I haven't hooked it up to 50 amps as the coach was designed for, but the furnace did not come up when I hooked it up to my house line either. When I bought it, the dealer had it connected to 50 amps and it worked. The frustrating part is that it quit on me halfway home going through Wyoming at night when it was 0 degress out.
Right now, I don't get anything from the furnace. I replaced all 4 batteries today, and while that fixed some things, was not sufficient for the heat. I'm taking it in Monday and will report if you like what they find.