Daikin Altherma fault EA-00

Outdoor unit: cool/heat switchover problem

Heat pump

What it means

Room thermistor is NOT functioning within operation range, indicating a problem switching between cool and heat modes.

Likely causes

  1. Faulty 4-way valve
  2. Faulty main PCB

Where to start

  1. Perform a check of the 4-way valve
  2. Perform a check of the main PCB

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 40), right under the answer

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.

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