Chosen Solution
My fan had suddenly stopped working (I think), and it showed 0 RPM in all diagnostic apps, but fan diagnostics say that the fan is working normally. Still, I replaced the fan with one I bought on eBay, used but apparently tested. Nothing happened. It still shows 0 RPM and the fan isn’t rotating. Temperatures go high and it slows down (Mac) or shuts down (Windows). So, do you know if it could be any software problem, or logic board problem, any way to test it? This is really annoying as I can’t use it for multitasking at all. PS: Resetting SMC didn’t help. Thanks.
See if you can over-ride the fan using TG Pro. Are you able to do that? Do you hear it running at full blast? If not you’ll need to decide if you want to fix the system your self or allow Apple to do it for you. I would try Apple first as the newer ‘Thin series’ iMacs are much harder to open than the older generation. Many people have damaged the display assembly just in the process of opening the system which can be an expensive mistake. Apple might even do it for free under warranty at their Apple Store!
