About a month ago my A/C started blowing hot air, I bought one of those A/C recharge kits from autozone and it only lasted a few weeks before blowing hot air again, so there is an obvious leak somewhere. I took it to a local mechanic but they wanted to charge 110$ just to look at it and tell me what's wrong. Whenever I turn the vehicle on and the A/C starts up there is a subtle hissing sound coming from inside the dash, it sounds like a loose air hose or something. When I turn the A/C fan speed up the hissing sound gets louder. Any help would be much appreciated.