-energized, the water pump and the fan motor are energized, and the machine goes into freeze cycle.

2.

Freeze Cycle

As the ice making process begins, the pump sprays water into the inverted cups. The water freezes layer by layer, until an ice cube forms in each cup.

When the water temperature in the sump is equal to or less than 2 °C for more than 5 seconds, the control board will read the settings of “liquid line temperature” and dip switch and obtain the “freeze postpone time” and “fan shut off time”. Before the end of the freeze cycle, the control board may shut off the fan motor to assist harvest.

When the “freeze postpone time” has elapsed, the harvest cycle is initiated.

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3.

Harvest Cycle

The compressor continues to operate and the water pump is de-energized. The hot gas valve energizes, allowing hot refrigerant vapor to enter and warm the evaporator. The water valve is also energized, aiding with harvest, as well as filling up the sump with fresh water for a new freeze cycle.

At the point of 2 minutes to freeze end, the board will read the “liquid line temperature” again and calculate the

“harvest time”.

The ice falls from the cups and is directed into the bin by the ice chute. The harvest cycle continues until the

“harvest time” has elapsed, and then the machine goes into a new freeze cycle.

4.

Automatic Shut-Off

When the storage bin is full, the ice will come in contact with the bin thermostat which is located inside the bin.

The machine will stop after approximately 45 seconds of continuous ice contact with the bin thermostat probe.

The ice machine remains off until a 3 minute delay has elapsed and enough ice has been removed from the storage bin to allow the ice to fall clear of the bin thermostat probe. As the ice clears the probe, the bin thermostat warms up to above the set value and the machine starts another freeze cycle.

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