Wi-Fi hardware not installed I've a late 2008 MBP. It's worked fine up until Monday when the wifi stopped working. It now says "Wi-Fi: No Hardware installed". I've tried looking for it in the system prefs and it's gone. 

I've tried reinstalling Yosemite, I've tried resetting pram and smc. No joy. I've repaired disks and permissions.

My bluetooth works as I can stream music to the hifi. The built in camera works too as I can skype, other research has suggested that if these work, it's not a hardware fault. 

I've ran a AHT, which came back as no errors. Would it still report error if the airport card/connection doesn't exist?

Has anyone any suggestions before I open her up and poke around?
Sounds like it might be a bad Airport card, if you have the tools, open it up and then disconnect and reconnect the antennas connecting to the card. If that doesn't work, remove the card, clean the contacts on the card and then reinstall it. If that doesn't work, you'll need to buy a new card, specific for your model of MacBook Air.