An owner has suggested sharing this article from This Old House magazine with advice about cleaning a bathroom fan.

She also includes some other tips:

If you have never cleaned it before, you’re going to find that it’s really disgusting behind that cover on the wall of your bathrooms. There is a list in the article of tools you may need to do this job. The list includes compressed air but you can do it with a vacuum attachment just as well.

This is a great time of year to get these things done. Think of the time change as a time to change the batteries in your smoke detectors, clean your bathroom exhaust fans, and change out the filters in your heat pumps; all measures that keep these items healthy and running smoothly.