All 3 error codes means there is something wrong with the sensors - the difference between the error codes are which type of sensor is coursing the problem.
F6 means outdoor ambient air sensor fault
F7 means outdoor coil sensor fault
F9 means outdoor compressor sensor fault
note: all 3 sensors are connected via the same plug so if one sensor is faulty then all the sensors need to be replaced. A multi-meter can be used to check for resistance, no resistance means faulty sensors.
Check to see if the connection between the sensors and the PCB is firmly connected. Then check the sensor sockets are clean - as these are exposed to condensate water so they can corrode - use a small abrasive brush to clean the sockets.
If the sensors are connected properly and the sockets are clean then the sensor set needs to be replaced.
To order a new sensor you can contact us via email at email@example.com or call us at 0370 3344 556.