Also check for mice nests. I had a mouse come stay with me for a while in an old car I used to have, and he made himself all at home inside my heater box. I think he used the blower fan as a squirrel cage wheel for his daily exercise! It was hard to get that crap out. I had to tear the whole dash apart, and clean out the heater box manually. And getting the urine smell out was a pain

in the butt. You better just hope it aint that on yours. This happened on an old '84 Cougar I had years ago.