What's the vacuum hose under dash?

[grr]

There's a vacuum hose coming from the air intake, going through the torpedo wall and in over the drivers foot well, connecting to some kind of a powered switch in the panel over the pedals. Anyone know what it's good for?

It's been disconnected in my car for as long as I've had the car (a few months), because I didn't know about it...

[525SEI BRIT]

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.



There's a vacuum hose coming from the air intake, going through the torpedo wall and in over the drivers foot well, connecting to some kind of a powered switch in the panel over the pedals. Anyone know what it's good for?

It's been disconnected in my car for as long as I've had the car (a few months), because I didn't know about it...

[jani-e34]

Idon't have air conditioning in my car, but have separate temperature controls to the left and right side.
I believe that those are temperature sensors.

[grr]

Hmm, ok.

I've reconnected it, and I haven't heard any hissing noise. The heater core started leaking when the previous owner had the car, so I'm guessing they forgot to reconnect it after the panel was reinstalled...

[A1BMW535iSport]

there is one each side of the car for monitoring temperature

[Dan in NZ]

I don't see why a temperature sensor needs a vacuum hose attached to it...

[Paul in NZ]

don't see why a temperature sensor needs a vacuum hose attached to it

maybe the vacumn moves something in the box??