Most 914s had a flat piece (sort of a washer) between the fan hub and the fan. 914s with A/C replaced that with the pulley for the A/C. That is
behind the fan.
The
front of the fan has the pulley that drives the alternator. It has nothing to do with the A/C pulley, except if the A/C pulley is left out and not replaced with the washer, the fan won't line up with the alternator pulley.
Here is an exploded drawing:
http://www.pelicanparts.com/914/parts/engine/aircooling_large.htm
The washer is part #15, and that is the part that gets replaced with a pulley to run the A/C. The pulley part of the fan is #12 in that diagram, and that pulley holds the alternator belt. I hope that helps you visualize what goes where.
--DD