okey, i made some updates today, 4 different skintones and 4 animations titled "idle" "fast" "slow" and "stop".
Moreover like Void and stevethepocket mentioned you have to
set the Default Animation" to one of the above mentioned animations and use a prop_dynamic or else it won't spin ingame. best advice would be to use the model viewer to see the animation speeds

on top of that i included a sloppy hammer file, that shall illustrate how could use the fan model ingame. but i guess it's against every mapping law in the world, so bare with me. guess i'll remove the reference map in the final release
on top of that, i have a question to you mappers. Void asked me to do an alternative collision box that only includes the outer lip and the rotor machine inside the actual fan blades. he said that'll result in better shadow casting for him. would every other mapper need that as well ? or shall i leave the collision box as it is ? and would you want the outer lip as big as in voids example ? it's sized as the sewer_cap model now. better, Terr ?
Download:
http://acumen-design.de/projects/show/fan.rar
Void-Alteration
Skin-Variation