my blower mototr runs on high speed only
If it is the resistor, how do I fix the problem?

This is an easy fix. Look under the dash on the passenger side and you will see the vacuum motor that operates a door on the heater box. The resistor is to it's left. There will be two screws holding it in and an electrical connection. I had to loosen the two bolts on the vacuum motor and move it over a little to get to one of the screws. Unplug the electrical connection and remove the two screws. It pulls right out. Put in the new one, put in the two screws, plug in the electrical connection, retighten the vacuum motor and you're all done.