I have a 2011 GMC Acadia SLT. The defrost had stopped working last fall, so I took it to a local mechanic. The actuator door had an issue. Anyway, I dropped it off to him in the morning, and picked it back up late afternoon. When I picked it back up, the A/C no longer works (light just blinks 3 times), but the defrost does now. I had not had any A/C problems prior to this, but the mechanic insists that he didn't do anything that would have messed with the A/C. The guy wanted to charge me extra $$ to look at the A/C, saying I had no "proof" that it worked before I took it in. Anyway, I decided to wait it out through the winter and get it looked at in the summer. I've been trying different places, but everyone wants to charge me $200+ just to look at it and diagnose it. I'm thinking it's probably something simple like a fuse or switch or something. Any ideas?