flex-a-lite fan problem

ok heres my problem..... i have teh fan wired up for a while now, couple months... was working fine... its on a inline fuse to the adjustable t-stat it had a 20 amp fuse in it... well all of a sudden it started popping the inline fuse.. im not sure where to go with this...

if i take the blade off the fan it doesnt pop the fuse.. put the blade on and it does..... if i put a 25 amp in there it works fine.. im just htinking a 25 amp fuse is a pretty big fuse for a fan...

anyone else have this problem with a flex-a-lite..????????????

Trevor