I have successfully gotten Yosemite installed on my E7240. It seems all is working, but WIFI. I have the Dell 1510 card installed, and it works in another laptop. I cannot "Turn On" WIFI. I'm guessing this might be an issue with the Wifi Switch, rather than the WIFI card itself. I can get this laptop to work just fine with Mavericks, but WIFI will not work with Yosemite. Thoughts?
BTW - Forgive me, I'm a noob. I don't know a lot about what I'm doing, but I've gotten this far, and if I can get WIFI working, I'll have one hell of a Macbook Air. Please help if you can.