Trailer fuse blowing?

I just bought a 2000 Prowler and am having problems with the furnace. It worked fine at my house, I took it camping the first time, and it blew a fuse. I replaced the fuse, turned it on and it immediately blew again. I put a slightly higher amp fuse in there, and it started tripping the trip on the blower. I tried bypassing the external trip and I saw the lights dim as if it were trying to start, but nothing out of the motor. After doing that I reset the trip, and the motor ran for about 1 second then tripped again. I dont know if this has anything to do with it or not (doubt it) but the only thing that has changed since I moved it from my house to the campsite was that we replaced the batteries. To verify that was not the problem, I disconnected the batteries and tried again off the power at my house. Suggestions?