A search on this forum came up with nothing, so I figured it might help someone else in the future if I posted my story here.

About a week ago (and ever since), upon starting my RX8 I was hit by a very strong apparent animal pee smell coming from the HVAC vents. The smell was so strong that I had to turn off the blower fan and open the windows to drive the car at all. An internet search revealed one thread on another forum where an RX8 owner reported a similar situation, but different smell, more like rotten fish or a dead animal. In that thread a couple different people responded that had similar experiences and each eventually found that a wild animal had apparently crawled into an HVAC inlet duct and died. Not sure where exactly an animal can crawl in, but no doubt there's an opening somewhere that's large enough for at least a small rodent to enter. So I figured maybe the same had happened in my case, except the animal peed rather than dying. So last night I removed the glovebox and pulled the cabin air filters to check for any evidence there, and voila!, one of the cabin air filters had a dark stain, obviously from a dried liquid, and reeked horribly of "the smell." Easy fix, just replace the filters, right? Not exactly. Unfortunately, visual inspection of the internal area of the blower fan housing just below the filter location showed evidence of the same liquid - it had soaked through the filter and dripped below. Of course, it dripped into the farthest corner of the housing, which my hands couldn't reach via the narrow opening designed for changing the filters. So I enlisted my 12 year old daughter to handle this part of the process - of course, not telling her exactly what she was wiping up but insisting she wash her hands thoroughly afterwards. She was able to get to at least 90% of it but couldn't quite get into the corners enough to get it all, and the smell persisted, although not nearly as strong, when re-starting the blower fan. So I ended up removing the fan from below, which is surprisingly easy - just 3 screws and a quick disconnect wiring harness, and was able to reach through the resulting hole from below and get at those remaining areas with cotton swabs.

It surprises me that Mazda designed the RX-8's HVAC air inlet(s) without some type of coarse mesh, etc., blocking the passage in order to prevent this type of thing from happening.

I hope this information helps someone, some day.

 

Selecting "ReCirc" on the air lever (opposite of the outside air symbol), closes off most of the HVAC ducting to animal access. It shuts the door labeled '7' on the attached drawing.

 

That door (#7) is located immediately above the cabin air filters, so shutting it (via recirc button on dashboard) would stop invaders just short of where my nemesis got to. But to be honest, that's probably a worse situation than an animal passing through that flapper door and residing just below it on the filters, as the filters are easy to replace, and cleaning the area around/below the filters (if pee soaks through the filters) is very do'able, while the flapper door is covered in absorbent foam, would be a comfortable spot (when closed/"recirc") for an animal to set up camp and pee on, and appears to be very difficult to remove if had to be cleaned or swapped due to animal pee.

 

Thank you for posting this... I think the exact same thing has happened to me. I am going to check the cabin filter tonight. Really hoping I don't find a dead rat or kitten in there

 

Whelp, it wasn't the cabin air filter... my search continues

 

Happened to me to!! This solved it, thank you!!

 

Also, if you remove the source of the nasty smell, could be a good idea to do a general odor service too. Something along these lines.

https://www.napaonline.com/en/p/NCBA...&gclsrc=aw.ds&