Manitowoc QD0202A, Service Manual

Page: 127 / 175

Section 7 Refrigeration System
Part No. 80-1100-3
7-15
Safety Limit #1
Refer to page 7-13 for control board identification and safety limit operation.
Control Board with Black Microprocessor - Freeze Time exceeds 60 minutes for 3 consecutive freeze cycles
or
Control Board with Orange Label on Microprocessor - Freeze time exceeds 60 minutes for 6 consecutive freeze
cycles .
SAFETY LIMIT NOTES
• Because there are many possible external problems,
do not limit your diagnosis to only the items listed in
this chart.
• A continuous run of 100 harvests automatically
erases the safety limit code.
• The control board will store and indicate only one
safety limit – the last one exceeded.
• If the toggle switch is moved to the OFF position and
then back to the ICE position prior to reaching the
100-harvest point, the last safety limit exceeded will
be indicated.
• If the harvest light did not flash prior to the ice
machine restarting, then the ice machine did not stop
because it exceeded a safety limit.
Possible Cause Check/Correct
Improper installation See “Installation/Visual Inspection Checklist” on Page 7-10
Water system Low water pressure (20 psi min.)
High water pressure (80 psi max.)
High water temperature (90°F/32.2°C max.)
Clogged water distribution tube
Dirty/defective water fill valve
Dirty/defective water dump valve
Defective water pump
Electrical system Ice thickness probe out of adjustment
Harvest cycle not initiated electrically
Contactor not energizing
Compressor electrically non-operational
Restricted condenser
air flow (air-cooled models)
High inlet air temperature (110°F/43.3°C max.)
Condenser discharge air recirculation
Dirty condenser filter
Dirty condenser fins
Defective fan cycling control
Defective fan motor
Restricted condenser water flow (water-cooled models) Low water pressure (20 psi min.)
High water temperature (90°F/32.2°C max.)
Dirty condenser
Dirty/defective water regulating valve
Water regulating valve out of adjustment
Refrigeration system Non-Manitowoc components
Improper refrigerant charge
Defective head pressure control (remotes)
Defective harvest valve
Defective compressor
TXV starving or flooding (check bulb mounting)
Non-condensables in refrigeration system
Plugged or restricted high side refrigerant lines or component