It should be just one resistor. Easiest access is to yank the driver's headlight out. There may be a gum wrapper in there as the terminals are exposed. Before I'd play there, hook the fan direct to a decent battery and see what kind of current draw there is with a decent ammeter. I'd suspect the fans are full-o-crud and need a good clean and lube. Check the brushes while your there and give a good spray with contact cleaner.

You might also look at the aux fan relay. It is in the relay box behind the fuse box. There are two long ones in a row, it is the back one.