The April 2014 update of Apple's 13" MacBook Air features refreshed dual-core i5 and i7 processors, plus slightly increased battery performance.

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MLB issue? Fan spins up/down twice before booting.

I've noticed this trend with liquid damaged machine, and have it again with a machine in front of me. I'd like to know the root issue and how to properly fix it if possible.

After liquid contact, a logic board displays the following behavior:

  • Press power button.
  • Fan spins up and then down after a few seconds.
  • Fan does the same again.
  • Fan spins up, machine boots as usual and fan acts normally.

I've reset the SMC, checked that it happens in minimal configuration as well, and run all tests in the Apple Service Diagnostic (which this machine passes).

If I use it for a bit and then shut it down, and then boot again, oftentimes it will boot up without the above fan spin ups/spin downs. But if I leave it sit for awhile, it will do it again.

Does anyone have further insight?

Answered! View the answer I have this problem too

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Bumping this thread. I see this issue all the time with liquid damaged MBA boards and am no more enlightened about why it happens. @dan, @mayer , @oldturkey03 ?


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This is normal behaviour on 2013-2014 MacBook Air machines, it happens when booting with no battery connected or after the battery is reconnected.

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Pretty sure this is normal for some MacBook models. I've heard Louis rossmann reference this behavior a few times on his YouTube channel

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Colin will be eternally grateful.
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