My father-in-law was having outpatient surgery in North Carolina so I drove my ever-loving wife, “Robin” (not her real name), up there the day before so we could take him to the hospital. The weather forecast said there would be a big snowstorm the day of the procedure. Sometimes the meteorologists are right and sometimes they are way off. This time they nailed it. About 12″ of snow fell overnight and into the next day.
A few days after we returned to South Carolina and warmer weather we noticed an unusual sour odor in the car. Each day it got a little worse. I did some research and concluded the cause must be mold in the A/C vents as a result of the heavy snow getting in there and then melting. Mold likes cool, moist places to grow. The car probably has a design flaw with a low spot in the ductwork trapping the water and encouraging the mold to grow.
Numerous articles and You Tube videos said the solution is to spray Lysol, lots of Lysol, into the “cabin air intake” while running the A/C on high and the fan turned up all the way. My first question was, “What’s a cabin air intake?”
The car A/C has a button on the dashboard for switching between recirculate and outside air. When you push the button for outside air a flap opens and air comes in through that grill-type thing under the windshield wipers. The grill is actually a lot bigger than the hole where the air comes into the cabin ductwork and when I tried to spray the Lysol into it, most of went on the grill and not much went in the vent hole itself. Clearly the grill had to come off.
The key to removing the plastic grill covering the cabin air intake is to first remove the windshield wipers and then pop it off. (Click through the photo slider.) Then you can mainline the Lysol right into the duct while the A/C is on full blast.
That made the car smell better–at least more Lysol-y–but after a few more days went by it was clear I had to try something else.
There is a cabin air filter that can get dirty and even moldy so I decided to swap it out with a new one, which costs less than $10. To get to the filter, and this was a surprise to me, you take out the glove compartment. What could be more obvious? It actually isn’t all that difficult and you don’t need any tools. (See the photo slider.)
The first step is to empty the glove compartment. Trust me, you want to do this. I’m not saying how I know. Then pull off the little arm on the right side and turn the dial on the inside on the left. (My car is a Hyundai Sonata so the procedure for yours may be a little different.) Pinch the tab on the filter cover and pull it off. Then slide out the filter.
While I had the filter out I sprayed more Lysol in there while the fan was running. New filter in. Cover on. Glove compartment re-installed. And … same results. Better for awhile, especially if you like the smell of Lysol. But clearly not the final solution.
I put an electronic house air purifier in the car and ran it all night long. A little better but no dice.
Robin wouldn’t even ride in the car so she put up no resistance when I said I was going to take it to the dealer and complain about the lousy ductwork.
The mechanic took one whiff and said it was a dead animal. Now I don’t even carry live animals in the car let alone dead ones so I was, shall we say, skeptical?
He said an animal will usually crawl up into the air vents and get in the ductwork and at some point, ahem, expire. So he took off the dashboard and opened up all of the ducts. Nothing. Then he took out the driver’s seat. (Please finish swallowing your drink before reading the next sentence.) Under the seat was a dead rat! How disgusting is that???
My ever-loving wife’s reaction was, shall we say, “spirited.” It took her about 10 nanoseconds to realize that a dead rat was once a live rat that could have made its presence known at an inopportune time and/or place. (One could ask when an opportune time for an appearance would be. Fair question.) Robin immediately dubbed the car the Ratmobile. It is no longer the Hyundai or the Sonata or even my car. It is the Ratmobile.
Unfortunately, removing the remains of the deceased doesn’t get rid of the smell, which gets into the seat and wall fabric and carpet and anyplace porous.
I vacuumed and scrubbed and sprayed everything inside the Ratmobile. Many times. I used cat litter and baking soda and vinegar. (Note to self: do not mix the baking soda and vinegar together because it makes a salt that sticks to the carpet like glue and was next to impossible to get off even with a steel wire brush.) I ran the air purifier inside the Ratmobile for two days.

We noticed that the strongest smell was when we would first open the door. I decided the odor must be in the rubber foam door gaskets because they are porous and air gets sucked in and out of them. So I sprayed more Lysol on the gaskets all the way around the open doors. This seems to help along with the ever-present mounds of baking soda on the carpet.
After 8 months of treatment the smell is almost gone even though Robin curls up her nose every time in anticipation before she opens the door. A conditioned response no doubt.
Completely unrelated to this article, I have a good used car for sale if you are interested.