When I bought it I had this really annoying hissing noise coming from somewhere on my car, getting louder on acceleration. Took me ages to narrow it down to this vacuum hose. But with a good clean and a little regiging with some tape cured it and it’s been silent ever since. (Probable why it’s disconnected)
I believe it’s to do with the climate control and re-circulation of air in the cabin.
Originally Posted by grr