We have a 03 3500 2 wheel 6 speed dually and the dang thing just started acting up the other day engine started missing really bad took it to the shop and they could not find a thing wrong with it,so we started jacking with it and un pluged the clutch fan and it runs great now but the A/C dont work. If I plug it back in the truck runs like POO and the a/c works. I have never heard of this before. . How bout yourself. . Thanks 573 426 5199