Originally Posted by justintime
I do not have 120v to Ac the black wire going to unit is broken or disconected between the switch and the AC
Ok, I assume this "switch" is the circuit breaker in the main 120V panel? And you believe there is a junction box between that panel and the junction box that is located right at the A/C?
If this is correct, it would be highly unusual to have a secondary junction box as that breaker is dedicated to the A/C unit and nothing else. Of course with a 30+ year old coach, any PO could have changed many things. If you do have a secondary box, I wouldn't know where it would be. You may have to use a wire tracer to find it.
Since this is a second A/C unit and assuming you have a generator (where it's 20amp circuit is dedicated to the rear A/C), have you tried the rear A/C with the generator?