I had the exact same problem on my '96 Dak. Check out this pic, yours is probably the same or at least pretty close. See the connector with the hole in it? Somehow it got hot, melted the plastic, and it ended up insulating that lug.
I just pulled the harness, scraped all the connectors both male and female, hooked it back up, and voila! Instant blower motor.
Hope this helps.