This Frustrating Water Leak May Have a Cheap Fix

Dear Car Talk

Dear Car Talk | Sep 08, 2016

Dear Car Talk:

When I'm driving my 2007 Audi Q7, water will pour out from under the console into both the passenger and driver's sides. My carpet is now soaked. No one knows what the problem is. Some say it's the wells that are clogged, but not so. I need advice!

-- Trina

You didn't order the Audi footbath feature, did you?

It sounds like the drain for your AC evaporator is plugged up. When you run the air conditioner, moisture gets removed from the air inside the car. That moisture then collects in the evaporator housing, and is supposed to drain out onto the ground through a small tube under the car. But yours isn't draining.

Over time, the tube can get clogged up by stuff that travels through your ventilation system: dust, pollen, the occasional rodent. Then the housing around the evaporator fills up with water, and when you turn left or right, you suddenly wish you were wearing your waterproof boots.

You can test this theory by starting the car and letting it run in your driveway for half an hour with the AC on. When you look underneath the car, you should see a small puddle of water. If not, that drain is plugged.

Your mechanic will put it up on the lift and clear out that rubber drain using compressed air. He should wear his fireman's hat when he does it, because once he removes the debris, that stored water probably will pour out onto his head.

If you do see water dripping under the car when you do the test, the other possibility is that your sunroof drains are clogged. They also can be cleared out with compressed air, but it's a little more involved.

And if it's neither of those, then you probably have a leak around your windshield seal. But I'd put my money on the AC evaporator drain, Trina, which is the cheapest and easiest to fix. Good luck.

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