Daikin FDMQ12RVJU, Service Manual

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SiUS091601EA Troubleshooting for FTX, FVXS Series
Part 6 Service Diagnosis 126
5.2 Freeze-up Protection Control/Heating Peak-cut Control
Error Code
A5
Method of Error
Detection
 Freeze-up protection control
During cooling operation, the freeze-up protection control (operation halt) is activated according
to the temperature detected by the indoor heat exchanger thermistor.
 Heating peak-cut control
During heating operation, the temperature detected by the indoor heat exchanger thermistor is
used for the heating peak-cut control (operation halt, outdoor fan stop, etc.)
Error Decision
Conditions
 Freeze-up protection control
During cooling operation, the indoor heat exchanger temperature is below 0°C (32°F).
 Heating peak-cut control
During heating operation, the indoor heat exchanger temperature is above 59 ~ 60°C (138.2 ~
140°F).
Supposed
Causes
 Short-circuited air
 Clogged air filter of the indoor unit

Dust accumulation on the indoor heat exchanger
 Defective indoor heat exchanger thermistor
 Defective indoor unit PCB
Troubleshooting
NO
NO
NO
Check No. 01
Check the indoor heat exchanger
thermistor.
YES
YES
(R21064)
YES
YES
NO
Caution
Provide sufficient air passage.
Clean the air filter.
Clean the indoor heat
exchanger.
Replace the indoor unit PCB
(control PCB).
Replace the indoor heat
exchanger thermistor.
As
described in the
thermistor characteristic
chart?
Check the air filter.
Check the dust accumulation on
the indoor heat exchanger.
Is there any short circuit?
Dirty?
Dirty?
Check the air passage.
Be sure to turn off the power switch before connecting or disconnecting
connectors, or parts may be damaged.