I'm having problems after updating my MacBook Air:

  • the fan noise is very loud
  • the computer is very slow
  • the battery flattens quickly

I've tried the following:

  1. Restoring the OS
  2. Downgrading the OS
  3. Resetting the PRAM

I also trIed resetting the SMC but I can't do it! When I press the left shift-control-option-power buttons the computer starts up immediately, so I am sure the SMC is not reset.

On the Activity Monitor the kernel_task is over 350% CPU all the time!!

  • The Boot ROM version is: MBA61.0099.B22
  • SMC version (system): 2.13f15
  • i7 processor
  • SSD

I don't know what to do - help please.

2 Answers 2


It doesn't seem you're resetting the SMC correctly. Here’s what you do for a MacBook Air:

  1. Shut down your computer
  2. Keep the power cable plugged in.
  3. Press at the same time shiftoptioncontrol (on the left side of the keyboard) and the power button
  4. Let go
  5. Turn your computer back on with the power button.

Let us know how you go. Many of your symptoms are listed in Apple's article on when you might want to try a SMC reset after performing a somewhat long set of other checks first to be sure it's not software or basic settings:


Your 3 points are all strongly related. Hold the Power button and keep holding until the mac shuts off. Then release the Power button. Wait ten seconds. Then do the SMC reset, doing it 2 or 3 times does not hurt.

  • 1
    It doesn't help either.
    – Tetsujin
    Commented Dec 11, 2016 at 16:10

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