How It Works - Air Cooled - Scotsman C0530SR-1 Technical Manual

How It Works - Air Cooled

Freeze Cycle. At start up the controller drains and refills the reservoir. The reservoir refills
when the mid length water level sensor probe is uncovered and continues to fill until the top
probe is in contact with water. When the reservoir has filled, the compressor and water pump
start. After the discharge pressure has increased past the cut in point of the fan pressure
control, the fan motor(s) will begin to operate and warm air will be discharged out the back of
the cabinet. The fan motor will switch on and off as the discharge pressure rises and falls.
Water flows over the evaporator as the refrigeration system begins to remove heat. When the
water temperature falls to a preset point, as measured by the water temperature sensor, the
controller shuts off the water pump for 30 seconds. The freeze cycle resumes when the pump
restarts and ice begins to form on the evaporator. As it forms, the water flowing over the ice
moves closer and closer to the metal tip of the ice thickness sensor. When it comes into
contact with the sensor for a few continuous seconds, that signals the controller that the freeze
cycle is complete.
The controller may shut the air cooled fan motor off for a variable period of time to build up
heat for harvest. This is dependant upon the temperature of the discharge line sensor.
Harvest Cycle. When the harvest cycle begins, the controller shuts off the fan motor, switches
on the hot gas valve, and through a parallel circuit, the harvest assist solenoid. After a few
seconds the purge valve opens and water is drained from the reservoir. Based on either the
automatic purge or manual purge setting, the pump and purge valve will be switched off at a
time determined to have drained enough water for that setting. The inlet water valve will open
to fill the reservoir anytime the mid length probe is uncovered, which occurs during the
reservoir drain cycle. Harvest continues as the hot discharge gas flows into the evaporator
serpentine, heating up the evaporator. At the same time the harvest assist solenoid is pushing
against the back of the ice slab. When the ice releases from the evaporator, it harvests as a
unit, and the harvest assist probe provides some additional force to push it off. When the ice
falls off it will force the curtain(s) open. An open curtain during the harvest cycle signals the
controller that the evaporator has released its ice. If this is a single evaporator machine the
controller will terminate harvest. If it is a two evaporator machine, the controller will continue
harvest until both curtains have opened. If one curtain remains open, the controller will shut the
machine down on bin full. Anytime harvest is complete the hot gas valve and harvest assist
solenoid are shut off. The harvest assist solenoid pin returns to its normal position by spring
pressure.
If the curtain(s) re-close after harvest, the freeze cycle will restart.
September 2006 Page 24