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Daikin Altherma fault UA-00

Indoor unit, outdoor unit mismatching problem

Heat pump

What it means

Signal transmission between outdoor and indoor unit abnormality. Improper combination of outdoor and indoor unit.

Likely causes

  1. Improper combination of the indoor unit and the outdoor unit
  2. Faulty wiring between the outdoor unit, indoor unit and domestic hot water tank
  3. Faulty main PCB
  4. Faulty hydro PCB
  5. Damaged or broken wires between power supply terminal and hydro PCB
  6. Incorrectly connected wires

Where to start

  1. Check for improper combination of the indoor unit and the outdoor unit using the combination table in the Databook
  2. Perform a check of the power supply, connections, wiring between the outdoor unit, indoor unit and (separate) domestic hot water tank (if applicable)
  3. Perform a check of the main PCB

The full answer, free

  • 7 more checks in order
  • How to put it right, step by step
  • The manual page for this fault (page 64), right under the answer
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Safety: Isolate the outdoor unit and any backup heater, and give the inverter capacitors time to discharge before you open the electrics. Anything on the refrigerant circuit needs F-gas certification.

From the Daikin manual for the Altherma. Check the model on the data plate before you order parts.

Other Daikin Altherma fault codes