Electrical Problems Maybe

Hi all vanners, again. I have an electrical problem, maybe, I might have figured it out. Anyways, the previous owner told me his mechanic installed a fuse in place of a fusible link, because P.W.'s kept quitting. Well, it seems as though this mechanic replaced 2 fusible links with a fuse, not sure why both, but when ever I start the van the fuse blows. Having pulled all the wires out from behind brake booster, I think, and stripping all the tape off I can now trace harness based on Haynes manual. As per haynes, the rear window defroster wires, run on same circuit. I then pulled the switch for defroster, and saw a melted terminal. I am going to try 2 30amp fused lines to join the 2 fusible links, and with switch out, see if I can stop blowing fuses. If this doesn't work, would it be alright to run new power supply to the fuse block for the P.W.'s???