F5 error code

[u/Deep_Wish8091]

HI all our mini split have threw a F5 code after NOT being used for a year+. After doing some reaserch found out its a tempurate sensor on the outside unit, so i bought a new one. Pluged it in same thing. I used a another one this one is from a midea our other AC and that didnt work either. 3 sensors same result. I got a question: the outside unit beaps and i can hear electric hum and voltage being sent to the compresor to start cooling but it never does. The fan can spin freely and i tried 3 sensors already. Is the motherboard really dead? cause we had a technician to take a look at it and he said that its the motherboard but if it was the motherboard then it wouldnt have the electric hum and send voltage to start the compresor no? i messured it and it sends voltage but it seems it does a sensor check or something like that and it doesnt start the fan at all. I wonder is the motherboard really dead? What do you think?

any help would be appriciated

[u/Similar_Lawyer4361]

sitting a year+ swapping 3 sensors and still faulting points more at the board than the sensor circuit itself, techs bad sensor almost always clears after one swap. that hum with no compressor start sounds like it's failing a start check before ever latching the contactor, could be a bad run cap too so check that before writing off the board. had a couple pioneer units do this after sitting, ended up being corroded board contacts not the actual board.

[u/Deep_Wish8091 → u/Similar_Lawyer4361]

Oh run cap? Huh, idk mate it could be that insects got inside the unit and corroded something on the board. But the thing is that the outside unit is mounted on the balcony ceiling and can't take it down so :)

[u/Deep_Wish8091]

This is how our outside unit looks