Scotsman MDT6N90 - Manual (Page 11)

ELECTRICAL SEQUENCE
Refer the wiring diagram as needed.
The “Power” light on the board glows whenever
there is power to the machine (and the master
switch is ON).
If the machine is switched off at the master switch,
but is otherwise ready to go, switching the master
switch to ON does the following:
· The bin empty and power lights on the circuit
board glow.
· There is a 15 second delay
· If there is enough water in the reservoir, the
circuit board will allow the machine to start up.
Start up consists of:
· The compressor contactor coil receives power
from the circuit board.
· The contactor is energized, connecting power to
the compressor, and the compressor starts.
· The auger motor receives power from the circuit
board and starts.
· As ice goes past the ice level sensors, the bin
empty light will stay on and the machine will
continue to run, unless the ice stays between
the sensors for more than 15 seconds (bin full).
At that point, the bin empty light goes out, and
the machine shuts down.
Other reasons for shut down:
· Low water level (as sensed by the thermistor in
the reservoir).
Shut Down consists of:
· The compressor contactor opens
· The compressor stops
· The auger motor is run by the circuit board for 2
more minutes, clearing out ice in the evaporator,
and then
· The auger motor no longer receives power from
the circuit board, and the auger motor stops.
After a 6 minute delay, If the ice level sensor is
clear (bin empty) for more than 15 seconds, the
machine will start up again.
Another purpose of the circuit board is to turn the
machine off if there is not enough water in the
machine.
· When the water level in the reservoir falls
below the tip of the water level sensor, the
machine will “shut down”
· After a 6 minute delay, if the water refills the
reservoir, the machine will start up again.
Separate from the circuit board:
· If the high pressure control (cut out switch)
opens, the compressor will stop immediately
(through the contactor). It will automatically
reset when the discharge pressure drops below
350 PSIG.
· The master switch is the manual control for the
complete machine, but it is not a service
disconnect.
Ice Vending
· When a user places a container in front of the
Touch Free ice sensor and below the ice
delivery chute, the circuit board connects power
to the bin drive motor and ice is dispensed for
as long as the container is present. If the user
does not remove the container, ice will be
dispensed for 60 seconds and then stop.
MDT6N90
May 2001
Page 11