So I recently bought a 2006 tc and noticed when i go past 60mph, there begins to become a whistling sound from inside the car. I wasn’t sure where it was coming from but it can be heard from outside the car as well. I only noticed today that when going 60+ more and more air begins to come out the vents inside the car even when the ac is turned off. Has anyone had this issue or know what it may be? Thank you guys.

 

Your cabin air vents have foam weather stripping to seal out tramp air. The foam dry riots over time and cracks. Eventually chunks begin to fall out.

So long as your recirculation button is off, air is supposed to flow through the vents. Even when the AC is turned off. Air flowing through the vents shouldn't cause a whistling noise. In your case, outside air may be flowing through cracks in the foam insulation. This might be the source of the whistling.

You can remove the "waterfall" panel to expose the two center vents. There, you should be able to see whether foam insulation has shelled out. If so, you can improvise repair(s) with weather stripping from the hardware store. You might even get away with duct tape.

If that's not the problem, an empty paper towel tube might help isolate the sound. When you hear the whistling sound, get a front seat passenger to point the tube at the supposed source, then listen through the other end of the tube and pinpoint the location(s). Then you could strike a butane lighter to see if it flickers, indicating air flow. Again, a piece of duct tape might be all you need to stop the whistling.