Look behind the glovebox from underneath
3 screws, a small corrugated pipe and an electrical connector and the fan will come out
You will probably find some leaves and other stuff in the fan.
Prise the cap off of the bottom and drip some odourless oil into the bearing (even some veg oil will do) and leave it upside down for an hour or two for the oil to penetrate
I did ours 2 years ago and it is still quiet.