Fans appear simple but they need maintenance like everything else mechanical on the ship. so how to clean them:
1st avoid tampering with technical parts like the motors. This in mind don't use water or even damp cloths to wipe the grills and the blades.
I simply unscrewed the grill and used a paper towel for initial wipes, clearing away the grey fluff. Then a dry cloth was sufficient to restore its shine. (Sometimes corrosion can build up on bladed, in which case, use a scouring pad to clean away.)
I went further to cover the silver stickers with black, to suit the other amenities within, TandEadapt.
I think the full job of cleaning all 5 Fans might blow me back to dark hours.