damonoresky

The other day I started my car and there was a super high pitch sound coming from somewhere behind the center dash console. It lasted about 30 seconds before it stopped. When the car is warm it seems to be less and less in duration and sound. Everything seems to operate normally.

It was really seriously making my ear drums bleed. What the heck is going on??

I have a 1991 S4 auto with 45k miles.

awdmoke

If HVAC is turned on, then possibly blower fan bearing, or if it happens when turned off (like mine does) then you have a vacuum leak to/in the HVAC system.