TradeAssistIQHome

Daikin Altherma fault U2-00

Outdoor unit: defect of power supply voltage

Heat pump

What it means

Power supply abnormality or instant power failure detected; unit will stop operating.

Likely causes

  1. Faulty or disturbance of the power supply (power supply MUST be within range of nominal operating voltage ±4%)
  2. Power drop
  3. Short circuit
  4. Faulty compressor or miswiring of the compressor power supply cable
  5. Faulty outdoor unit fan motor
  6. Faulty main PCB
  7. Faulty inverter PCB
  8. Momentary drop of voltage
  9. Momentary power failure
  10. Damaged or broken wires between power supply terminal and hydro PCB
  11. Incorrectly connected wires
  12. Residual voltage in main circuit capacitors after power off

Where to start

  1. Check if the power supply is compliant with the regulations per section 4.1 Electrical circuit
  2. Perform a check of the compressor
  3. Perform a check of the outdoor unit fan motor

The full answer, free

  • 29 more checks in order
  • The readings and component tests from the manual
  • How to put it right, step by step
  • The manual page for this fault (page 58), right under the answer
Ask about U2-00 freeCreate a free account

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