Manitowoc Ice FLAKE/CHIPLET QF0400 - Manual (Page 58)

Troubleshooting Section 5
5-6 Part No. 80-1214-3
Temperature is Too High or Low
QF2200 Only
The temperature sensor (thermistor) is mounted on the
liquid line. The temperature sensor provides input to the
control board. The control board monitors the
temperature anytime the liquid line solenoid valve is
energized.
If the thermistor detects 123°F or higher for 15
continuous seconds:
1. The ice machine will de-energize the compressor
and gear motor and initiate a SafeGuard Mode.
2. The control board “Disch Temp” light will continue to
flash twice then pause, to indicate the ice machine
has shut off on high temperature.
3. The ice machine will remain off until the toggle
switch is moved from ICE to OFF, and back to ICE.
or
Line voltage is interrupted and restored.
If the thermistor detects 30°F or less for 3
continuous minutes:
1. The control board ignores the low temperature limit
for the first 30 minutes of compressor run time.
2. The ice machine will de-energize the liquid line
solenoid valve and gear motor, continuously flash
the control board “Disch Temp” light and initiate a
60-minute Standby Mode.
3. After the 60-minute Standby Mode, the ice machine
will de-energize the “Disch Temp” light and initiate a
start-up sequence.
4. After 30 minutes of compressor run time, the ice
machine will check the liquid line temperature.
Liquid line temperature normal:
The ice machine continues to make ice.
Liquid line temperature 30°F or less after 30 minutes
of run time:
The ice machine will start another 60-minute
Standby Mode.
If the liquid line temperature is 30°F or less for 3
continuous minutes during 7 consecutive cycles the ice
machine will start a SafeGuard Mode.
During the SafeGuard Mode the ”Disch Temp” light will
continually flash to indicate a Safeguard Mode. The ice
machine remains off until:
• The toggle switch is moved from ICE to OFF, then
back to ICE.
• Line voltage is interrupted and restored.
INDICATOR LIGHT
Before 48 hours have elapsed:
After a Standby Mode has been initiated the Control
Board “Disch Temp“ light will flash anytime the toggle
switch is placed in the OFF position.
After 48 hours have elapsed:
The SafeGuard will be automatically erased from memory
and the “Disch Temp” light will not flash.
Temperature Sensor Checklist
QF2200
Possible Problem List Corrective Action List
Thermistor is not properly insulated Insulate thermistor.
Thermistor loose Secure thermistor to liquid line.
Thermistor mounted in the wrong location Position thermistor on liquid line between heat exchanger and
line drier.
Thermistor defective Refer to CHECK PROCEDURE under “Thermistor.”
Flooding expansion valve Replace expansion valve.
Refrigerant overcharge or undercharge Recover and weigh in nameplate charge.
Low ambient temperature Verify ambient temperature remains above 45°F (7.2°C).
Headmaster will not bypass Replace headmaster.
Insufficient or low water pressure Verify water pressure is between 20 and 80 psig.
Revised 8/2003