[jsb5717]

Welcome aboard! Sorry for your furnace issues...but you're not alone. Furnace problems are pretty common.

The fact the furnace is igniting eliminates a few troubleshooting steps. We know it's not a sail switch or igniter.

First thing to check is whether or not you have an auto-reset fuse (black). I doubt it's that at this point since the fan keeps running. But if you do, I'd still replace it with a standard 15A fuse (blue).

With your symptoms the usual suspects are:

• Air flow, as Zack said. Check to make sure that there's no bug nest impeding flow.
• Hi Limit Switch - If it's tripping prematurely then it will kill the burn. They rarely go bad but are pretty easy to bypass with a jump wire to test.
• Burner/Diffuser - This is located on the burner assembly, mounted to the propane valve. It requires that you disconnect the propane line from the furnace and pull out that assembly. The burner (or diffuser) is very simple. All it does is evenly disperse propane for a clean burn. If it is rusted over so that holes are plugged, or burned through with larger holes, then your symptoms is the result. Once it's out it's very easy to replace if needed.
• Propane Regulator. The furnace has a high demand for propane flow. An RV regulator is preset at 11" column inches of flow. The furnace needs all of that to properly run. If regulator output diminishes your other appliances can still run normally, but the furnace can falter. The first time our furnace failed it turned out to be the regulator. If your rig came with a Fairview regulator then that could easily be the culprit. If you need to replace it get a Marshall Excelsior.
• Propane valve (in the burner assembly). Not as likely but they can fail. I ended up replacing one on my buddy's furnace. Don't start with this one.
• Main Control Board - Not as likely but always a possibility. Since it controls all functions there are several ways they can fail

Troubleshooting these things can be tricky without all of the proper equipment. That often results in starting to just replace parts...which is a bummer but may be unavoidable. Do the easy things first that don't cost anything. I now have a backup part for every replaceable component on our furnace. After having it fail 3 times I just decided to have the parts handy so I don't get stuck in the cold away from home.

Good luck with the project and please keep us up to date on progress to see if there's more insight to get you up and running.