Just did my first repair on my '99 rover: light bulb replacement in the clock and climate controller. Up next is the noisy dash fan and the power steering pump. Free online repair manual is great!

 

Praise the Rover gods, you already have the RAVE! By dash fan if you mean the main fan for the heat / AC, it can make noise when full of leaves and trash. See page 80-24 in the workshop manual under heating and ventilation. But fixing issues one at a time - you may want to consider some proactive things, like front propshaft rebuild. There is a write up for that in our tech section, with photos.

 

The fan is the little fan just below and to the left of the steering wheel. This thing looks like a computer cooling fan and is full of dust. I blew it out and it is even louder. I identified the noise when I realized the fan turned on when the key was in II position. I also found a thread on the issue early this week.
As for the front propshaft rebuild. I place I purchased it had it replaced because of some reported grinding noise. I am not sure about the details. What should I look for when crawling underneath?
The other thing that I found is that the rear radius arm bushes are LOUD when going over large bumps. Three on each arm, I think it is the front ones. RAVE 64-31 goes over the replacement. I have been spraying them with silicone which seems to have reduced the noise a bit. Maybe I am imagining things, but I am going to keep spraying them until they shut up or I do the replacement.