Manitowoc ICVD3095, Technician'S Handbook

Page: 265 / 350

Part Number Preliminary 6/11 265
Harvest Cycle Operation
QuietQube® Models
During the Harvest cycle, the harvest valve opens and
allows refrigerant from the top of the receiver tank to
enter the evaporator. The refrigerants change of state
(from vapor to liquid) releases the heat necessary for
the Harvest cycle.
Opening the harvest valve causes a drop in discharge
pressure.
The discharge pressure will drop below the condenser
fan cycling control setpoint and the condenser fan
motor cycles off (at ambient temperatures above
110°F (43°C) the condenser fan motor remains
energized).
The warm discharge gas adds heat to the receiver in
the harvest cycle. Without this additional heat the head
pressure would continue to drop as liquid refrigerant
boils off in the receiver.
Example: A service technician removes refrigerant
vapor from a cylinder by boiling off the liquid
refrigerant. A refrigeration effect is created as the
refrigerant changes state from a liquid to a vapor. The
cylinder cools and the refrigerant pressure drops. To
maximize flow and maintain pressure the technician
places the cylinder in warm water.