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Daikin Altherma fault A1-00

Zero cross detection problem

Heat pump

What it means

Power supply abnormality. The sinus of the power supply crosses the 0-axis too often in ±10 seconds.

Likely causes

  1. Faulty main PCB
  2. Faulty inverter PCB
  3. Faulty or disturbance of the power supply (power supply MUST be within range of nominal operating voltage ±4%)
  4. Power drop
  5. Short circuit

Where to start

  1. Perform a check of the main PCB
  2. Perform a check of the inverter PCB
  3. Check if the power supply is compliant with the regulations per section 4.1 Electrical circuit

The full answer, free

  • The readings and component tests from the manual
  • How to put it right, step by step
  • The manual page for this fault (page 28), 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