Defrost (Time Initiated -Temperature Terminated)

After a run period of approximately 6 hours, the evaporator coil will be frosted and require a defrost. Four defrost cycles per day are programmed at the factory (4 a.m., 10 a.m., 4 p.m., and 10 p.m.). It may be necessary to change the defrost cycle times to fit your work schedule.

The interior temperature may rise 10-20? F during the defrost cycle. Do not be alarmed. No thawing of the product will occur. Soon after the cycle is complete, the unit will return to proper temperature.

The defrost sequence is as follows:

1. Timer starts defrost cycle.



2. Liquid line solenoid valve closes, evaporator fans stop, and the defrost heaters are energized.



3. After pumping down, the compressor stops.



4. The heaters warm the coil, melt the frost, and trip the termination thermostat at the set temperature.



5. The defrost cycle is terminated; the liquid line solenoid opens; and defrost heaters are de-energized.



6. The pressure switch closes and the compressor starts the refrigeration cycle.



7. The evaporator fans will remain off until the coil temperature reaches approximately 20°F.

Should the termination thermostat fail to end the defrost, the timer fail safe time is designed to end after 30 minutes.

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