Fujitsu ASU18RLF Service Instructions Manual page 17

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
integrating
operation:
Over 22 minutes
Outdoor
Outdoor
heat exchanger
heat exchanger
temperature:
temperature:
Below 23°F(- 5°C)
Below 15.8°F(- 9°C)
Heating operation start : Compressor ON
2nd and later defrost
Compressor Compressor
integrating integrating
operation: operation:
Over 62 minutes Over 35 minutes
Outdoor
heat exchanger
temperature:
Below 21.2°F(- 6°C)
Defrost Indicator:
[Operation lamp]
7 sec ON / 2 sec OFF
Outdoor heat exchanger temperature: Over 55° F(13°C)
Compressor ON time: Maximum 15 minutes
(Not defrosted for 10 minutes)
Defrost start
Compressor : OFF
Outdoor fan motor : OFF
30 sec later 4-way valve : OFF
35 sec later compressor : ON
or
Defrost end
01-14
Integrating defrost
(Constant monitoring)
Compressor
Compressor
integrating
OFF count :
operation:
40 times
Over 210 minutes
Outdoor
heat exchanger
temperature:
Below 26.6°F(- 3°C)