My transmission stays on third gear

My tuck (Classic hd) works perfect when I am driving without my AC on. As soon as I turn the AC it slips and stays on third gear. And it never fails to happen. Sometimes if I turn my truck off with the AC on my truck will not turn on unless I lift my junction fuse box. I recently replaced the blower resistor and it worked for a couple of days but now it does not even blow air.