Dear Car Talk:
We're having a problem with our 2008 Honda Fit. The car runs OK, but there is a sloshing noise when we drive. It sounds like some liquid is moving back and forth up front somewhere. Any ideas? -- Pat and Catherine
Yes. I think there's some liquid moving back and forth up front somewhere, Pat and Catherine.
OK, I'll try to be a little more helpful than that. There's water moving around in the air conditioner's evaporator housing. When you run the air conditioner, moisture is removed from the air. That's one of the ways the AC makes you feel cooler, by decreasing the humidity.
So your car's AC runs your moist air through this thing called an evaporator. And just like on the outside of a lemonade glass in the summertime, when the hot air from inside your car hits the cold evaporator, the water falls out of it. And then, that water is supposed to drain out under your car.
But yours isn't draining -- or it's draining very slowly. So that water just sits in the evaporator housing, and sloshes around when you drive.
If you accumulate a lot of water in there, it'll eventually spill out on your feet when you make a sharp turn and soak your $300 Ferragamo loafers.
But don't worry; this problem is very easy to fix. Just have your mechanic clean out the evaporator drain under the car. It's probably gunked up with the dirt, leaves and dead rodent parts that you've been driving over since 2008. We just use our compressed air hose and blow it out. It takes a couple of minutes.
If you want to confirm our diagnosis, on the next warm day, turn on your air conditioner, let the car run in your driveway for 10 minutes, and then have a look underneath. If you don't see a puddle of water, the drain is plugged. If you DO see some water, it's possible that it's not draining quickly enough, so you still might want to have it blown out.
The alternative explanation is that your sunroof drains are plugged up (if you even have a sunroof). But you'd be more likely to hear that over your head than toward the front of the car, so I'm pretty sure it's your evaporator drain.
Fix it. It's cheap.