SERVICE DIAGNOSIS: Refrigeration and/or Mechanical
SYMPTOM
POSSIBLE CAUSE
PROBABLE FIX
Poor harvest
Hot gas valve does not open
Check for power to the coil, check for
not opening, replace
Head pressure control valve does not
maintain enough head pressure.
Replace head pressure control valve.
Unit cycles off during freeze or
harvest
Hi temperature switch opens and
closes
Hot gas valve leaks thru, replace it
Low capacity
High head pressure, from dirty
condenser, faulty fan motor
Clean condenser, repair fan motor
Non condensable gas in the system
Purge system, evacuate and weigh in
nameplate charge
Extreme hot location
Relocate the cabinet
Overcharge of refrigerant
Evacuate and weigh in nameplate
charge
Hot gas valve leaks thru
At the end of the freeze cycle there
should be frost on the evaporator end
of the hot gas tubes, if not replace the
hot gas valve
Liquid and discharge lines are in
contact with each other
Separate and insulate them
Unit shuts off before bin is full
Bin Ice level control is set to “Partial”
Move bin Ice level rocker switch to
“Full”.
Compressor cycles on and off
Low pressure control opening and
closing
Check low side pressure, liquid line
valve must open and low side
pressure raise over 35 PSIG before
pump down control will close to run
compressor
Compressor overheats
TXV not letting enough refrigerant
into evaporators, adjust or replace
TXV
Mechanical fault with compressor,
replace compressor
Frost on compressor
Some frost will not hurt
Do nothing
TXV meters too much refrigerant
Adjust or replace TXV
CMS1402R
September 1993
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