Service Diagnosis - Scotsman CME506R Product Manual

CME506R, 656R, 806R: AutoIQ Cubers

Service Diagnosis

Problem or Symptom
Poor harvest
Low capacity
Compressor cycles on and off
Possible Cause
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
Low pressure (pump down)
control opening and closing
Compressor overheats
January 2000
Page 30
Probable Correction
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 frost on the
evaporator end of the hot gas
inlet tube. If not, replace the hot
gas valve
Separate and insulate them
Check the low side pressure,
the liquid line valve must open
and the low side pressure must
rise over 35 PSIG before the
pump down control will close to
run the compressor.
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