Vaillant aroTHERM fault F.819

Freq. converter fault: overheating

Heat pump

What it means

Internal overheating of the frequency converter has been detected.

Likely causes

  1. Internal overheating of the frequency converter
  2. Maximum environmental temperature of the outdoor unit (46 °C) has been exceeded

Where to start

  1. Check the frequency converter's air route
  2. Check that the fan is working correctly
  3. Allow the frequency converter to cool and restart the product

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 37), 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 Vaillant manual for the aroTHERM. Check the model on the data plate before you order parts.

Other Vaillant aroTHERM fault codes