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