Dead animal I n 2008 AC/can’t find it

If something got as far as your foot, then it’s in the ductwork after the blower.

 

Good Luck,

That's nearly a Stephen King like moment.
Bad enough but not uncommon that a rodent dies somewhere in a vehicle. But to have the smell then be driving along and have wet "corpse juice" dropping on your foot seems like foreshadowing.

Good Luck finding the remains.
This would be a full Haz-Mat suit up for me.

 

Before taking the duct work apart inside the car, go after easier stuff on the outside... Like black plastic vent cover that comes off after you remove windshield wipers. I found signs of nesting under that before. Also inspect under black plastic flaps around wheels and if you can put the car on a lift and do a thorough undercarriage inspection. Main thing is how it got inside the car... There's no use looking for it in places it can't get into, I'd say the ducts after the filter are not likely...

PS: I've often been misled to think an electrical burning problem was coming from the dash when it actually was coming from the HV battery pack.

 

Also check carpet and upholstery... Perhaps milk or other nasty got spilt last Spring... Any corpse that died inside the car is going to be small and won't stink for long...

 

Since you're still on the hunt, you might as well tear into the rear passenger area around the 12v battery and take a look there.

Once inside you can go a little deeper and clean up the HV battery fan (be sure to also check the power connector for corrosion), where you will also have much of the same attached to the fan vanes.