Technicians Only: Harvest Cycle Sequence of Operation
At the
beginning of harvest
, the controller:
·
Shuts off the Freeze light
·
Turns on the Harvest light
·
Opens the vapor inlet valve
·
Opens the condenser bypass valve
·
Closes the normally open liquid inlet valve
·
Shuts off the water pump
·
Opens the purge valve
·
Begins to time the harvest cycle
When the ice falls off the evaporators, it passes
through the two infrared light beams emitted by the
ice sensors in the ice chute. The falling ice breaks
the beams, signaling to the controller that ice is
being released.
During harvest
the controller:
·
Blinks the Bin Full light at every light beam
interruption to indicate that ice is being sensed
·
Changes the time measured from the beginning
of harvest to the time the last cube was sensed.
First Harvest Cycle
The first harvest cycle after a restart continues for
a default period of about 5 minutes. The next
cycle’s harvest time will be determined from the
actual time used to release ice in this cycle, and
will likely be much shorter.
Slow Ice Release
If ice releases slowly the controller will extend the
harvest cycle until it ice quits falling within the
normal harvest time or until it reaches the pre-set
maximum time. The controller will then return the
unit to the freeze cycle.
No Ice Released
If no ice is sensed harvest continues until it
reaches its pre-set maximum, when the controller
switches the unit back into freeze.
Shut Down - Maximum Harvest Time
If a maximum harvest time is reached again during
the next harvest cycle, the controller will shut the
system down and blink the refrigeration diagnostic
light. It will automatically attempt a restart in 50
minutes. If the maximum harvest time is reached
again in the next two consecutive cycles, the
controller will repeat the shut down and restart
process. If the system still requires a maximum
length harvest cycle the controller will shut the unit
down and must be manually reset.
Purge Valve
The purge valve is open for a fixed time period. At
the beginning of that time the pump is off, but after
the time determined by the Purge setting in the
controller, the pump starts and forces water out of
the reservoir. The pump stays on after the purge
valve closes. The inlet water valve opens for a few
seconds to add water (but not fill) the reservoir.
End of Cycle
At the end of the harvest cycle the controller
switches the Harvest light off and the Freeze light
on. If the ice sensors had been blocked
continuously for more than 5 seconds the controller
senses this as Bin Full and would then shut the
machine off and turn on the Bin Full light.
At the beginning of the Freeze cycle the inlet water
valve is turned on to fill the reservoir and the cycle
repeats.
Eclipse
ä
1300,1600
September 2003
Page 33
