updated 07:42 pm EDT, Mon July 21, 2014
Fixes an issue that caused fans to ramp up, also cures wake-from-sleep issues
On Monday, Apple posted an EFI update specifically aimed at the mid-2011 model MacBook Airs that are running OS X 10.9.2 (Mavericks) or later. The update addresses two wake-from-sleep issues: one in which the computer would take longer than expected to wake from sleep, and the other (more rare) issue of cooling fans ramping up to full speed on waking from sleep. Owners must meet both conditions (mid-2011 MBA, and running Mavericks 10.9.2 or later) for the update to apply.
The 4.3MB file can, according to Apple, only be installed over EFI versions 0077.00, 0077.08, 0077.0E and 0077.0F. Users can check what firmware version they are running by going to the Apple menu, selecting "About This Mac," "More info" and "System Report." The new EFI firmware update version is 2.9, and can be downloaded through Software Update for the affected models or Apple's Support Downloads web page.
As a firmware update, Apple recommends that the unit be plugged in or have a minimum charge of 25 percent or more before attempting the firmware upgrade. Installing the package will cause a restart, with a status bar to indicate the progress of the update. "Your computer's fans will run at full speed during the update but will return to normal speed once the update completes," Apple notes in its default firmware update instructions. As with all such installs, the company says uses must not "disturb or shut off the power on your computer during this update."