Service manual

Refrigeration System Section 7
7-10
Part No. 80-1206-3
SAFETY LIMITS
General
In addition to standard safety controls, such as high
pressure cut-out, the control board has two built in safety
limit controls which protect the ice machine from major
component failures. There are two control boards with
different safety limit sequences. The microprocessor
chip can identify the control boards. Current production
control boards have an orange label on the control board
microprocessor. The earlier version does not have the
orange label.
Safety Limit #1: If the freeze time reaches 60 minutes,
the control board automatically initiates a harvest cycle.
Control Board With Black Microprocessor
If 3 consecutive 60-minute freeze cycles occur, the ice
machine stops.
Control Board With Orange Label On Microprocessor
If 6 consecutive 60-minute freeze cycles occur, the ice
machine stops.
Safety Limit #2: If the harvest time reaches 3.5
minutes, the control board automatically returns the ice
machine to the freeze cycle.
Control Board With Black Microprocessor
If 3 consecutive 3.5 minute harvest cycles occur, the ice
machine stops.
Control Board With Orange Label On Microprocessor
If 500 consecutive 3.5 minute harvest cycles occur, the
ice machine stops.
Safety Limit Stand-By Mode:
(QDUALC ONLY)
The first time a safety limit shut down occurs, (three
consecutive long freeze or harvest cycles) the ice
machine will turn off for 60 minutes (Stand-by Mode).
During the Stand-by Mode the harvest light will be
flashing continuously and a safety limit indication can be
viewed. After 60 minutes the ice machine will
automatically restart to see if the problem re-occurs. If
the same safety limit is reached a second time (three
more consecutive long freeze or harvest cycles) the ice
machine will initiate a safety limit shut down and remain
off until it is manually restarted. During a safety limit shut
down the harvest light will be flashing continuously.