Refrigeration Components; Head Pressure Control Valve - Koolaire KDT0300A Technician's Handbook

Refrigeration Components

HEAD PRESSURE CONTROL VALVE

Manitowoc remote systems require head pressure control
valves with special settings. Replace defective head
pressure control valves only with "original" Manitowoc
replacement parts.
Refrigerant Charge Verification
The correct amount of refrigerant (name plate charge) is
required to operate correctly at all ambient conditions.
An ice machine with an overcharge or undercharge of
refrigerant may function properly at higher ambient
temperatures and fails at lower ambient temperatures.
Symptoms of incorrect refrigerant amount are:
•Works during the day and malfunctions at night, and/or
fails whenever the outdoor temperature drops.
•A Safety limit is stored in control board memory.
Refrigerant loss and ambient temperature are directly
related to each other. As the ambient temperature drops,
more refrigerant is stored in the condenser.
When the refrigerant charge and ambient temperature
create an undercharge of refrigerant in the freeze cycle,
the receiver dip tube will lose it's liquid seal. Without liquid
refrigerant to the TXV, the ice machine fails to make a full
sheet of ice in 60 minutes and a safety limit #1 results.
NOTE: When a head pressure control valve is being
replaced or refrigerant charge is suspected, verify the
refrigerant charge is correct by recovering the refrigerant,
weighing and comparing to the nameplate amount.
Refer to Refrigerant Recovery/Evacuation for recovery
procedures.
94 Part Number STH063 9/17