Defrost Operation Control - Fujitsu ASU 9RLF1 Service Instruction

21. DEFROST OPERATION CONTROL

1. CONDITION OF STARTING THE DEFROST OPERATION
The defrost operation starts as shown in the following Table 20.
(Table 20 : Condition of starting Defrost Operation)
Normal defrost
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 21.
(Table 21 : Defrost Release Condition)
Outdoor heat exchanger temperature sensor value is higher than 60.8
Compressor operation time has passed 15 minutes.
Less than 25 minutes
Does not operate
More than 240 minutes
(For continuous operation)
Outdoor heat exchanger
temperature below 26.6°F(-3°C)
Release Condition
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.-(12.6°F (7°C))
or Outdoor heat exchanger temp.< -13°F (-25°C)
(at -4°F (-20°C)< Outdoor air temp.< 14°F (-10°C)
=
Outdoor heat exchanger temp. < Outside air temp.-(12.6°F (7°C))
or Outdoor heat exchanger temp. < -22°F(- 30°C)
(at outside air temp. < -4°F(-20°C))
Compressor integrating operation time
More than 213 minutes
(For continuous operation)
Outdoor heat exchanger
temperature below 23°F(-5°C)
01-15
More than 25 minutes
=
=
=
=
=
Less than 10 minutes
( For intermittent operation )
OFF count of the compressor
40 times
16°C) or
°F(