Chosen Solution
Is the fan controller located on the logic board? Trying to fix my always on fan. Already tried all resets, firmware solutions. Thanks -
@patricknholman I bet it’s a single component along the fan connector that has failed because of liquid damage. I’d be checking the voltage and resistance of R5660 and R5661 as well. You have to start working from the fan connector backwards to see what has failed. It will help if you post some images of your logicboard so we can see what you see. Use this guide Adding images to an existing question for that. Of course, like @mayer already said a fan controller software program should work as well as a work around.
My bets are on either the trackpad cable or I/O cable (runs on top of fan) being damaged by the liquid. Check the pins on both sides of each of these cables, if they have corrosion or are black, replace them. Check the insides of the I/O ports too for burnt pins. If either of these are bad, the fans will start to ramp up during boot, and stay high. Sometimes the keyboard itself can cause this problem, or the trackpad; but it is most likely one of the above.
It’s in the fan. Replace it. Here’s how: MacBook Air 11" Mid 2011 Fan Replacement
