It sounds like you're trying to run a mess of fans in parallel off of the aux socket on the radio. I'm assuming that you are running 5v fans. IIRC, these fans combined can pull over an amp and that might be the root of your troubles.

The best way to run fans on a brushless setup is by running them from the lipo pack. If you are running 4S, that is a bit overvoltage for the fans and they might die a bit of an early death. If you are running over 4S, then you'll need a voltage regulator. You can get one from radio shack for about $1. The voltage regulator and do up to 1A and three fans running at 12v won't even come close to the limit.

Check this out...http://www.rc-monster.com/forum/showthread.php?t=5377