Cooling Fan Sound Question

[Bimmerphile4]

When the engine is warm, I often hear what sounds like a cooling fan. The speed of the fan seems to rise and fall with the engine rpms. I theorize that instead of an electrical fan, the cooling fan has some kind of clutch or servo that connects it to the engine when it needs to cool the engine. Is this correct, or am I imagining things? I swear the cooling fan. Thanks for de-mystifying this for me!

 

[NZ00Z3]

Yes the cooling fan has a clutch. There is also a 2 speed electric fan on the front of the radiator that comes on when needed e.g. when ever the air con is turned on or when the temp get high enough.

 

[Bimmerphile4]

Yes the cooling fan has a clutch. There is also a 2 speed electric fan on the front of the radiator that comes on when needed e.g. when ever the air con is turned on or when the temp get high enough.

So are there two fans: one driven and the other electric? Thanks for your help!