Manitowoc MD0420A, Technician'S Handbook

Page: 73 / 132

Part Number 040005626 5/17 73
Harvest Valve
General
The harvest valve is an electrically operated valve that
opens when energized, and closes when
de-energized.
Normal Operation
The valve is de-energized (closed) during the freeze
cycle and energized (open) during the harvest cycle.
The valve is positioned between the compressor
discharge line and the evaporator and performs two
functions:
1. Prevents refrigerant from entering the evaporator
during the freeze cycle.
The harvest valve is not used during the freeze
cycle. The harvest valve is de-energized (closed)
preventing refrigerant flow from the receiver into
the evaporator.
2. Allows refrigerant vapor to enter the evaporator in
the harvest cycle.
During the harvest cycle, the harvest valve is
energized (open) allowing refrigerant gas from the
discharge line of the compressor to flow into the
evaporator. The heat is absorbed by the
evaporator and allows release of the ice slab.
Exact pressures vary according to ambient
temperature and ice machine model. Harvest
pressures can be found in the Cycle Time/24 Hour Ice
Production/ Refrigerant Pressure Charts in this book.