Scotsman CME250 - Manual (Page 10)

COMPONENT DESCRIPTION: Control System
Cube Size Control
This reverse acting thermostat controls the length
of the freezing cycle. It is sensing the temperature
of the suction line. When the suction line gets cold
enough, the cube size control closes (on
temperature fall) and starts the timer. A change in
either ambient air or incoming water temperature
will affect the efficiency of the refrigeration system,
and this will vary the length of time it takes the
evaporator to reach the temperature at which the
cube size control is preset to close. See CUBE
SIZE ADJUSTMENT BEFORE attempting to adjust
the control.
Relay
The multi-function, three pole, double throw,
plug-in relay is installed directly into a receptacle
on the printed circuit board in the control box. The
relay functions in part to by-pass the bin
thermostat control to prevent the ice maker from
shutting OFF, when the bin thermostat opens
during the freezing cycle. The bypass action
serves to ensure full-sized ice cubes with each
harvest cycle.
Timer - Timer & Switch Assembly
The function of the timer begins when activated by
the cube size control. The outer surface, or large
diameter lobe of the timer cam, determines the
timer cycle for finish freezing of the ice cubes,
while the inner surface, or small diameter lobe,
determines the time cycle for the harvest cycle.
When the microswitch button is pushed in there is
power connected to the coil of the relay, and the
unit is in the freeze cycle. When the microswitch
button is released, the power to the relay is
stopped, and the unit goes into harvest. The
microswitch is actuated by a cam assembly
directly connected to the timer motor.
One complete rotation of the cam will take eight
minutes. Harvest is preset at two and a quarter
minutes, but is adjustable.
High Pressure Safety Cut Out Switch
This is a manual reset control that shuts down the
ice maker, should the discharge pressure ever
reach 450 PSIG (air cooled) or 400 PSIG (water
cooled). Located next to the control box.
Relay
Cube Size Control
Bin Thermostat
CONTROL BOX
Timer
High Pressure Cut
Out Switch
CME250
October 1994
Page 10