Buzzing noise when put into reverse

[RhysQ]

hey guys (and a few girls),

i only noticed the other day that when i put the car in to and out of reverse there is a quiet buzzing noise coming from the passenger side. it lasts for about 3 seconds and it sounds as though there is a motor in the passenger side mirror to tilt it up/down when reversing (but the mirror does not move).

anyone know what it is??

Cheers,
Rhys

[Bubu]

I read somewhere (probably on this forum) that when you put it in reverse the vents that allow fresh air close. This is apparently done so that you dont get exhaust fumes in the car. So that may explain the noise you hear.

[VW GTI]

I was going to say that I've never heard it, I always keep my air vents closed, so that might be it (and why I don't here it).

[DaveMack]

If your aircon is running when you put it into reverse, Bubu is quite right ... it changes to 'recycle' to ensure exhaust fumes are kept out.

Dave

[RhysQ]

i never really have my air con on but much the same, it is not set to recycle so that would explain the noise....cheers ppl