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Daikin Altherma fault 89-01

Heat exchanger frozen

Heat pump

What it means

Warning 89-02 or 89-03 occurred 3 times, with less than 30 minutes between each warning. Unit will stop operating.

Likely causes

  1. Faulty refrigerant liquid thermistor
  2. Closed stop valve in the refrigerant circuit
  3. Refrigerant overcharge
  4. Clogged refrigerant circuit
  5. Non-condensables and/or humidity in the refrigerant circuit
  6. Water flow is too low
  7. Faulty refrigerant pressure sensor
  8. Poor water flow through high pressure side plate heat exchanger
  9. Incorrect refrigerant charge

Where to start

  1. Perform a check of the refrigerant liquid thermistor
  2. Check that all stop valves of the refrigerant circuit are open
  3. Check if the refrigerant circuit is correctly charged

The full answer, free

  • 9 more checks in order
  • How to put it right, step by step
  • The manual page for this fault (page 22), 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