Service diagnosis – Scotsman NME454 User Manual
Page 22
NME454, 654 & FME504, 804
January 2007
Page 22
SERVICE DIAGNOSIS
Symptom
Possible Cause
Probable Correction
No ice is made, nothing operates
Unit off due to no power
Restore Power
Unit off due to master switch in OFF
position.
Switch master switch to ON.
Unit off due to low water level.
Check water supply, filter, strainer,
float valve. Correct water supply.
Unit off due to ice level sensors
(photo-electric eyes) blocked.
Check/clean ice level sensors.
Unit off due to scale on water level
sensor.
Clean water level sensor.
Unit off due to high pressure control
open.
Check for water interruption (water
cooled) or fan motor failure (air cool).
Auger motor hums but does not turn.
Auger can’t turn. Circuit board has not
yet shut unit down.
Unit is shut down
Circuit board has shut ice machine
down due to high auger motor amp
draw. Check for cause of high amp
draw, including bearings, gearmotor
condition and scale on auger and in
evaporator.
Low pressure control open
Auger not turning due to: motor
failure; auger relay failure on circuit
board; or gears stripped. Check drive
train.
TXV restricted or not metering. Check
bulb temperature.
Lack of refrigerant. Check for leak.
Check for a restricted system
No power to circuit board.
Check harness
Hi or low pressure cut outs open
Circuit Board gear motor relay will not
close
Check, replace board
Water level or ice level sensor failed.
Check, replace sensor
No ice, auger motor is turning
Compressor contactor coil is open
Check/replace contactor
Compressor will not start
Check start capacitor.
Check start relay
Check compressor windings
Circuit board compressor relay will
not close.
Check, replace board
Unit makes ice, but very slowly.
High discharge pressure because of a
dirty condenser
Clean the air filter and condenser.
Low capacity because the auger and
evaporator are coated with mineral
scale
Clean the water system
Low suction pressure due to low
refrigerant charge
Locate leak. Recover refrigerant,
repair leak, replace dryer, evacuate
and weigh in the nameplate charge