I just purchased a 2012 MacBook Air with a broken screen. I'm using it as a desktop via an external monitor. I plan to do a factory reset and then upgrade to mavericks.

Will I be able to complete the factory reset and upgrade using only an external monitor?

Could I essentially accomplish the same result of erasing the previous owner's data and restoring the MacBook by just updating to Mavericks? Again, using only an external monitor.

1 Answer 1


Yes, it is possible, as long as the machine is run in clamshell mode.

Turn the computer on, plug in the external display, make sure an external keyboard and mouse is connected (wired or Bluetooth), then close the internal display. The Mac will enter clamshell mode and will use the external display as the primary display.

The only caveat with this is that the laptop screen must stay closed and AC power must be connected.

You can read more about clamshell mode in Apple KB article HT3131:

  • Thank you, for taking the time to respond. I'm now operating in clamshell mode. Will the MacBook maintain external monitor function during the OS reinstall? I concerned about losing external function and becoming unable to complete the install.
    – mike
    Nov 12, 2013 at 17:59
  • @mike Yes, it should. Clamshell mode should maintain through restarts, like it does when booted into an actual installation of OS X - if you restart normally when in clamshell mode, then it will still be in clamshell mode and the external monitor will show the Apple logo & boot spinner just like the internal display would.
    – grg
    Nov 12, 2013 at 18:09
  • How/where to I indicate that you answered my question(s)?
    – mike
    Nov 12, 2013 at 18:25

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