I had a bag of dry dog food in the garage and a mouse or rat took an awful lot of it into the vent system, to store it I suppose. The smell is bad. I have removed/replaced the cabin filter twice. I have tried a plug in ozone device. I vacuumed as much as possible out of the vent through the cabin filter opening behind the glove box, don't know if I got it all. Honda dealership tried some kind of ozone machine and ran it for hours to no avail. Help.
Until you get all of the dog food and rodent feces out of the duct work, you can do all you want to the car and you'll not be rid of the smell. You'll more than likely need to completely dismantle the HVAC system and remove everything which is left behind (or pay someone to do it for you). There's just no easy way to make this happen. An ozone generator is a great thing for removing smells, but as long as there's something there to generate more things to smell, it will just keep coming back.