Daikin FTXS09HVJU, Service Manual

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SiUS04-904 Troubleshooting
100 Service Diagnosis
4.3 Freeze-up Protection Control or High Pressure Control
Remote
Controller
Display
A5
Method of
Malfunction
Detection

High pressure control
During heating operations, the temperature detected by the indoor heat exchanger thermistor is
used for the high pressure control (stop, outdoor fan stop, etc.)

Freeze-up protection control (operation halt) is activated during cooling operation according to
the temperature detected by the indoor unit heat exchanger thermistor.
Malfunction
Decision
Conditions

High pressure control
During heating operations, the temperature detected by the indoor heat exchanger thermistor is
above 149°F
(65°C)

Freeze-up protection
When the indoor unit heat exchanger temperature is below 32°F (0°C) during cooling operation.
Supposed
Causes

Operation halt due to clogged air filter of the indoor unit.

Operation halt due to dust accumulation on the indoor unit heat exchanger.

Operation halt due to short-circuit.

Detection error due to faulty indoor unit heat exchanger thermistor.

Detection error due to faulty indoor unit PCB.