Dead mouse or something: How to find?

Bill001 wrote:
Well this brand new RV has something dead in it. Subtle order in the unit if closed up, but comes out of the vents if I turn on the furnance.

I'lve looked into the access panels I have access to. No luck. The return louver to furnace, doesn't show much. Need to get a small mirror to look up this vents.

Any suggestions on finding this thing?

Then you've got a dead mouse in the heating duct work and the only solution is to replace the affected duct work. I speak from experience, having had the same issue myself a few years ago with our KZ Spree. The first time I test started the furnace in the spring the smell was overwhelming :E ... found nests in 2 of the 5 ducts, tried to clean up the mess to no avail, and was only able to fully solve the problem by installing new duct work. I was lucky as the duct work was flexible tubing running above floor through cabinets but if yours is underfloor with an enclosed underbelly you're in for a LOT of work. Has to be done though as pulling each section of duct work for inspection and replacing it is the only way you'll fully resolve the problem.