Section 4 Ice Machine Sequence of Operation4-1Section 4 Basic Ice Machine Sequence of OperationSelf-Contained Air- and Water-CooledJ200/J250/J320/J420/J450/J600/J800/J1000/J1300/J1800INITIAL START-UP ORSTART-UP AFTER AUTOMATIC SHUT-OFF1. Water PurgeBefore the compressor starts, the water pump andwater dump solenoid are energized for 45 seconds, tocompletely purge the ice machine of old water. Thisfeature ensures that the ice making cycle starts withfresh water.The hot gas valve(s) is also energized during waterpurge, although it stays on for an additional 5 seconds(50 seconds total on time) during the initialrefrigeration system start-up.2. Refrigeration System Start-UpThe compressor starts after the 45 second waterpurge, and it remains on throughout the entire Freezeand Harvest Sequences. The hot gas valve(s) remainson for 5 seconds during initial compressor start-upand then shuts off.At the same time the compressor starts, the fancondenser motor (air-cooled models) is supplied withpower throughout the entire Freeze and HarvestSequences. The fan motor is wired through a fancycle pressure control, therefore it may cycle on andoff. (The compressor and condenser fan motor arewired through the contactor. As a result, anytime thecontactor coil is energized, the compressor and fanmotor are supplied with power.)FREEZE SEQUENCE3. PrechillThe compressor is on for 30 seconds prior to waterflow, to prechill the evaporator.4. FreezeThe water pump restarts after the 30 second prechill.An even flow of water is directed across theevaporator and into each cube cell, where it freezes.When sufficient ice has formed, the water flow (notthe ice) contacts the ice thickness probe. Afterapproximately 7 seconds of continual water contact,the harvest sequence is initiated. The ice machinecannot initiate a harvest sequence until a 6 minutefreeze lock has been surpassed.Freeze Sequence (Typical J450 Shown)Continued on next page...
