Scotsman FME2400R Service Manual page 25

SERVICE DIAGNOSIS: Condition - No Ice Being Produced
(Work on each system separately)
STATUS: GEAR MOTOR OPERATES, COMPRESSOR DOES NOT
A. Check the pump down control switch.
1. This pressure switch opens at 15 psig, and closes at 30 psig. If open check the low side pressure, if after
running the machine the switch opens at a pressure higher than 18 psig, replace the switch. If the liquid
line solenoid valve is open, the low side pressure should be above 30 psig, and the pump down (low
pressure) control should be closed. If the low side pressure is below 30 psig:
a. Check if the auger is turning, if it is not, remove the gearbox and:
Check for internal damage, repair and replace in the machine.
b. Check for low charge, add some refrigerant, if the unit begins to operate, (normal low
side pressure being about 32 psig) stop and look for a leak, recover, repair, replace the drier,
evacuate, and weigh in the nameplate charge. If, with added charge,
the unit does not operate:
Check for a restricted system, recover, replace the drier, evacuate, and weigh in a
nameplate charge.
Check for a Thermostatic Expansion Valve that does not open, if defective,
replace it. Recover, replace the drier, evacuate, and weigh in the nameplate charge.
c. Check the liquid line solenoid valve, it should have power to it, if not:
Check the connections on the circuit board. The liquid line (or compressor) relay
on the circuit board may have failed. If so, replace the circuit board.
If there is power to the valve, the coil may be open, or the valve jammed, replace
the valve
Note: Pump down control Cut In and Cut Out changed in May 1995. It was CI= 17, CO=2..
NME1850R & FME2400R
June 1995
Page 25