A cloud of white smoke blasts through the vents when I turn the AC on.

Dear Car Talk

Dear Car Talk | Nov 01, 1998

Dear Tom and Ray:

I park every day 50 feet from where Bill Gates parks his Lexus. I enjoy having
my beat-up little 1990 Pontiac 6000 parked wheel-to-wheel with those foreign,
luxury, millionaire, non-previously-owned vehicles! Lately I've noticed a
noxious odor coming through the air vents to intoxicate me. My darling husband
of less than a year thinks it's something dripping onto the exhaust manifold.
Also, recently, when the weather suddenly turned hot, as I was driving home, I
blasted the air conditioner, and a cloud of stuff came out of the vents at me.
It was white and looked just like a cloud. It didn't smell like anything. Are
these two events related? Buying a new car or foreign car is not an option for
me. -- Maryanne

TOM: Not to worry, Maryanne. I don't think you need to buy a new car because of
this. You can go right on embarrassing Mr. Gates and his highest-ranking
executives in the Microsoft parking lot.

RAY: You have two problems. Your husband's probably right about the first one.
An acrid odor coming in through the vents is often due to oil dripping onto some
part of the hot exhaust system.

TOM: You want to get that taken care of for two reasons. One, it's probably
toxic and may be impairing your mental capacities. In fact, you're probably the
one responsible for making my Internet Explorer crash!

RAY: The second reason you want to fix it is because you're losing oil, and your
little Pontiac won't last long if you run too low or out of oil.

TOM: The other problem is a meteorological one. You simply created a San
Francisco-like weather pattern in your duct vents. You had some hot air in
there, and when the cool, dry air came blasting out of the air conditioner, the
moisture in the hot air condensed and formed a cloud.

RAY: It didn't smell because it was just water vapor. But if you can get enough
hot air in those vents, you might be able to make it rain inside your little
Pontiac. Wouldn't that be exciting!

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