For many years I always left my climate control at 70 degrees, year round with no issues. Over this past summer it started blowing hot air when it should be cool air, I found I had to set it to 63 degrees and it would cool OK. Now with colder weather, set at 63 degrees it is blowing hot air even though I feel the cabin is already much warmer than that. If I go to the LO setting it does blow very cold (that was true in the summer), and I was able to be comfortable this past summer with the lower 63 degree setting. I am not sure if this problem is A/C charge, or something related to either the cabin temperature sensor or possibly the hot/cold air mixing malfunctioning. Also I sometimes hear a faint kind of chattering noise from under the dash, but it is not the fan. It stops if I switch the climate control to off. Has anyone had any experiences like this?