A3 • Daikin • Altherma 3
Fault code A3 Daikin Altherma 3: causes and solution
A3 is often associated with a hydraulic circuit anomaly (depending on installation). The diagnosis aims to confirm correct circulation and the absence of air or sensor fault.
Proof status : Manufacturer reference needed for the exact range
Source: Daikin documentation (installer/service manual – according to product reference)
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Founder of AskMarcel.app. Sheets are written from manufacturer documentation; the reference is shown when it has been verified.
In brief
Fault code A3 on Daikin Altherma 3 means: A3 is often associated with a hydraulic circuit anomaly (depending on installation). The diagnosis aims to confirm correct circulation and the absence of air or sensor fault. Most common cause: A circulation fault, incorrect pressure, air in the circuit, or inconsistent measurement can trigger this type of code. First action: Check static pressure and restore to recommended level.. Call a registered engineer if the fault returns after basic checks or involves refrigerant work (F-Gas registered engineer required).
According to the Daikin installer reference guide (page 55), the A3 fault code on FTXJ AB9, AW9, and AS9 units specifically indicates an anomaly in the indoor unit's purge level control system.
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Daikin code A3: Marcel picks this code up for Altherma 3 and guides you, with the manufacturer reference when one exists.
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What does fault code A3 on Daikin mean?
A3 is often associated with a hydraulic circuit anomaly (depending on installation). The diagnosis aims to confirm correct circulation and the absence of air or sensor fault.
A circulation fault, incorrect pressure, air in the circuit, or inconsistent measurement can trigger this type of code.
Symptoms
- Heat pump stops during heating
- Circulation noise / cavitation
- Unstable flow and return temperatures
- Recurring fault code A3
Diagnosis
1. Check pressure and bleed air
- Check static pressure and restore to recommended level.
- Bleed air at high points and check the automatic air vent.
- Observe if stability improves after bleeding.
2. Check flow and hydraulic components
- Check filter, dirt separator, and isolation valves.
- Check the circulator (operation, speed, abnormal noise).
- Check balancing if multiple zones.
3. Check sensors and safety devices
- Check the fixing and wiring of the relevant sensors.
- Compare displayed values with an external measurement.
- Apply the manufacturer's procedure corresponding to the exact A3 code.
Repair and return to service — Daikin fault A3
Fault code A3 is often corrected by restoring circulation and bleeding air, then cleaning filter elements. If the code persists, follow specific Daikin checks (sensors/safety devices) for your installation.
When should you call an F-Gas engineer?
Contact an F-Gas registered engineer if the fault returns after basic checks, involves refrigerant charging, or requires PCB or compressor replacement on Daikin Altherma 3.
Affected models
- FTXJ AB9
- FTXJ AW9
- FTXJ AS9
Field context
This code appears when the indoor unit cannot correctly validate the purge level, potentially preventing the start or continuation of the normal operating cycle of the installation.
Frequently asked questions
What is the exact meaning of fault code A3 on these models?
Fault code A3 indicates an anomaly in the purge level control system within the indoor unit. This means the unit cannot correctly detect or manage the purge level, which is an internal control fault specific to this function.
Which models are affected by this fault?
According to the technical documentation provided, this fault code specifically affects the Daikin FTXJ AB9, FTXJ AW9, and FTXJ AS9 indoor unit ranges, where the purge level control system is involved.
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