Fujitsu ASU30RLE Service Instruction page 26

3. Defrost Flow Chart
The defrosting shall proceed by the integrating operation time, outdoor temperature
and outdoor heat exchanger temperature as follows.
1st defrost
Compressor Compressor
integrating integrating
operation: operation:
Over 17 minutes Over 57 minutes
Tn < 15.8°F(- 9°C)
=
and Tn < 23°F(- 5°C)
=
Ta - Tn > 41°F(5°C)
= (and after 5 minutes
(and after 5 minutes
in the 23°F(- 5°C))
in the 41°F(5°C))
Heating operation start : Compressor ON
2nd and later defrost
Compressor
integrating
operation:
Over 35 minutes
①
Tn < -77°F(-25°C)
② Tn - Tn10 < -41°F(5°C)
( Tn < -42.8°F(6°C))
=
③ Tn - Tnb < -35.6°F(2°C)
( Tn < -42.8°F(6°C))
=
Defrost start
Defrost Indicator:
[Operation lamp]
6 sec ON / 2 sec OFF
Outdoor heat exchanger temperature: Over
or
Compressor ON time: Maximum 15 minutes
Defrost end
(Not defrosted for 10 minutes)
Integrating defrost
Compressor
integrating
operation:
Over 210 minutes
Tn < 26.6°F(- 3°C)
=
(and after 30 minutes
in the 26.6°F(- 3°C))
Tn : Outdoor heat exchanger temperature.
Ta : Outdoor temperature.
Tn10 : Temperature of continuous operation at 10 minutes.
Tnb : Back 5 minutes temperature.
Compressor : OFF
Outdoor fan motor : OFF
30 sec later 4-way valve : OFF
35 sec later compressor : ON
55° F(13°C)
01-22
Integrating defrost
( OFF count defrost )
Compressor
Compressor
integrating
OFF count :
operation:
40 times
Over 210 minutes
(Less than 10 minutes)
Tn < 23°F(- 5°C)
=
(and after 5 minutes
in the 23°F(- 5°C))