Scotsman CMS1202R Service Manual page 23

SERVICE DIAGNOSIS: Refrigeration and/or Mechanical
SYMPTOM
Poor harvest
Unit cycles off during freeze or
harvest
Low capacity
Unit shuts off before bin is full
Compressor cycles on and off
Frost on compressor
POSSIBLE CAUSE
Hot gas valve does not open
Head pressure control valve does not
maintain enough head pressure.
Hi temperature switch opens and
closes
High head pressure, from dirty
condenser, faulty fan motor
Non condensable gas in the system
Extreme hot location
Overcharge of refrigerant
Hot gas valve leaks thru
Liquid and discharge lines are in
contact with each other
Bin Ice level control is set to "Partial"
Low pressure control opening and
closing
Compressor overheats
Some frost will not hurt
TXV meters too much refrigerant
September 1993
Page 23
CMS1202R
PROBABLE FIX
Check for power to the coil, check for
not opening, replace
Replace head pressure control valve.
Hot gas valve leaks thru, replace it
Clean condenser, repair fan motor
Purge system, evacuate and weigh in
nameplate charge
Relocate the cabinet
Evacuate and weigh in nameplate
charge
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
Separate and insulate them
Move bin Ice level rocker switch to
"Full".
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
TXV not letting enough refrigerant
into evaporators, adjust or replace
TXV
Mechanical fault with compressor,
replace compressor
Do nothing
Adjust or replace TXV