Off Defrost Operation Control - Fujitsu ASU18RLQ Service Instructions Manual

20. OFF DEFROST OPEARTION CONTROL
When operation stops in the [Heating operation] mode, if frost is adhered to the outdoor unit heat
exchanger, the defrost operation will proceed automatically. In this time, if indoor unit operation
lamp flashes slowly (7 sec ON / 2 sec OFF), the outdoor unit will allow the heat exchanger to defrost,
and then stop.
(1). OFF DEFROST OPERATION CONDITION
In heating operation, the outdoor heat exchanger temperature is less than - 25°F(-4°C), and
compressor operation integrating time lasts for more than 30 minutes.
(2). OFF DEFROST END CONDITION
Outdoor heat exchanger temperature sensor value is higher than 50°F(10°C) or
ASU15/18RLQ
Compressor operation time has passed 15 minutes.
OFF Defrost Flow Chart
Release Condition
Heating operation stop
Outdoor heat exchanger temperature:
Below - 25°F(-4°C)
and
Compressor integrating operation:
Over 30 minutes
Defrost start
Defrost Indicater:
[Operation lamp]
7 sec ON / 2 sec OFF
Outdoor heat exchanger temperature:
Over 50°F(10°C)
or
Compressor ON time:
Over 15 minutes
Defrost end
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