I had this happen to my 98.
I also thought the switch was bad. However after taking it apart I later figured out what was the real problem.
You need to locate the A/C blower motor "resistor pack". This part hides behind the blower to the left and is also behind the glove box. It's sort of in the firewall, but really in a plastic chamber to keep it cold. I think on mine it's a white plastic? There should be some wires that plug into this sucker and it's these wires that normally burn up.
What I did was strip off the melted wire connector going to the resister pack and colored each wire with tape so I could put them back in order. Then I got some female (Or Male?) wire connectors at Radioshack and wired them on the ends. Then I just plugged them into the resistor packs metal plugs and was running cool ever since.
Some times the switchs and resistor packs do go bad. You can pick these up at any local junk yard far cheaper than buying them retail. However, check out the wires going to the resistor pack first because this is the problem 99% of the time.
