Manitowoc Ice QM30 manual Initial START-UP or START-UP After Automatic SHUT-OFF

Section 3

Operation

Sequence of Operation

		Control Board Relays
Ice Making Sequence	1	2	3	Length of
of Operation		Hot Gas Valve	Water Pump
	Compressor			“ON” Time
		Water Fill Valve	Fan Motor
Start-Up*	off	on	on	2.9 Minutes
1.Water Purge				(175 Seconds)
2.Refrigeration
	on	on	off	5 Seconds
System Start-Up
3.Freeze Cycle	on	off	on	Automatically deter-
				mined
4.Harvest Cycle	on	on	off	Automatically deter-
				mined
5.Auto Shut-Off	off	off	off	Until bin thermostat
				re-closes
*Initial Start-Up or Start-Up After Automatic Shut-Off
INITIAL START-UP OR START-UP AFTER AUTOMATIC SHUT-OFF
1. Water Purge		4. harvest cycle

The water fill valve and the hot gas valve are energized for 2.9 minutes (175 seconds). This ensures that the ice making cycle starts with fresh water, and that the refrigerant pressures are equalized prior to refrigeration system start-up.

2. Refrigeration System Start-Up

The compressor starts 2.9 minutes (175 seconds) after the water fill valve and hot gas valve are energized. (The water fill valve and hot gas valve remain energized for 5 seconds during compressor start-up, and then shut off.) The compressor remains on throughout the entire freeze and harvest cycles.

3. freeze cycle

The condenser fan motor and water pump are energized and remain on throughout the entire freeze cycle. An even flow of water is directed across the evaporator and into each cube cell, where it freezes.

The control system automatically determines the length of the freeze cycle by monitoring the temperature of the refrigeration system liquid line.

The condenser fan motor and water pump de-energize. The water fill valve energizes to purge the water in the water trough. The hot gas valve also energizes at the beginning of the harvest cycle to divert hot refrigerant gas into the evaporator. The hot refrigerant gas warms the evaporator, causing the cubes to slide, as a sheet, off the evaporator and into the ice storage bin.

The control system automatically determines the length of the harvest cycle, based on the temperature of the refrigeration system liquid line at the end of the freeze cycle. At the end of the harvest cycle, the ice machine returns to another freeze cycle.

5. automatic shut-off

The ice machine shut-off is controlled by the level of ice in the ice storage bin. When the bin is full, ice cubes contact the bin thermostat bulb holder, which cools down and opens to stop the ice machine. The ice machine remains off until enough ice has been removed from the bin. This causes the thermostat bulb holder to warm and close, restarting the ice machine. When the ice machine restarts, it returns to the start-up sequence.

Part Number 000001772 07/08 3-1