Manitowoc
Manitowoc Manitowoc
Suction Pressure Low ChecklistImproper Installation• Refer to “Installation and Visual InspectionChecklist” on page 104.Discharge Pressure• Discharge pressure is too low, and is affectingsuction pressure, refer to “Freeze Cycle DischargePressure Low Checklist”Improper Refrigerant Charge• Undercharged• Wrong type of refrigerantOther• Non-Manitowoc components in system• Improper water supply over evaporator refer to“Water System Checklist” on page 105.• Loss of heat transfer from tubing on back side ofevaporator• Restricted/plugged liquid line drier• Restricted/plugged tubing in suction side ofrefrigeration system• TXV starvingNOTE: Do not limit your diagnosis to only the itemslisted in the checklists.120 Part Number 80-01111-9 7/10
HOT GAS VALVEGeneralThe hot gas valve is an electrically operated valve thatopens when energized, and closes when deenergized.Normal OperationThe valve is de-energized (closed) during the freezecycle and energized (open) during the harvest cycle.The valve is positioned between the receiver and theevaporator and performs two functions:1. Prevents refrigerant from entering the evaporatorduring the freeze cycle.The hot gas valve is not used during the freezecycle. The hot gas valve is de-energized (closed)preventing refrigerant flow from the receiver intothe evaporator.2. Allows refrigerant vapor to enter the evaporator inthe harvest cycle.During the harvest cycle, the hot gas valve isenergized (open) allowing refrigerant gas from thedischarge line of the compressor to flow into theevaporator. The heat is absorbed by theevaporator and allows release of the ice slab.Exact pressures vary according to ambienttemperature and ice machine model. Harvestpressures (for Q130/Q170/Q210/Q270 ice machines)can be found in the Cycle Time/24 Hour IceProduction/ Refrigerant Pressure Charts in this book.Part Number 80-01111-9 7/10 121
- Page 70 and 71: WATER SHUTTERSThe water shutter is
- Page 72 and 73: SUMP DRAIN OVERFLOW TUBE1. Remove c
- Page 74 and 75: SPRAY BAR, WATER PUMP AND HOSE! War
- Page 76 and 77: ! WarningWear ru bber gloves an d s
- Page 78 and 79: WATER-COOLED ICE MACHINES1. Perform
- Page 80 and 81: HARVEST SEQUENCE5. HarvestThe water
- Page 82 and 83: ICE MAKINGSEQUENCE OFOPERATIONHarve
- Page 84 and 85: HARVEST SEQUENCE4. Harvest CycleThe
- Page 86 and 87: SM50INITIAL START-UP OR START-UP AF
- Page 88 and 89: ENERGIZED PARTS CHARTSM50Self-conta
- Page 90 and 91: Water Level CheckThe float valve is
- Page 92 and 93: QM20/QM30Routine adjustments and ma
- Page 94 and 95: 5. Remove the two screws holding th
- Page 96 and 97: Clean (Green)Pressing the “Clean
- Page 98 and 99: This Page Intentionally Left Blank9
- Page 100 and 101: DIAGNOSING ICE THICKNESS CONTROLCIR
- Page 102 and 103: Ice Machine Cycles Into Harvest Bef
- Page 104 and 105: INSTALLATION AND VISUAL INSPECTIONC
- Page 106 and 107: ICE FORMATION PATTERNEvaporator ice
- Page 108 and 109: SAFETY LIMIT FEATUREIn addition to
- Page 110 and 111: Safety Limit Notes• A safety limi
- Page 112 and 113: Safety Limit ChecklistThe following
- Page 114 and 115: Safety Limit #2Harvest time exceeds
- Page 116 and 117: Discharge Pressure High ChecklistIm
- Page 118 and 119: ProcedureStep1. Determine the ice m
- Page 122 and 123: Hot Gas Valve AnalysisThe valve can
- Page 124 and 125: FindingsThe inlet of the harvestval
- Page 126 and 127: DISCHARGE LINE TEMPERATURE ANALYSIS
- Page 128 and 129: REFRIGERATION COMPONENT DIAGNOSTICC
- Page 130 and 131: FINAL ANALYSISThe column with the h
- Page 132 and 133: Q130/Q170/Q210/Q270 Ice Machines On
- Page 134 and 135: QM20/QM30DIAGNOSING AN ICE MACHINET
- Page 136 and 137: QM30The QM30 ice machines have a ve
- Page 138 and 139: Ice Production CheckThe QM20/QM30 d
- Page 140 and 141: REFRIGERATION DIAGNOSTICSImportant:
- Page 142 and 143: 5. Install thermometer thermocouple
- Page 144 and 145: SM50DIAGNOSING AN ICE MACHINETHAT W
- Page 146 and 147: ICE QUALITY IS POOR — CUBES ARE S
- Page 148 and 149: ICE MACHINE RUNS AND NO ICE IS PROD
- Page 150 and 151: DISCHARGE PRESSURE HIGH CHECKLISTIm
- Page 152 and 153: ProcedureStep1. Determine the ice m
- Page 154 and 155: Other• Non-Manitowoc components i
- Page 156 and 157: FindingsThe inlet of the harvestval
- Page 158 and 159: ADJUSTING CUBE WEIGHTThe cube weigh
- Page 160 and 161: Bin SwitchQM45/Q130/Q170/Q210/Q270F
- Page 162 and 163: Bin Switch Removal — QM45/Q1301.
- Page 164 and 165: Bin ThermostatQM20/QM30FunctionThe
- Page 166 and 167: SM50FunctionThe bin thermostat stop
- Page 168 and 169: Check Procedure! WarningHigh (line)
Suction Pressure Low ChecklistImproper Installation• Refer to “Installation and Visual InspectionChecklist” on page 104.Discharge Pressure• Discharge pressure is too low, and is affectingsuction pressure, refer to “Freeze Cycle DischargePressure Low Checklist”Improper Refrigerant Charge• Undercharged• Wrong type of refrigerantOther• Non-<strong>Manitowoc</strong> components in system• Improper water supply over evaporator refer to“Water System Checklist” on page 105.• Loss of heat transfer from tubing on back side ofevaporator• Restricted/plugged liquid line drier• Restricted/plugged tubing in suction side ofrefrigeration system• TXV starvingNOTE: Do not limit your diagnosis to only the itemslisted in the checklists.120 Part Number 80-01111-9 7/10
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