Fujitsu ASU7RLF1 Service Instructions Manual page 29

3. Defrost Flow Chart
The defrosting shall proceed by the integrating operation time, outdoor temperature
and outdoor heat exchanger temperature as follows.
・Tn - Tn10 < - 41°F(5°C)
・Tn - TnA < - 35.6°F(2°C)
However 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.
Heating operation start : Compressor ON
Normal defrost
O u s t d i e a r i e t m . p
4°F(-20°C) <
> 1 ° 4 ( F 1 - ° 0 C ) Outside air temp.
=
< 14°F(-10°C)
Outdoor HEX temp. Outdoor HEX temp.
< 1.4°F (-17°C) < Outside air temp.
=
=
-(30.6°F (17°C)) or
Outdoor HEX temp.
< -13°F (-25°C)
=
Outdoor HEX temp. : Over 53.6°F(12°C) for AOU18RLXFZH
Outdoor HEX temp. : Over 60.8°F(16°C) for AOU24RLXFZH
Compressor ON time : Maximum 15 minutes
Outside air temp.
=
> 4°F(-20°C)
Outdoor HEX temp.
< Outside air temp.
=
-(30.6°F (17°C)) or
Outdoor HEX temp.
< -22°F (-30°C)
=
Defrost start
Defrost Indicator:
[Operation lamp]
7 sec ON / 2 sec OFF
3 sec later Compressor : OFF
3 sec later Outdoor fan motor : OFF
28sec later 4WAY valve : OFF
34sec later Compressor : ON
or
Defrost end
01-26
Integrating defrost
Intermittent operation Continuous operation
Compressor Compressor
OFF count : integrating
40 times operation:
(Less than 10min.) Over 210 min.
When the
compressor is
s o t
outside air temp.
at 35.6°F(2°C)
p p e , d f I d e e t c e t d