With air conditioners, it is better not to do anything at all yourself. Instead, you change something in them and consider it no longer works. I am a computer repair specialist and in my experience, if not an experienced repairman fixed something, then where he repaired 100% there is some problem. Either we fixed the previous issue so that after a short time there will be new ones, or everything became much better than it was. Unfortunately, there are no universal methods of repair already, only an individual approach to each part and a unique tool for it.