I have a 99' Chrystler Concorde, I recently drove from NY to KS about 4 months ago. My A/C was on for about half the trip when I tried turning it off, and it turned full blast on defrost, and on my feet. I can turn the temperature up and down however, when I try turning pushing the off button, it goes full blast. I had this fixed by a garage as soon as I got to KS, and it worked fine for about 2 months, and now it's doing the same exact thing. Any suggestions would be greatly appreciated!