I have a 2011 Edge Limited AWD with 7k miles and the same problem, A smell of hair burning under hard acceleration condition and the A/C in recirc mode, The Dealer couldn“t find anything wrong, (they have searched for signals of burned oil in transmission, ptu, engine, oil leaks, etc...) but they smelled it in a test. It seems to have some correlation with the transmission, not the engine. let me know if you find the solution, please.