Scotsman CME306 - Manual (Page 24)

Technicians Only: Harvest Cycle Operational Sequence
Harvest
The (air cooled model) fan(s) is(are) off.
The purge valve opens, and will remain open for
40 seconds.
The water pump shuts off, it will restart in less than
40 seconds, depending upon the Purge Level set.
The water pump restarts and pumps out water thru
the open purge valve until the valve closes.
The inlet water valve then opens for about 22
seconds to add some water.
During the Harvest Cycle, ice will be falling from
the evaporators and between the ice sensor’s
electric eyes. The AutoIQ Controller monitors the
ice falling and stays in the Harvest Cycle until ice
quits going thru the electric eyes.
The maximum harvest time is 13 minutes. The first
Harvest after a restart will be a long one to
establish a base line, then the actual time it took to
release the ice is used to determine the length of
the next harvest cycle.
If no cubes fall (or are sensed) by the end of
Maximum Harvest Time, the machine senses a
refrigeration error. If the next cycle also produces a
refrigeration error, the machine Shuts Down.
Note: The last harvest cycle before shutting off on
bin full is 6 minutes long, unless the shut down
was initiated by a closed Bin Thermostat. In that
case the last harvest cycle will be normal.
The machine will not restart for 4 minutes after
switching off on Bin Full, unless the freeze button
is pressed.
Note: If during a Bin Full shut down, the machine
has not restarted for 12 hours, the compressor will
run for 30 seconds to clear its oil of refrigerant.
Continuous Run Time:
A unit that operates 24 hours a day 7 days a week
is too small for the user’s needs. To maintain
harvest integrity, the controller will extend the
harvest time up to 6 minutes every 15th
consecutive harvest cycle. Note: The length of this
harvest varies depending upon discharge temp.
Bin Thermostat (for those units so equipped):
In normal ambients the thermostat will react to ice
on the bulb in a few seconds. Reaction after
removal will take about a minute under normal
conditions, and longer in colder rooms.
Diagnostic Lights and Manual Resets
The controller will shut the machine off if a
malfunction is sensed. The Controller will restart
the machine 2 times, with a 50 minute interval
between restarts. If a malfunction is still present
after the second restart, the machine will then shut
off and must be manually reset. During the restart
interval, the machine will be off and a diagnostic
code indicated.
The exception to this is lack of water. The machine
will always try to re-fill the reservoir every 20
minutes.
Diagnostic Code Table
If a Diagnostic
Light
Water Light
Refrigeration
Light
Blinks once and
repeats
Water pump did
not start
Very long ice
harvest
Blinks twice and
repeats
Lack of water fill No harvest of
ice
Blinks three
times and
repeats
not used
High Discharge
Temperature
Is ON all the
time
Water valve
leaking thru
rapidly
Check for low
discharge
temperature or
long freeze
cycle
Both On all the
time
Check for thermistor set unplugged
or failed
Note: Diagnostic lights remain on until controller is
manually reset or until it successfully restarts the
machine.
CME306 & CME456
January 2000
Page 24