Defrost Operation Control - Fujitsu ASU7RLF1 Service Instructions Manual

25. DEFROST OPERATION CONTROL

1. CONDITION OF STARTING THE DEFROST OPERATION
The defrost operation starts when the outdoor heat exchanger temperature sensor detects
the temperature lower than the values shown in Table 16, 17 .
1-1 NORMAL DEFROST
( Table 16 : Condition of starting defrost operation )
Normal defrost
Less than 35 minutes
Does not operate
1-2. INTEGRATING DEFROST
( Table 17 : Condition of starting defrost operation )
Integrating defrost
If the compressor continuous operation time is less than 10 minutes,
the OFF number of the compressor is counted.
If any defrost operated, the compressor OFF count is cleared.
2. CONDITION OF THE DEFROST OPERATION COMPLETION
Defrost operation is released when the conditions become as shown in Table 18 .
For AOU18RLXFZH
( Table 18-1 : Defrost release condition )
Outdoor heat exchanger temperature sensor value is higher than 53.6°F(12°C) or
Compressor operation time has passed 15 minutes.
For AOU24RLXFZH
( Table 18-2 : Defrost release condition )
Outdoor heat exchanger temperature sensor value is higher than 60.8°F(16°C) or
Compressor operation time has passed 15 minutes.
Compressor integrating operation time
Outdoor heat exchanger temp. < 1.4°F(-17°C)
(at outside air temp. > 14°F(-10°C)
Outdoor heat exchanger temp. < Outside air temp.-(30.6°F(17°C))
or Outdoor heat exchanger temp. < -13°F(-25°C)
(at 4°F(-20°C) < outside air temp. < 14°F(-10°C))
Outdoor heat exchanger temp. < Outside air temp.-(30.6°F(17°C))
or Outdoor heat exchanger temp. < -22°F(-30°C)
(at outside air temp. < 4°F(-20°C))
Tn - Tn10 < - 41°F(5°C) but Tn < 42.8°F(- 6°C)
(Outdoor heat exchanger temp. detected for every 5 minutes )
Tn - TnA < - 35.6°F(2°C) but Tn < 42.8°F(- 6°C)
(Outdoor heat exchanger temp. detected for every 5 minutes )
Tn : Outdoor heat exchanger temp.
Tn10 : Temperature of continuous operation at 10 minutes.
TnA : Back 5 minutes temperature.
Compressor integrating operation time
More than 210 minutes
( For continuous operation )
When the compressor is
stopped, If detected
outside air temp. at 35.6°F(2°C)
Release Condition
Release Condition
More than 35minutes
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Less than 10 minutes
( For intermittent operation )
OFF count of the compressor
40 times
( at outside air temp. < 35.6°F(2°C))
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