Strange sound

[rocketjacket]

I have noticed an extra fan sound when I am driving, almost sounds like extra revs when I am driving. It disappears and comes back randomly. I cant hear it over the normal engine noise, only when I am driving slow or at the traffic lights. Any ideas?

[CTScott]

Are you sure it isn't the cooling fan? It will run more at lower speeds, or when stopped.

[rocketjacket]

How can I tell if its the cooling fan?