WHISLING noise whenever i start up my m3???

[b m w m 3]

Hey does anyone know what this whistleing noise is whenever i start my 99 m3 it makes it for about 10 to 15 seconds.....i think it may have something to do with the air (a.c) as it stops when i turn off the air after it always comes on when i start it up automatically.
anyone know ?

[racer m]

http://forums.bimmerforums.com/forum/showthread.php?t=938702&page=2

[JuM3]

pully. my best guess.

[BaltimoreBimmer]

Secondary Air pump is a thought.

[cosM3os]

Turbo.

[M///BMW]

Secondary Air pump is a thought.

+1.

[Unleashed603]

the whistles go wooo....

[Mstngcobr761]

mine was doing this...then my tensioner pulley grenaded itself couple days later

[Volf]

Turbo.

:rofl:

[M///BMW]

Turbo.

I'm pretty sure a whistling sound comes from a supercharger.

[cosM3os]

Nah, that's more of a whine.