Rv noob here! Hi everyone!

4theriders, welcome to the world of RVing. We've been RVing since 1976. I think you will like it, as we do. Have you checked the 12v fuses in your converter panel? In your '08 Thor Four Winds MH (motorhome), you probably have a WFCO (brand name) converter. The panel under the lid should have an LED lit if one of the fuses is blown, and the fuse positions should be labeled as to what circuit each one energizes, but I've had a fuse blow in a WFCO converter before and the LED did NOT come on, so it wouldn't hurt to pull the furnace fuse and check it manually, either visually or with a volt/ohmmeter. I suppose the seller informed you that the LP gas must be turned on in order for the furnace to heat. If not, the fan may come on when the thermostat calls for heat, and you may hear the electronic ignitor trying to light the burner, but the burner will not light, and the fan will time out after a few minutes and shut down. Even if the gas is on, if the LP system hasn't been used in a while, or a tank has been disconnected to be filled lately, the system may have air in it and the furnace may not light. Try lighting the stove burners and letting them burn for a minute or 2 to help purge air out of the lines, and try the furnace again. Hope this helps you.