TradeAssistIQHome

Vaillant aroTHERM fault F.1117

Compressor: phase failure

Heat pump

What it means

A phase failure has been detected at the compressor, potentially caused by electrical supply, fuse, or connection issues.

Likely causes

  1. Defective fuse
  2. Incorrect electrical connections
  3. Mains voltage too low
  4. Compressor/low tariff power supply not connected
  5. Energy supply company lockout for longer than three hours
  6. Low ambient/outdoor temperature causing heating flow temperature to drop
  7. Low outdoor ambient temperature
  8. Low heating flow temperature at outdoor unit
  9. Heating flow temperature of outdoor unit below 4°C
  10. Heating flow temperature below 4 °C
  11. Negative outdoor temperatures Heat pump fault Power cut Defective compressor

Where to start

  1. Check the fuse
  2. Check the electrical connections
  3. Check the voltage at the heat pump electrical connection

The full answer, free

  • 27 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 37), right under the answer
Ask about F.1117 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 Vaillant manual for the aroTHERM. Check the model on the data plate before you order parts.

Other Vaillant aroTHERM fault codes