I just upgraded my 2010 MacBook Air to Yosemite. It froze during installation, I shut it down and when I restarted it booted normally to Yosemite.

Now everything seems to be working ok, but I have no sound. My case is not like most cases where it defaults to an external device. I have nothing attached, no monitors, no external speakers.

When I check system preferences/sound, I get no output devices found.

Here's what I've tried: - rebooting - reset NVRAM - reinstalling yosemite (same freezing problem - waited for 4 hours) - remove plist files from Library/preferences/audio and restarting

Any suggestions?


  • Hey im having the same issue right now. no red light no input/output and even the usb access on the same side doesn't work! May I ask if you have solved this issue yet?
    – user119696
    Commented Mar 26, 2015 at 21:31

2 Answers 2


Reset the SMC:

1) Power down the system
2) Unplug all cables except Magsafe
3) Hold down left Shift + Control + Option + Power button for ~5 seconds
4) Boot machine up

This usually solves issues when certain hardware devices on the device itself aren't responding, especially when multiple do not work.


Reset the SMC and then check the headphone port for lint or materials.

If the SMC reset doesn't make a difference then restart the sound controller:

Open Activity Monitor locate 'coreaudiod' in the list of processes, select it and click on the X to quit that process. The process will restart straight away and in doing so may fix your problem.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .