I'm completely confused by what this noise could be. I know for sure it isn't the blend door. I replaced it a year ago by cutting through the trim by the drivers side floorboard. It's still accessible and that's not the issue, as the sound is not coming from down there. I certainly didn't hit the heater core, either, so it's not related to the blend door. I replaced the cabin air filter a few weeks ago hoping it would fix it, but it changed nothing. I'll check the fresh air plumbing, but it doesn't do it for any other vents when the fresh air is active, so I doubt it's that, either. My car is garage kept and I don't park under trees, so I can't think of how anything may have wound up in there. The serpentine belt is new, replaced it last month, and I had the compressor replaced today. If I take out the AC compressor fuse, the noise stops, but it just simply isn't possible for both my old AC compressor and my new one to be making the same sound. It sounds like a bearing in a fan, coming from where the windshield meets the dash and can be heard from both inside and outside the vehicle.

If you turn the volume up and hold the speaker up to your ear, or use headphones, you can hear it clearly in the video.

I'm at a loss. Please help me. No one knows what it is and I can't get any help.

 

only thing I can think of would be the tensioner or any other pulley that the belt is on. sure does sound like a pump though.

 

So it's definitely an engine driven accessory, because the noise changes/speeds up as the rpm's increase. Activating the A/C compressor puts more of a strain on the belt, and anything the belt is driving. To me, it sounds like the alternator, or an idler pulley.

 

Had the alternator and tensioner replaced as well as another new AC compressor put on and it's still making the same sound. It's actually getting worse. I'm completely at a loss.

 

Only two items left - water pump & power steering pump.

 

pull the drive belt and see if it stops, run it long enough just to see if it does it and turn off. sorry should have done this first.