So I replaced it with a new fan, added an extra ground, and the fuse still blows. Happens when the fan runs for longer periods of time. How can i find out why the fuse keeps blowing? I can do a lot of car repairs, but this one has me stumped. Thanks to all in advance.

The ballast resistor or the fan's motor is defective. The ballast resistor is much cheaper so replace that first.

so find the hot wire that runs from the fan relay to the fan and change it