MacBook Air Won’t Sleep? Fix it with an SMC Reset

Dec 7, 2011 - 4 Comments

MacBook Air 11.6"

I’ve gotten in the habit of immediately putting my MacBook Air to sleep by shutting the lid, by far the easiest method if you’re on the go. Typically this works without a hitch, but today the Air didn’t sleep when shut. Because the MacBook Air has no moving hard drive or sleep light, I didn’t notice this until I went to use it again about two hours later when I found the machine to be unusually hot to the touch because it never slept as intended. From there on it became a repeatable occurrence, and while I’m not sure of the cause, the solution was just a matter of resetting the SMC:

  • Shut down the MacBook Air
  • Connect the MagSafe adapter
  • Hold down Shift+Control+Option+Power at the same time
  • Release all keys at the same time, then hit the power button again to turn the MacBook Air on

The key sequences for an SMC reset are highlighted below, this is specific to the MacBook Air but would also work on the newer MacBook Pro models:

Reset SMC on a MacBook Air

You’ll know the SMC has reset because the MagSafe light flicks on and off, and once you boot up, your MacBook Air should sleep normally again.

Ironically, I had the opposite problem earlier in the year where the MacBook Air wouldn’t wake from sleep.

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Posted by: AJ in Troubleshooting

4 Comments

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  1. Jim says:

    You can also try to delete the preferences for Energy Saver, they will be reset by SMC anyway.

  2. JohnC says:

    I’ve also had this with my Macbook Pro.

  3. Dave says:

    There’s another issue which could be at play, voice commands.

    I’ve found on both my macs that if I -use- a voice command, either by voice keyword or keyboard activation, the computer will no longer fall asleep. I developed an automator script to restart ‘speakable items’ which seems to work around the issue.

    If you’re using voice commands on (at least) 1.6.x and later OSX this issue can occur.

    Apple confirmed it as a bug, and promised to “consider fixing it” in an as yet determined later release. As of 10.7.2, the bug is still present.
    Dave

  4. Hans says:

    This has also happened with my Macbook Pro. Unfortunately it was in my bag for about an hour, and was literally skin burning to the touch when I took it out, which is really bad news for the hardware. I’m not sure if this is entirely the reason, but this hasn’t happened to me until the latest Lion software update.

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