Refrigeration System Section 77-16 Part Number 80-1480-3ANALYZING 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.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.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 ChecklistFreeze Cycle Discharge Pressure Low ChecklistNOTE: Do not limit your diagnosis to only the items listed in the checklists.Freeze CyclePSIG (kPa)Harvest CyclePSIG (kPa)Beginning of Cycle __________ __________Middle of Cycle __________ __________End of Cycle __________ __________Possible Cause Check/CorrectImproper installation See “Installation/Visual Inspection Checklist”Restricted condenser air flow (air-cooled models) High inlet air temperature (Self-Contained -110°F/43.3°C max.;Remote - 120°F/49°C max.)Condenser discharge air recirculationDirty condenser filterDirty condenserDefective fan cycling controlDefective fan motorRestricted condenser water flow (water-cooledmodels)Low water pressure [20 psi (138 kPa) min.]High inlet water temperature (90°F/32.2°C max.)Dirty condenserDirty/defective water regulating valveWater regulating valve out of adjustmentImproper refrigerant charge OverchargedNon-condensables in systemWrong type of refrigerantOther Non-Manitowoc components in systemHigh side refrigerant lines/component restricted (before mid-condenser)Defective head pressure control valve (remote models)Possible Cause Check/CorrectImproper installation See “Installation/Visual Inspection Checklist”Improper refrigerant charge UnderchargedWrong type of refrigerantWater regulating valve (water-cooled condensers) Out of adjustmentDefectiveOther Non-Manitowoc components in systemDefective head pressure control valve (remote models)Defective fan cycle control
