bad smell from floor vents

I've got a 2016 3rd gen, have had it since March 2016 and have roughly 8k miles on the vehicle. As of about a week ago I've noticed an intermittent, foul smell coming from my truck. If I had to pinpoint the smell, its somewhere between a urine drenched diaper and a decaying animal. It comes in waves and it isn't always present, I've tried to play around with my settings to see if I could pinpoint it. I'm in Maine so I haven't used the A/C for months. The only vent that seems to have the odor is the floor vents specifically (defroster vents and front facing vents don't produce the odor). Recycling the cabin air seems to eliminate the smell, and there doesn't seem to be any difference if the A/C is on or off.

Any suggestions for trouble shooting? Obviously my hunch is maybe a mouse got into the duct work somewhere, though it feels a little far fetched. Given that its only from the floor ducts I'm ruling out something in the cabin filter (otherwise that would affect every vent). I could have the dealer look, but I don't mind doing some digging around and I definitely don't want to pay for them to do something I might be able to solve on my own.

Thanks in advance

 

Probably a rats nest

 

By chance have you checked if you had any dead rodents in your engine bay?

 

Is it just after taking off your boots from a long day of hard work?

 

I vote rodents too. Check your cabin filter. Had mice make a nest in my WRX about 10 years ago. Didn't realize right away. Foul smell. Then one day I heard something hit the fan. I knew something was off. Pulled the cabin filter to find a nest. Yanked a fair portion of the duct work and fan out of the car. There were several desiccated rodents in there. Washed the whole works with bleach and sprayed lysol throughout the ducting that I couldn't remove.

 

Supporting the rodent theory is that I don't have a garage and have to park outside. Of course, this has also kept me from digging through my engine bay as its basically dark when I leave and get back from work. I'll try and poke around during my lunch break, might have to wait until the weekend. Thanks for the quick suggestions.

 

Alright problem solved. Just me being an idiot and not checking the obvious first, there is something foul smeared onto my weathertech floor mats, thus the smell from the floor vents. I did clean out my cabin air filter anyway and there was a substantial amount of debris in there anyway, so I'm glad I checked that (very easy, took less than 5 minutes)

 

Oops! Somebody stepped in dog crap!