Electric Defrost Timer (Freezers)
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The defrost timer clock must be set to the correct time at initial start-up and after any power interruptions.
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Set the clock by rotating the clock face until the correct time is at the arrow on the face of the timer.
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The switch is programmed by pushing the captive trippers to the inner ring for the entire period the load is to be
turned "ON".
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When a tripper is pushed to the outside, the switch is in the "DEFROST" position.
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Each defrost tripper represents 15 minutes of defrost time.
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The timer is factory set for four defrost cycles daily at the following times: 4:00AM, 10:00AM, 4:00PM, and
10:00PM. Each defrost cycle is programmed for 30 minutes duration.
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The defrost times can be changed to initiate at periods of low activity.
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A setting of two to four defrost cycles per day is typical. For heavier frost loads, additional cycles may be required.
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The timer starts the defrost cycle automatically at the predetermined times.
NOTE: If the defrost termination thermostat fails to close, the fail safe setting on the timer will terminate the defrost cycle.
When the defrost cycle begins:
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The compressor and evaporator fan motors will stop.
The evaporator coil heaters will activate and increase the coil temperatures above 32°F/0°C, melting the frost and ice.
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NOTE: Walk-in temperatures will elevate above the set point during defrost cycles (30 minutes, 4 times per day)
but will return to the set point once the defrost cycle is complete.
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When the defrost time is complete or the evaporator coil warms to approximately 55°F/13°C, the compressor will
start the refrigeration cycle but the evaporator fan(s) will remain idle until the evaporator coil temperature is at or
below freezing.
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Once the evaporator coil temperature reaches approximately 30°F/-1°C, the evaporator fan(s) will activate.
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The system operates in the refrigeration cycle until another defrost cycle is initiated by the timer.
Air Defrost Timer (Coolers)
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The defrost timer is incorporated into the Air Defrost Thermostat. There is no separate Air Defrost Timer.
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The defrost timer is factory set for four defrost cycles daily at the following times: 4:00AM, 10:00AM, 4:00PM, and
10:00PM. Each defrost cycle is programmed for 30 minutes duration.
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The defrost times can be changed to initiate at periods of low activity.
Defrost Time Clock
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