Manitowoc Q450 Service Technician's Handbook page 123

4. Using the information gathered, refer to the chart
below.
NOTE: A headmaster that will not bypass, will function
properly with condenser air temperatures of
approximately 70°F (21.1°C) or above. When the
temperature drops below 70°F (21.1°C), the
headmaster fails to bypass and the ice machine
malfunctions. Lower ambient conditions can be
simulated by rinsing the condenser with cool water
during the freeze cycle.
Symptom
Valve not
maintaining
pressures
Discharge pressure
low; Liquid line
entering receiver
feels warm to hot
Discharge pressure
extremely high;
Liquid line entering
receiver feels hot
Discharge pressure
low; Liquid line
entering receiver
feels extremely cold
Probable
Cause
Non-
approved
valve
Ice machine
low on
charge
Valve stuck in
bypass
Valve not
bypassing
–113–
Corrective
Measure
Install a Manitowoc
Headmaster control
valve with proper
setting
See "Low on
Charge Verification"
Replace valve
Replace valve