Manitowoc QF0400 Service Manual

Also see for QC0700: Installation, use & care manual Service manual Building instructions Technician's handbook

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Manitowoc QF0400 Service Manual Manual pdf 58 page image

Troubleshooting Section 55-6 Part No. 80-1214-3Temperature is Too High or LowQF2200 OnlyThe temperature sensor (thermistor) is mounted on theliquid line. The temperature sensor provides input to thecontrol board. The control board monitors thetemperature anytime the liquid line solenoid valve isenergized.If the thermistor detects 123°F or higher for 15continuous seconds:1. The ice machine will de-energize the compressorand gear motor and initiate a SafeGuard Mode.2. The control board “Disch Temp” light will continue toflash twice then pause, to indicate the ice machinehas shut off on high temperature.3. The ice machine will remain off until the toggleswitch is moved from ICE to OFF, and back to ICE.orLine voltage is interrupted and restored.If the thermistor detects 30°F or less for 3continuous minutes:1. The control board ignores the low temperature limitfor the first 30 minutes of compressor run time.2. The ice machine will de-energize the liquid linesolenoid valve and gear motor, continuously flashthe control board “Disch Temp” light and initiate a60-minute Standby Mode.3. After the 60-minute Standby Mode, the ice machinewill de-energize the “Disch Temp” light and initiate astart-up sequence.4. After 30 minutes of compressor run time, the icemachine 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 minutesof run time:The ice machine will start another 60-minuteStandby Mode.If the liquid line temperature is 30°F or less for 3continuous minutes during 7 consecutive cycles the icemachine will start a SafeGuard Mode.During the SafeGuard Mode the ”Disch Temp” light willcontinually flash to indicate a Safeguard Mode. The icemachine remains off until:• The toggle switch is moved from ICE to OFF, thenback to ICE.• Line voltage is interrupted and restored.INDICATOR LIGHTBefore 48 hours have elapsed:After a Standby Mode has been initiated the ControlBoard “Disch Temp“ light will flash anytime the toggleswitch is placed in the OFF position.After 48 hours have elapsed:The SafeGuard will be automatically erased from memoryand the “Disch Temp” light will not flash.Temperature Sensor ChecklistQF2200Possible Problem List Corrective Action ListThermistor 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 andline 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 8/2003Downloaded from www.Manualslib.com manuals search engine