Scotsman CME650R - Manual (Page 25)

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 thermostat adjusted to open
too soon. Rotate knob on the thermostat
clockwise to a colder setting.
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
CME650R
October 1994
Page 25