Chosen Solution

For a couple weeks the Macbook Air has been shutting down suddenly. It might work fine for a few hours, then the display goes black and it’s shut down. To restart it, I have to wait a few minutes, or unplug the Magsafe and then plug it back into the computer, at which point it starts up. After the first shutdown like this, the second usually comes faster, e.g. after 15-20 minutes. What I have done:

  1. reset the SMC and PRAM.
  2. used the Air with the battery unplugged; it seemed to fix the problem, so I bought a new battery, which works fine, but the sudden shutdown problem has reappeared.
  3. replaced the I/O Board cable.
  4. removed the internal SSD and started the Air from an external disk. The problem persists, though. At this point, what do you think? I/O Board? Thermal paste on the processor/heatsink? (The Air doesn’t get really hot.) Or the logic board itself? At this point I’d like to try to fix it without replacing much, due to cost. I’ve seen in the guides that replacing the thermal paste is a fairly long procedure, but if you think it might be the problem I would try that first. Many thanks. Update (03/07/2020) Ok. Here are pics from Coconut Battery and TG Pro. Thanks for any help.

Problem solved! I disassembled the Macbook Air and removed the logic board, but after close inspection there didn’t seem to be any corrosion or liquid damage. I removed the heatsink and found that the original thermal paste had dried up and it came away in little chunks. There was probably little cooling at all. After cleaning heatskink and processor, and applying fresh thermal paste, the Air booted up next time and seems to be working fine. Temperatures are normal even under heavy workloads, and I haven’t had any sudden shutdowns since. It’s been a couple days now and it looks to be working well again. Seems like a logical fix now, but I hadn’t thought of it earlier. Would recommend it as one of the first things to look for on older laptops. Thanks for your help.

It looks like your systems fan has failed! Note the fans speed is 1998 RPM which is the off condition. At this point I would try running the onboard diagnostics to see if we get any errors. Restart the system and press the D key alone. You may want to chill the system before you run the test. I would also open the system up and blow out and dust buildup within the fan using a small soft paint brush and a very short blast of can’ed air, too hard a blast of air can also damage it! Here’s the needed part: MacBook Air 13" (Late 2010-2017) Fan And here’s the guide you’ll need to follow: MacBook Air 13" Mid 2011 Fan Replacement