When I turn on the AC it makes my Volvo smell like a litter box.

Dear Car Talk

Dear Car Talk | May 01, 1997

Dear Tom and Ray:

My car is a '93 Volvo 960. When I first turn on the air conditioner, it
gives off an odor which makes me think the car is harboring a well-used
cat-litter box. This odor ("stink" is more descriptive) goes away after
several minutes, only to return each time I turn on the air conditioner.
I've tried air-freshener sprays, but they just introduce a new dimension to
the problem. I'd love to take care of this problem before next summer. Any
ideas? -- Edgar

TOM: Well, my guess is you've got yourself a little mold-spore farm there,
Edgar. Congratulations.

RAY: There's a part of the air conditioner called the evaporator, which
removes the moisture from the air (i.e., "conditions" it). That moisture is
then supposed to drain out through a hole in the bottom of the evaporator
housing. That's why you often see water dripping out from underneath cars
in the summertime.

TOM: My guess is that you don't see much water dripping out the bottom of
your car, Edgar, because your drain hole is all plugged up. That's
preventing water from escaping, and creating the perfect breeding ground
for mold spores; a dark place with standing water.

RAY: You need to have somebody clear out the evaporator drain for you. It's
an easy job and is usually done with compressed air. Then you'd be wise to
spray something in the vents to kill the remaining mold spores. There are
automotive products specifically designed for this purpose, but consumer
products like Lysol seem to work just as well.

TOM: And if that doesn't work, Edgar, then I'd start asking around to see
if any of your neighbors cats HAVE misplaced their litter box.

* * *

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