Chosen Solution
So my wife’s 2015 MacBook Air fell of the couch and cracked the display. It was still usable, just had an annoying crack running down the side. I finally replaced the display and upon startup the fan goes to high speed and I get kernel task when i put the CPU under any type of load. All that I changed was the display, not sure what to do.
Try unplugging the camera cable as this can cause problems relating to temperature sensors that are connected to the SMC (System Management Chip) which can cause the high speed and throttling problem. Check step 17 of this guide: MacBook Air 13" Mid 2013 Display Assembly Replacement You don’t need to remove all the boards but simply have that cable unplugged temporarily to see if that fixes the problem. If it does I’m sorry to say but the screen assembly may be faulty if this is the case (bad webcam).
