Atwood 8500 Series 3 Problem

[GaryS1953]

I have a 1996 Coachmen Catalina 5th wheel with an Atwood 8500 Series 3 furnace. On our most recent trip when we woke up in the morning of our first day at the campground I noticed the Fridge error light was on. Doing a quick check I realized the 15 amp fuse was blown so I replaced it, and problem solved, and the fridge worked fine all day. The next morning the fuse was blown again. Doing some checking I found the fridge and furnace are on the same 15 amp circuit, and when the furnace comes on it is blowing the fuse. We didn't really need the furnace as it wasn't that cold, so I left it off and all was fine with the fridge the rest of our trip.

Now that I'm home I'm trying to fix the furnace in preparation for our winter trip. When I turn the thermostat all the way up to call for heat, there is the normal 15 to 20 second delay, then the fan comes on, but after about 3 seconds it goes off and the fuse is blown.

Any thoughts on what common problems might cause this?

Thanks!

[GaryS1953]

I've looked and don't see any obvious shorted wires. I've also checked the main power (red wires) going into and out of the circuit breaker, and I ha e 12.7 volts there. I've examined and removed the Time Delay Relay, and will take it to my RV dealer tomorrow to see if they can check it for me. And that's really as far as I've gotten so far.