Does the non working fan spin freely by hand? Is it the same as the working one? If it has more drag then your problems are likely mechanical. If it is free like the working one your problems are more likely electrical.

Electrical connections near both motors should be looked at. and at the source connections at the dropping resistors on the fender well behind the drivers side headlight. These get very hot and are prone to corrosion because of the heat of the dropping resistor. Check and tighten the bolts on that, perhaps removing and clean it.

If all is well with both electrical and mechanical , when you fast spin one fan by hand it should rotate the other one slowly because the spun fan creates some current that passes into the second fan. If it does not, you know it either has some mechanical drag or perhaps and electrical disconnect. OR perhaps a worn out motor?