ICE MACHINES Q-Model Service Manual

Section 7Refrigeration SystemANALYZING DISCHARGE PRESSUREDURING FREEZE OR HARVEST CYCLEProcedure1. Determine the ice machine operating conditions:Air temp. entering condenser ______Air temp. around ice machine ______Water temp. entering sump trough ______2. Refer to Operating Pressure Chart for ice machinebeing checked. (These charts begin on Page 7-33.)Use the operating conditions determined in step 1 tofind the published normal discharge pressures.Freeze Cycle _______ Harvest Cycle_______3. Perform an actual discharge pressure check.FreezeCycle PSIGHarvestCycle PSIGBeginning of Cycle __________ __________Middle of Cycle __________ __________End of Cycle __________ __________4. Compare the actual discharge pressure (step 3) withthe published discharge pressure (step 2).The discharge pressure is normal when the actualpressure falls within the published pressure range for theice machine’s operating conditions.Freeze Cycle Discharge Pressure High ChecklistPossible CauseCheck/CorrectImproper installation See “Installation/Visual Inspection Checklist” on Page 7-10Restricted condenser air flow (air-cooled models) High inlet air temperature (110°F/43.3°C max.)Condenser discharge air recirculationDirty condenser filterDirty condenser finsDefective fan cycling controlDefective fan motorRestricted condenser water flow (water-cooledmodels)Improper refrigerant chargeOtherFreeze Cycle Discharge Pressure Low ChecklistLow water pressure (20 psi min.)High inlet water temperature (90°F/32.2°C max.)Dirty condenserDirty/defective water regulating valveWater regulating valve out of adjustmentOverchargedNon-condensables in systemWrong type of refrigerantNon-Manitowoc components in systemHigh side refrigerant lines/component restricted (before mid-condenser)Defective head pressure control valve (remote models)Possible CauseCheck/CorrectImproper installation See “Installation/Visual Inspection Checklist” on Page 7-10Improper refrigerant chargeUnderchargedWrong type of refrigerantWater regulating valve (water-cooled condensers) Out of adjustmentDefectiveOtherNon-Manitowoc components in systemDefective head pressure control valve (remote models)Defective fan cycle controlNOTE: Do not limit your diagnosis to only the items listed in the checklists.Part No. 80-1100-3 7-17