did this happen to have a "do it yerself" manual fan switch installed somewhere?
if so, thats a common problem because people will jump to the wrong ground & power contact and it causes the relay to melt and feedback to the relay plug where the pins get hot and melts/burns the plastic.
Or, the relay failed on its own and the pins just got too hot. Find yourself a new plug, solder it in with heat-shrink and a new relay. Some auto parts stores have a line of plugs (pig-tails) for GM, Ford or other makes. The plugs are often generic but will be listed with the relays. Be sure they offer the correct relay, main fan or aux, whatever the case. If you have the old one, getting the number off of it is the simplest way to get the correct replacement. parts guys are famous for not trying real hard when confronted with a list of 30 possible relays...and they're always listed under some part name that normal humans would'nt use.
