No DC power, so we have no heat or air conditioning

OP here

Thanks for all our your help.

We got some excellent info on a Monaco owners forum as well and it seemed that our problem was the battery cut-off solenoid, or salesmans switch.

We were told how to bypass it, but were uncomfortable doing it ourselves.

Fortunately our mobile rv mechanic was able to come out. It took him 15 seconds to by pass it and all is well. We have DC power again. :)