I've got an '01 s60, and in colder weather only, the fan blower knocks. I've had this in other cars, and I remember having to take out the blower and clean the cage.
Would that be the problem here? The Volvo, unlike my other car, seems to be "mouse proof", so I don't see why the cage would have debris in it.
If this is the solution, how hard is it to do the job (and where is the blower, for that matter)?
Thanks, Paul