When my auto AC kicks to full blast I have a loud sound from the blower. It sounds a lot like a lawnmower or when you put a baseball card in the spokes of your bike as a kid. When I lower the blower to about half it goes away. Any ideas?

Uht Oh.... That's the sound it makes when you have a cracked intermediate shaft.

Ok, just kidding. That was mean. Sorry. How many miles on your car? Have you changed the cabin filter yet? It sounds like something got inside your airbox. Maybe a leaf or something. But that's hard to get past the cabin filter. Try turning the recirculate on and off, any difference? I need more clues.

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Gator Bite
(View My Articles : Blogs : Car : Profile)

GatorBite is right on it. I've had that in other cars and it was a leaf. Drove me crazy.

Don't know how it could have gotten past the filter.

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Robert

i thought you were supercharged and complaing about the sound from that blower. Thinking to myself that you were crazy for that but then i read

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2004 BMW 745Li (Sterling Grey)
2006 Porsche Cayman S (Seal Grey)

Hmm, interesting thought. I have about 6k miles now. I have not changed the cabin filter, did not even know about it. Does that help?

Actually, if the cabin filter is real dirty it can cause some strange sounds. It's possible that yours is dirty, which could cause whistles, vibrations, etc... as air leaks around it or tries to.

I think they recommend changing it at 20,000, but if you live in a dusty area, it can clog up much faster.

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Gator Bite
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I'm with Robert and Gator Bite. A leaf got stuck in the blower of another car that I had. It sounded like a playing card in bicycle spokes.

It takes 15-30 minutes. Here is the procedure:

1. Remove the wipers. Use masking tape or blue painters tape to mark the location of the blade tips. This makes it easier to reinstall the blades correctly. The wipers are held on by a single nut, hidden under a removable cap which pops off quite easily. Pull straight out on the wiper being careful not to scratch the hood. You may have to rock the wiper back and forth a little but it comes off with not much effort.

2. Remove the battery cover and the two covers on either side of the battery cover.

3. With a long common screwdriver, prise up the top of the two plastic rivets immediately behind the battery. Remove the rivet top from it's housing completely (I used long needle-nosed pliers, pulling straight up). Then, using the same long screwdriver, push up from underneath the rivet housing to dislodge it. This is easier done than said. There is no need to remove the battery. Disconnect the rubber hose connecting the washer reservoir to the spray nozzles. This is adjacent to the driver side rivet mentioned earlier.

4. Disconnect the two electrical plugs adjacent to the rivets.

5. There are two caps that hide two nuts which secure the windshield facia. The caps are located at the outboard ends of the fascia. Pop off the caps and remove the two nuts, spring washers, and trapezoidal washers. Pay attention to the order of assembly or take a pic.

6. Remove the single Torx screw in the center of the fascia.

7. Lift the fascia up, gently manipulating it off of the car. It will require alternating the position of the trunk lid.

8. Remove the cabin air filter. With a mirror, you can view the inside of the blower cage to look for anything that might have lodged itself within it's confines. You can also remove the filter housing, but I wouldn't recommend it as the gasket fit is tricky, as is the removal of the screw on the passenger side.

Assembly is, of course, the reversal of removal. Hope this helps!