ICE MACHINES Q-Model Service Manual

Refrigeration System Section 7Pressure Control Specifications andDiagnosticsFAN 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, and openson a decrease in discharge pressure.SpecificationsModel Cut-In (Close) Cut-Out (Open)Q200/Q280Q320/Q370/Q420 250 psig ±5 200 psig ±5Q450/Q600Q800/Q1000Q1300/ Q1800275 psig ±5 225 psig ±5Check Procedure1. Verify fan motor windings are not open or grounded,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 Should Be: Fan Should Be:above cut-in 0 volts runningbelow cut-out line voltage offHIGH PRESSURE CUT-OUT (HPCO) CONTROLFunctionStops the ice machine if subjected to excessive highsidepressure.The HPCO control is normally closed, and opens on arise in discharge pressure.SpecificationsCut-out: 450 psig ±10Cut-in: Manual or automatic reset(Must be below 300 psig to reset).Check Procedure1. Set ICE/OFF/CLEAN switch to OFF, (Manual resetHPCO reset if tripped).2. Connect manifold gauges.3. Hook voltmeter in parallel across the HPCO, leavingwires attached.4. On water-cooled models, close the water servicevalve to the water condenser inlet. On self-containedair-cooled and remote models, disconnect the fanmotor.5. Set ICE/OFF/CLEAN switch to ICE.6. No water or air flowing through the condenser willcause 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, set ICE/OFF/CLEAN switch to OFF to stop ice machineoperation.Replace the HPCO control if it:• Will not reset (below 300 psig)• Does not open at the specified cut-out point7-32 Part No. 80-1100-3