I bought my Renegade Trailhawk in the fall so I didn't need the AC but I noticed it didn't really feel any different when on. I figured I'd just have the dealer look at it when it was due for its first oil change. As the miles got higher, I noticed that after longer drives I heard a squeaking like a belt or pulley coming from the engine, it was very noticeable after a long 200 mile drive so mentioned it and the AC issue when I turned it in. They kept the car for a day and a half and their best guess was that the issues were related because the AC had no refrigerant at all. I still have to do a long drive to confirm everything is good but the AC definitely works now!