Recurring electrical problem with AC/H and dash lights.

What is your question?

My local dealer service has been trying to fix this problem for over six months: AC/H does on and off. Either it will not turn on when I start the car and then (sometimes) it will come on when I hit a bump. Or, it will come on when I start the engine, and turn off when I hit a bump. I am only a university literature professor, but that seems like an electrical wiring short or loose connection to me. So far, the electric techs have changed fuses, changed out fuse boxes, changed controllers on blowers, and the problem is still there. Certain lights on the dash (i.e., oil/engine warning lights, A/C lights, etc.) come on erratically, but now the techs say they can't find or replicate the condition. What do I do now?!