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I bought a new MBA 11" i7, it's about two weeks old.

I've noticed that as soon as the fans come on, they Never turn off. If I watch a video, or do any slightly heavy lifting, the CPU hits 70C, the fans come on at +6000rpm and never turn off.

Even if the CPU load is less than 1% for an hour or more, the fans stay on full-blast and the CPU temp stays at ~67C and the case at ~35C. The room is normal temperature, it's sitting on a desk.

The only way I've found of making the fans turn off is to make the Mac sleep for a while.

Is this a known issue? Are other people having similar problems? What can I do to resolve this?

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Same here, MBA 13" i7. Resetting the SMC does not help, CPU load nearing 0%, CPU temp at 70C and fans: full throttle. very annoying. –  magma Sep 16 '12 at 23:25
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1 Answer

The fans are controlled by the System Management Controller (SMC).

The first thing to try when troubleshooting a fan issue is resetting that SMC. In fact, Apple says this:

After performing normal troubleshooting, these symptoms may indicate that an SMC reset may be necessary: [...] The computer's fans run at high speed although the computer is not experiencing heavy usage and is properly ventilated.

Apple has directions for all models, but I'll excerpt how to do it on your MacBook Air:

  • Shut down the computer.
  • Plug in the MagSafe power adapter to a power source, connecting it to the Mac if its not already connected.
  • On the built-in keyboard, press the (left side) Shift-Control-Option keys and the power button at the same time.
  • Release all the keys and the power button at the same time.
  • Press the power button to turn on the computer.

One other thing you can try is the app smcFanControl, which claims to allow you to exercise some degree of control over your computer's fans.

This is about all you can do as a consumer; if there is still a problem you will need to take your computer to an Apple Store.

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I'll give it a go. –  Ben Humphreys Oct 27 '11 at 1:46
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