Obviously the inside of the box is melted through a little

 

NON OEM fans pulling power thru OEM size fuse. They pull more amps than the stock setup is setup for.

-Chris

 

So shouldn't the circuit on the fuse break?

 

No, it wasn't a short or over rated for the fuse. It was just too much amperage (heat) over time.

-Chris

 

Thanks a lot chris. Wat size fuse do u recommend?

 

I would recommend a separate relay system wired and fused to the battery using the old stock system as a trigger for the relay(s)

Check the manufacturer's rating for max draw for the fans to build the power system accordingly.

-Chris