Specifically I don't know what did the job. However, it seems to me that, all elements within the electical path should be in optimal conducting condition in order to have the most efficient power use and least electrical resistance ie; less heat produced

10-15 + year old fuses will end up with some corrosion. Use quality ATS ceramic fuses (Torpedo style). You'll be better off in the long run.
http://www.littelfuse.com/data/en/Data_Sheets/Littelfuse_Fuse_ATS.pdf

Fan fuse, D***, D*** :mad:
FWIW I just spent many hours and a significant amount of dollars replacing parts that didn't need to be replaced because of the D*** fuse. It was one of the first things I checked, and it looked whole and complete. No problem there! Well, after nothing else worked, and I was trying to figure out how to wire it directly to the battery so it would run but shut off when the engine was turned off, I took another look at the fuse. It still looked good, but I remembered the post about plastic fuses. When I took the fuse out, the metal strap was good, and the plastic holder was good, but the area around the connection where the aluminum and copper meet had heated and the plastic melted just enough to block the connection. It could not be seen except when the fuse was removed! The only indication was some brown (burned?) plastic on the lower portion of the fuse; not even enough to cover the nipple where it joins the copper bracket.
But it now works, and as soon as I get to the Volkswagon dealership, I will buy all new fuses and put them in. ( :) Volkswagon - because german parts is german parts.)

So even if the fuse looks OK, try replacing it with a new one. :o
Many thanks to all who posted on this thred!!

Mine kept blowing fuses, I ended up rewiring the whole thing. Basically ran a relay to the battery and the coolant temp switch to the relay. Although in south florida i'm not sure it matters, fan runs unless i'm on the freeway anyhow.