Daikin AC Error Code F5 — What It Means & How to Fix It

What Does This Error Mean?

F5 on a Daikin AC means the outdoor suction pipe temperature thermistor has a fault. This sensor monitors the temperature of the refrigerant returning to the compressor from the indoor unit. Abnormal suction temperature readings trigger F5 — the system stops to protect the compressor.

Affected Models

Daikin FTKF Series
Daikin FTKG Series
Daikin ATKF Series
Daikin Inverter Split AC (all models)
Daikin 1 Ton / 1.5 Ton / 2 Ton Inverter

Common Causes

Suction pipe thermistor failed — open or short circuit
Thermistor probe dislodged from the suction pipe on the outdoor unit
Wiring to the suction thermistor broken or corroded
Connector at the outdoor PCB loose or contaminated
Refrigerant level low — causing suction temperature to read abnormally

How to Fix It

Power off at the remote and circuit breaker. Wait 5 minutes and restart.

If F5 clears and stays away, it was a transient reading. If it returns, the sensor or refrigerant circuit needs inspection.
Check whether cooling performance dropped before F5 appeared.

Reduced cooling followed by F5 may indicate a refrigerant shortage rather than a sensor failure — both need a technician.
Call Daikin service — the technician will test the suction thermistor and check system pressures.

A refrigerant pressure check is a quick test that confirms whether the refrigerant circuit is healthy.

When to Call a Professional

F5 requires a Daikin authorised technician. If refrigerant level is low (also causing the F5 reading to be abnormal), only a licensed F-Gas technician can legally top up or repair the refrigerant circuit. Daikin India: 1800-103-3666.

Frequently Asked Questions

Can low refrigerant cause Daikin F5?

Yes — when refrigerant is low, the suction pipe temperature reads abnormally low (the refrigerant is too cold when it returns to the compressor). This abnormal reading can trigger F5 even if the thermistor itself is physically fine. A technician can distinguish between a sensor fault and a refrigerant issue by checking system pressures.