I thought I had an engine rattle (sounds like the sticking valve my ancient Chevy used to get). Not noticeable while driving, but annoying when at idle. I finally realized it was the blower in the ventilation system; sounds like a bad bearing. My dealer replaced the blower, and the new one has exactly the same noise. The Dealer checked out another S7 on the lot, and the same noise. Anyone else run into this, or is yours quiet?

 

Mine is quiet but I had a BMW with that problem. It was the bearing in the blower. I verified this by checking the blower at different speeds and checked the sound of the rattle. Annoying. What. It wasn't much of an issue as I used to keep the blower at lower speeds, told the next owner who didn't care.