CME456R
December 2000
Page 30
Service Diagnosis
Problem or Symptom
Possible Cause
Probable Correction
Poor Harvest
Scale in water system.
Clean water system.
Water or Air Temperatures too
cold
Check temps. Unit cannot
operate with water and air
temps below stated limits.
Low system charge
Recover and weigh charge.
Bypass solenoid does not open Check solenoid operation
Check valve leaks back
Replace check valve
Hot gas valve does not open
Check for power to the coil, if
there is power, replace the hot
gas valve
Head pressure control valve
does not maintain enough
pressure (in freeze)
Replace the head pressure
control valve
Low capacity
High discharge pressure, from a
dirty condenser or faulty fan
motor
Clean the condenser, repair the
fan motor
Extreme hot location
Relocate the cabinet
Extremely hot condenser
location
Move condenser or provide
shade
Overcharge of refrigerant
Recover, evacuate and weigh in
the nameplate charge
Hot gas valve leaks thru, unit off
on refrigeration error
At the end of the freeze cycle,
there should be a definite
difference in temperature
between the inlet and outlet of
the Hot Gas Valve. If not,
replace the hot gas valve
Liquid and discharge lines are
in contact with each other
Separate and insulate them
Compressor cycles on and off
Compressor overheats
Low on refrigerant, locate leak,
recover refrigerant, repair leak,
replace drier, evacuate and
weigh in the nameplate charge.
TXV superheat too high, check
charge, if charge is OK, replace
TXV
Mechanical fault with
compressor, replace
compressor
Internal relief valve opened,
check for cause of high
discharge pressure
