Jim, I have jumped it both with the key on and off and the fan didn't come on either time so I don't think it has to do with the fan.

Now, since I replaced the fuse and the car is running and gets hot both fans come on but when I park the car and it's hot only the big fan comes on. So I assume that both the ignition on and off fan circuits are working properly.

Yet still I wonder why it blew the fuse in the first place and so far I am guessing it's the load of the larger fan motor that is wanting to lock up.