Weird sound in my car's AC

June 30, 2008 4:47 PM

When I turn on my air conditioning in my car (or any source of air; like the heat, etc.) I can hear a flapping sound, like a plastic bag or something. I'm wondering if anyone knows what that might be caused by, how to fix, where to look, or who to ask. Thanks!
posted by socialpsychologist to Travel & Transportation (8 answers total)

Probably there's a leaf in the air channel.
posted by Class Goat at 5:02 PM on June 30, 2008 [1 favorite]

Seconded. Try switching the fan on full/off/full/off a few times and see if you can shift it.

Otherwise (depending on your perception of the noise) it may be the fan dying a death. Is the flapping noise directly proportional to the speed of the fan?
posted by Brockles at 5:07 PM on June 30, 2008

Best answer: When my air conditioning broke last year the local air con place did a really comprehensive free check to figure out what the problem was (no obligation quote etc). This seemed to be pretty standard for that type of repair place, probably because air con isn't entirely necessary and can be expensive to keep running (so people are a bit more reluctant to get it looked at). Take a look around and see if somewhere near you is offering the same thing, because if it is just a leaf in there (which I bet it is) they'd know where to look and should be able to pull it out during the check so the whole thing wouldn't cost anything. And if it's more serious then at least you know what's up and how much it will cost to fix.

This is all assuming you can't figure out where to look yourself and yank out the leaf or whatever. That would be the first option if possible (and hopefully someone else can help you with that part).
posted by shelleycat at 5:10 PM on June 30, 2008

Clogged condensation drain- the water never drains out and when the fan spins up, it splashes the water. You might also notice that it makes the same sound when turning, accellerating or stopping. And the passenger carpet might be wet.
posted by gjc at 5:31 PM on June 30, 2008

If it's a louder rattle than something leaf-like, check the squirrel-cage thingie for the blower fan. I had this problem once and it ended up being a mouse stuck in there. I didn't figure it out until the smell.
posted by Addlepated at 6:04 PM on June 30, 2008

Thank you so much for asking this. I'm having the *exact* same problem, but I've been way to damn busy to see what's going on under my hood. I figured I probably need a belt-replacement, but I'll force myself to wake up 15 minutes earlier tomorrow and check the recommendations within. If a simple leaf or whatever is all it is, I'll kick myself.
posted by Ufez Jones at 8:57 PM on June 30, 2008

Response by poster: thanks everybody!
i'll be taking a look tomorrow, hopefully it helps!
posted by socialpsychologist at 10:12 PM on June 30, 2008

I would check the fan. In my car (2004 corolla) when something gets stuck in the fan it makes noises like that. IF your car doesnt have an air filter a leaf or something could have gotten sucked in and stuck in the fan for the air conditioner and heat.

Usually just requires taking out the clove box and removing a panel . in ssome cars the ppanel has two tabs and in cases like my gf's car (2002 elantra) there is a screw that has to be removed.
posted by majortom1981 at 5:39 AM on July 1, 2008