ICE MACHINES Q-Model Service Manual

Ice Machine Sequence of Operation Section 4HARVEST SEQUENCE5. Water PurgeThe water pump continues to run, and the water dumpvalve energizes for 45 seconds to purge the water in thesump trough. The water fill valve energizes (turns on)and de-energizes (turns off) strictly by time. The water fillvalve energizes for the last 15 seconds of the 45-secondwater purge. The water purge must be at the factorysetting of 45 seconds for the fill valve to energize duringthe last 15 seconds of the Water Purge. If set at lessthan 45 seconds the water fill valve does not energizeduring the water purge.After the 45 second water purge, the water fill valve,water pump and dump valve de-energize. (Refer to“Water Purge Adjustment” on Page 3-3 for details.) Theharvest valve(s) and HPR solenoid valve also open atthe beginning of the water purge.6. HarvestThe HPR valve and the harvest valve(s) remain openand the refrigerant gas warms the evaporator causingthe cubes to slide, as a sheet, off the evaporator and intothe storage bin. The sliding sheet of cubes swings thewater curtain out, opening the bin switch. Themomentary opening and re-closing of the bin switchterminates the harvest sequence and returns the icemachine to the freeze sequence (Step 3 - 4.)AUTOMATIC SHUT-OFF7. Automatic Shut-OffWhen the storage bin is full at the end of a harvestsequence, the sheet of cubes fails to clear the watercurtain and will hold it open. After the water curtain isheld open for 7 seconds, the ice machine shuts off. Theice machine remains off for 3 minutes before it canautomatically restart.The ice machine remains off until enough ice has beenremoved from the storage bin to allow the ice to dropclear of the water curtain. As the water curtain swingsback to the operating position, the bin switch re-closesand the ice machine restarts (steps 1 - 2) provided the 3minute delay period is complete.Figure 4-6. Automatic Shut-Off (Typical Q450Shown)Figure 4-5. Harvest Sequence (Typical Q450 Shown)4-4 Part No. 80-1100-3