MacBook Air: Resetting the SMC
Imagine coming home one evening, plugging your MacBook into the MagSafe power adapter and go to power it on… but nothing happens. Your beloved Mac seems to be responding to the power adapter, because it lights up green initially and then orange, but you cannot get it to respond. You try starting your Mac using safe mode, but nothing happens no matter how long you hold down the power key. You cannot get it to wake up and no matter what key you hold down, the screen remains completely black. What can you do to fix your beloved computer?
If you experience all of the above, you may need to reset your computer’s System Management Controller (SMC). In some cases, resetting the SMC may be the only method to resolve the issue; however, Apple strongly advises that an SMC reset should only be attempted after all other standard troubleshooting has been performed!
Remember that the System Management Controller (SMC) is responsible for many low-level functions on Intel-based Macs. These functions include responding to presses of the power button; responding to the display lid opening and closing on portable Macs; battery management; thermal management; the Sudden Motion Sensor (SMS); ambient light sensing; keyboard backlighting; Status Indicator Light (SIL) management; battery status indicator lights; selecting an external (instead of internal) video source for some iMac displays.
Typically to restart, you would simply remove the battery, thus rebooting the computer; however, the 2009 MacBook Pro and later, all models of MacBook Air, and the late 2009 versions of the MacBook actually prevent you from removing the battery on your own. Fortunately, it’s still easy to reset the SMC on these versions by following these easy steps:
- Shut down the computer.
- Plug in the MagSafe power adapter to a power source and connect it to the Mac.
- On the built-in keyboard of your Mac, press the (left side) Shift-Control-Option keys as well as 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 the device on.
Resetting the SMC does not change, the contents of PRAM, which is also known as NVRAM on Intel-based Macs.
The LED on the MagSafe power adapter may change states or temporarily turn off when you reset the SMC. This is normal and no cause for alarm. .