Off Defrost Operation Control - Fujitsu R410A Service Instruction

24. OFF DEFROST OPERATION 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 24.8°F(-4°C), and
compressor operation integrating time lasts for more than 30 minutes.
2. OFF DEFROST RELEASE CONDITION
OFF defrost operation is released when the conditions becomes as shown in Table 23.
( Table 23 : OFF Defrost Release Condition )
Outdoor heat exchanger temperature is higher than 55.4°F(13°C)
Compressor operation time has passed 10 minutes.
OFF Defrost Flow Chart
Outdoor heat exchanger temperature :
Below
Compressor integrating operation :
Over 30 minutes
Outdoor heat exchanger temperature : Over
Compressor ON time : Maximum 10 minutes
Release Condition
or
Heating operation stop
24.8°F(
-4°C)
and
Defrost start
Defrost Indicator:
[Operation lamp]
7 sec ON / 2 sec OFF
55.4°F(
or
Defrost end
01-17
13°C)