ñ89ñProcedureStep Example UsingQY0454A Model Ice Machine1. Determine the icemachine operatingconditions.Air temp. entering condenser:90∞F/32.2∞CAir temp. around ice machine:80∞F/26.7∞CWater temp. entering water fill valve:70∞F/21.1∞C2A. Refer to ìCycle Timeî andìOperating Pressureîcharts for ice machinemodel being checked.Using operatingconditions from step 1,determine publishedFreeze cycle time andpublished Freeze cyclesuction pressure.13.7-14.1 minutesPublished Freeze cycle time:55-36 psigPublished Freeze cycle suction pressure:2B. Compare the publishedFreeze cycle time andpublished Freeze cyclesuction pressure. Developa chart.Published Freeze Cycle Time(minutes)Published Freeze Cycle SuctionPressure (psig)In the example, the proper suction pressureshould be approximately 44 psig at 7 minutes;41 psig at 9 minutes; etc.3. Perform an actual suctionpressure check at thebeginning, middle and endof the Freeze cycle. Notethe times at which thereadings are taken.Manifold gauges were connected to theexample ice machine and suction pressurereadings taken as follows:psigBeginning of Freeze cycle: 59 (at 1 min.)Middle of Freeze cycle: 48 (at 7 min.)End of Freeze cycle: 40 (at 14 min.)4. Compare the actualFreeze cycle suctionpressure (step 3) to thepublished Freeze cycletime and pressurecomparison (step 2B).Determine if the suctionpressure is high, low oracceptable.In this example, the suction pressure isconsidered high throughout the Freezecycle. It should have been:Approximately 55 psig(at 1 minute) ñ not 59Approximately 44 psig(at 7 minutes) ñ not 48Approximately 36 psig(at 14 minutes) ñ not 401 3 5 7 9 12 1455 52 48 44 41 38 36
