Manitowoc QF0400 Service Manual

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

Contents

Manitowoc QF0400 Service Manual Manual pdf 57 page image

Section 5 TroubleshootingPart No. 80-1214-3 5-5Temperature is Too High or LowQF400/QC700/QF800The temperature sensor (thermistor) is mounted on thecompressor discharge line. The temperature sensorprovides input to the control board. The control boardmonitors the temperature anytime the compressor isenergized.If the thermistor detects 245°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 155°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 compressorand gear motor, continuously flash the control board“Disch Temp” light and initiate a 60-minute StandbyMode.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 discharge line temperature.Discharge line temperature normal:The ice machine continues to make ice.Discharge line temperature below 155°F after 30minutes of run time:The ice machine will start another 60-minuteStandby Mode.If the discharge line temperature drops below 155°F for3 continuous minutes during 7 consecutive cycles theice machine 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 ChecklistQF400/QC700/QF800Possible Problem List Corrective Action ListThermistor is not properly insulated Insulate thermistor.Thermistor loose Secure thermistor to discharge line.Thermistor mounted in the wrong location Position thermistor on discharge line 6 in. from compressordischarge port.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).Defective compressor Replace compressor.Insufficient or low water pressure Verify water pressure is between 20 and 80 psig.Revised 8/2003Downloaded from www.Manualslib.com manuals search engine