ErrorCodeDoctor
Daikin Air Conditioner A4 error code
The A4 error means your Daikin air conditioner's freezing protection activated. This applies to water-cooled or hydronic indoor units and indicates a shortage of water volume, a low water temperature setting, or a defective water temperature thermistor. Contact a qualified technician to inspect the water circuit and thermistor.
Common causes
- Shortage of water volume in the water circuit
- Water temperature setting is too low
- Defective water temperature thermistor
How to fix it
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1
Contact a qualified technician to inspect the water volume, temperature settings, and thermistor
Related Daikin Air Conditioner error codes
A0
An external protection device connected to the indoor unit has been activated
A1
A fault was detected in the indoor unit PCB (control board)
A3
The drain level control system has detected an abnormality — drain may be clogged
A5
Freeze-up protection (cooling) or high pressure control (heating) has activated — check the air filter
A4 error — frequently asked questions
What does the A4 error mean on a Daikin air conditioner?
Freezing protection activated — low water temperature or insufficient water volume
What causes the A4 error?
The A4 error is usually caused by: Shortage of water volume in the water circuit; Water temperature setting is too low; Defective water temperature thermistor.
Can I fix the A4 error myself?
This is rated a hard fix — it often requires tools, parts, or experience, and may be safer left to a professional technician.
How much does it cost to fix the A4 error?
Fixing the A4 error on a Daikin air conditioner typically costs $80–$250, depending on parts and whether you do it yourself or hire a technician.
Is it safe to keep using my air conditioner with the A4 error?
We'd recommend addressing the A4 error before continuing to use the air conditioner, since hard-rated issues often involve a real fault rather than a minor glitch.