I found an old post telling me about the resistor problem that usually
results in the blower only working on high because the higher setting
does not need the resistor.
After an hour of analysis looking at replacing the blower, I decided to
look for this resistor bank.
Some posts said it was under the dash. However, on my 96 Dodge Dakota
2WD truck, I found that there is a 6 wire connector under the hood, on
the firewall, just under where the hood seats, on the passenger side of
the pickup. I had read that the wire to worry about was tan and black.
I found the connector but couldn't get the supposed resisitor bank to
unscrew from the firewall. However, the center top wire on the
connector was damaged. It had gotten wet. The plastic was arc'd away
from the connector and the connector was rusted on the male and female
side. Looks like the hood seal wears out and leaks over the top of
this connector. The water drips right down on this connector.
I am going to repair the hood seal, clean the rusty connector pins on
both sides, and use electrical tape over the connector to make sure it
doesn't get wet again.