95 LHS 3.5lt

Ok here is the problem. The a/c doesn't work (bought it used), but when any of the a/c controls were pushed ( window defrost) you could hear the fans (rad fans) running. Well they have stopped running and it over heated one day. I checked the 40 amp fuse and it was blown so I replaced it. The fans didn't come on with the a/c buttons but it did come on when the car got hot (perfect). Well since then the car over heated again and I checked the fuse and it was blown again. Once more I replaced the fuse but this time I dissconnected one of the fans (thought maybe it was drawing to much juice) and when the car gets hot it comes on and cools it down.
My question is: Is there anything else that might be causing the fan fuse(40 amp) to blow? I know the fan it working ok by itself but with 2 fans running it cools down faster.
Both fans turn freely so I didn't think it was ceesed.

Start looking for shorts or naked wires.