Section 7Refrigeration System7-30Pressure Control Specifications and DiagnosticsFAN CYCLE CONTROL(Self-Contained Air-Cooled Models Only)FunctionCycles the fan motor on and off to maintain properoperating discharge pressure.The fan cycle control closes on an increase, andopens on a decrease in discharge pressure.SpecificationsModel Cut-In (Close) Cut-Out (Open)J200 J250J320 J420J450 J600250 psig ±5 200 psig ±5J800 J1000J1300 J1800 275 psig ±5 225 psig ±5Check Procedure1. Verify fan motor windings are not open orgrounded, and fan spins freely.2. Connect manifold gauges to ice machine.3. Hook voltmeter in parallel across the fan cyclecontrol, leaving wires attached.4. Refer to chart below.At: Reading ShouldBe:Fan ShouldBe:above cut-in 0 volts runningbelow cut-out line voltage offHIGH PRESSURE CUTOUT(HPCO) CONTROLFunctionStops the ice machine if subjected to excessive high-side pressure.The HPCO control is normally closed, and opens on arise in discharge pressure.SpecificationsCut-out: 450 psig ±10Cut-in: Manual (below 300 psig to reset)Check Procedure1. Set ICE/OFF/CLEAN switch to OFF, and resetHPCO if tripped.2. Connect manifold gauges.3. Hook voltmeter in parallel across the HPCO,leaving wires attached.4. On water-cooled models, close the water servicevalve to the water condenser inlet. On self-contained air-cooled and remote models,disconnect the fan motor.5. Set ICE/OFF/CLEAN switch to ICE.6. No water or air flowing through the condenserwill cause the HPCO control to open because ofexcessive pressure. Watch the pressure gauge andrecord the cut-out pressure.WARNINGIf discharge pressure exceeds 460 psig and theHPCO control does not cut out, setICE/OFF/CLEAN switch to OFF to stop icemachine operation.Replace the HPCO control if it:• Will not reset (below 300 psig)• Does not open at the specified cut-out point
