Scotsman NM650 Service Manual page 21

SERVICE DIAGNOSIS: Condition - No Ice Being Produced
H. Check: The gear motor, the motor must turn at full speed or the compressor contactor will not
pull in. If the motor will not turn fast enough, check the auger and evaporator for scale build up.
If no power to the motor:
Check: The indicator lights on the circuit board, the bin empty light should be ON, the no water
light should be OFF .
1. If the bin empty and no water lights are off, check the transformer.
a. Transformer "load" side should have 12 to 15 volts. If not, check the "line" side. The line
side should have 115 volts. If the line side has the correct voltage and the
load side does not, replace the transformer.
2. If the transformer is good, and the bin empty light is OFF, check the ice level sensors.
a. Remove sensors by sliding them sideways out of the ice chute. Visually inspect them,
clean if needed.
b. Look through the ice chute "eye" hole for something blocking the ice chute.
c. If the unit still does not run, replace the ice level sensors.
d. If the bin empty light is still OFF, check the circuit board.
See the instructions at the end of the manual. If the machine operates with the
testor, and not by itself, the ice level sensors should be replaced.
3. If the transformer is fine, and the "no water" light is ON, check the water level sensor.
a. Check the water level in the reservoir, restore if low. If the water level is ok:
b. Remove the water level sensor from the reservoir and clean the tip if dirty.
CAUTION: THE TIP IS MADE OF GLASS
c. Replace the water level sensor. If the no water light is still on, check that the
"water sen" plug is firmly plugged into the circuit board.
d. If the no water light is still on, check the circuit board:
1. Unplug the "water sen" connector from the circuit board.
2. Plug "water sen" connector from the Scotsman Electronic Control tester into
the circuit board.
MORE INFORMATION ON THE TESTER CAN BE FOUND AT THE END OF THE MANUAL.
Check the gearmotor relay on the circuit board.
If the bin empty light is on, and the water level light is off, there should be power (after 15
seconds) at the com. terminal of the gearmotor relay, if not, replace the circuit board.
STATUS: NOTHING OPERATES
a. Move the water switch on the tester to "no water" and the no water light
on the circuit board should go on. If not, replace the board.
b. Move the water switch to the "water" position, the no water light should
go off and after 15 seconds, the machine should start, if not,
replace the circuit board.
If the machine works with the tester, and not by itself,
replace the water level sensor.
January, 1991
Page 21
NM650