Sequence Of Operation - Scotsman Prodigy Plus A Series Service Manual

NH0422, NS0422, FS0522, NH0622, NS0622, FS0822, NH0922, NS0922, FS1222, NH1322, NS1322, FS1522
Air, Water or Remote Service Manual

Sequence of Operation

The ice machine's function is to continuously produce
ice until the ice level control senses that there is
enough ice in the bin or dispenser. There are three
systems that operate in close coordination to make
ice. They are the electrical system, the water system
and the refrigeration system.
The electrical system includes the compressor, auger
drive assembly, fan motor and control system (the
auger drive assembly includes the gear reducer,
auger and top bearing).
The water system includes the float valve, reservoir,
inside of the evaporator and the drain tubing.
The refrigeration system includes the compressor,
condenser, expansion valve and outside of the
evaporator.
Control System
As noted, the electrical system includes a control
system. The control system consists of a controller
and sensors. It automatically operates the machine
to make ice only when needed. It also monitors the
refrigeration system, water system and auger drive
assembly for proper function.
Sensors are used to monitor the machine. A continuity
probe water sensor is located near the float reservoir.
A tube from the float tank allows water to touch
the sensor's two stainless steel probes, making
a connection between them. That signals to the
controller the presence of water. The controller will not
allow the machine to make ice unless this sensor's
probes have continuity.
A set of photo-electric eyes (infrared emitter and
receiver) is located at the base of the ice discharge
chute. They are used to sense ice. As ice is made,
it falls through the infrared beam from the emitter,
causing the receiver to detect it. When ice has filled
the bin, the top of the ice pile will continuously stop
the beam, breaking the light to the receiver, and that
signals to the controller that the bin is full
Additionally, the control system uses the photo-eyes
to confirm ice making. As the machine makes ice,
the falling ice causes breaks in the infrared beam.
In operation, the first 6 minutes of ice making are
ignored to give the machine time to start producing
ice. After that, the controller will look for a minimum of
one beam-break in 10 minutes. If this is not achieved,
the control will shut the machine down for 10 minutes
and add the incident to a strike counter. During the
wait period, a 1 will be flashing in the code display.
After the 10 minute wait, the machine will restart. If no
ice is sensed three times in a row, the machine will
shut down on a no ice error and must be manually
reset. The 1 in the code display will change from
flashing to continuous.
If ice is detected within 10 minutes after any restart,
the strike counter will be reset to zero, and the code
display will show F, for freeze mode.
The auger drive motor amperage is monitored by
the controller. If the auger motor is overloaded
and is drawing too many amps, the controller will
shut the machine off, and a 2 will be flashing in the
code display. The controller will attempt a restart of
the auger motor in 4 minutes. If during the first 60
seconds after restart the auger motor current stays
within limits, the compressor is restarted and the
machine returns to normal operation. If the auger
motor's current is excessive within 60 seconds after
the restart, the process will be repeated once more.
If during that try the current is still excessive the
machine shuts down and must be manually reset.
The 2 in the code display will change from flashing to
continuous.
Water System
The water level in the evaporator is maintained by a
float valve in a separate reservoir. As ice is made, and
water is used, the water level in the reservoir drops,
opening the float valve. The open valve adds water to
the reservoir to resupply it.
July 2020
Page 24