Manitowoc Q130 series, Technician'S Handbook

Page: 154 / 236

154 Part Number 8001119 10/19
Other
• Non-Manitowoc components in system
• Improper water supply over evaporator refer to
“Water System Checklist” on page 105.
• Loss of heat transfer from tubing on back side of
evaporator
• Restricted/plugged liquid line drier
• Restricted/plugged tubing in suction side of
refrigeration system
NOTE: Do not limit your diagnosis to only the items
listed in the checklists.
HOT GAS VALVE
General
The hot gas 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 receiver and the
evaporator and performs two functions:
1. Prevents refrigerant from entering the evaporator
during the freeze cycle.
The hot gas valve is not used during the freeze
cycle. The hot gas 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 hot gas 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. Harvest pressures can be found in the
“Cycle Time/24 Hour Ice Production/Refrigerant
Pressure Charts” in this book.