It's in the fusebox, by the wiper motor, if you lift the lid the one that is smoking and melting is the guilty suspect, the fuse for this also melts it's holder in the same fusebox.
They really are very crap.
Most sensible/safest solution is just discard oe wiring for fan, and make yourself a new mini loom/relay for the fans, the ford stuff is worse than crap.
tabetha