Defrost Operation Control - Fujitsu R410A Service Instruction

23. DEFROST OPERATION CONTROL

23. DEFROST OPERATION CONTROL
1. CONDITION OF STARTING THE DEFROST OPERATION
The defrost operation starts as shown in the following Table 18, 19, 20 and 21.
( Table 18 : Condition of 1st defrost operation )
1st defrost
after
starting operation
( Table 19 : Condition of 2nd defrost operation )
From 2nd and later
defrost after
starting operation
( Table 20 : Condition of Integrating defrost operation )
Integrating defrost
( Table 21 : Condition of Integrating ( OFF count ) defrost operation )
Integrating defrost
( OFF count 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 becomes as shown in Table 22.
( Table 22 : Condition of defrost release )
Outdoor heat exchanger temperature is higher than 55.4°F(13°C)
Compressor operation time has passed 15 minutes.
Compressor integrating operation time Compressor integrating operation time
Less than 17 minutes
Does not operate
(and after 5 minutes, in the 41°F(5°C))
Compressor integrating operation time
Less than 35 minutes
Does not operate
Compressor integrating operation time
More than 210 minutes
( For long continuous operation )
Tn < 26.6°F(-3°C)
=
(and after 30 minutes, if the 26.6°F (-3°C))
Compressor integrating operation time
Less than 10 minutes
( For intermittent operation )
OFF count of the compressor : 40 times
Release Condition
or
More than 17 minutes
Tn < 15.8°F(-9°C)
=
and
Ta - Tn > 41°F(5°C)
=
Tn : Outdoor heat exchanger temperature.
Ta : Outdoor temperature.
More than 35 minutes
Tn < -77°F (-25°C)
=
Tn - Tn10 < -41°F (5°C) ( Tn < -42.8°F (6°C))
Tn - Tnb < -35.6°F (2°C) ( Tn < -42.8°F (6°C))
Tn10 : Temperature of continuous operation at 10 minutes.
Tnb : Back 5 minutes temperature.
More than 210 minutes
( For long continuous operation )
Tn < 23°F(-5°C)
(and after 5 minutes, if the 23°F (-5°C))
01-15
More than 57 minutes
Tn < 23°F(-5°C)
=
(and after 5 minutes, if the 23°F (-5°C))
=
=
=