Joule Modul Air fault 12

No communication with the room thermostat

Heat pump

What it means

The heat pump has lost communication with the room thermostat. This is a locking fault requiring installer intervention to override.

Likely causes

  1. Faulty electrical connection
  2. Thermostat malfunction

Where to start

  1. Check electrical connections
  2. Check the thermostat is operating correctly
  3. Trace tank sensor wiring (Top Sensor, Bottom Sensor) to P6 connector on Modul-AIR Main PCB Board

The full answer, free

  • 9 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 105), 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 Joule manual for the Modul Air. Check the model on the data plate before you order parts.

Other Joule Modul Air fault codes