I'm having some trouble with my AC unit. It works very well, when it works.

When I'm on a rough road or hit a rather sharp bump the compressor drops out and may not work again until I hit some more rough road. If it is working and I'm on smooth roadways it will work indefinitely.

I suspect a ground issue. I replaced the compressor relay with a new one but I'm not sure the old one was really bad. But after constant use since 87 it was probably more than due. Likewise for taking the ground point loose, cleaning it of rust or corrosion and reconnecting it.

I just don't know where to look for the main grounding point on the system.

Anyone who knows anything who can help ?

When the unit is working, I can turn on the AC with the fan switch or with the fan running turn the unit on and off with the AC button beside the fan switch. I've eliminated the switch. This is why I suspect the grounding point.