I found this thread when I was having problems with my heater fan (2000 OBS) and it was a big help. I thought I would add my experiences to the thread in case others run into the same problems (also take a look in the electrical section for discussions of the same problem).
Over the past few months my fan stopped running at 1, then at 2, then 3 etc you get the drift. One day it just died. The fuses were fine, so I followed advice here and on other threads on slowly dying fans, figured I needed a new resistor pack, and picked one up at the dealer.
Installation is pretty easy. I pulled the glove box (one plastic screw on the side near the passenger door, five black screws when you open the box [two on each side and one center], I also found it helped to remove one black screw underneath the box on the passenger side this will allow you to pull the whole glove box assembly), two silver screws hold in the resistor pack.
After pulling everything apart, I replaced the pack rehooked up the cable, turned the key, switched on the fan and nothing happened. Great. So, turn everything off and go to the next step I went to the fan motor and tried pulling the connector and reinserting the cable here. Nothing. Next step I pulled the fan motor, it comes out easily with three screws. I cleaned out a few leaf stems, made sure it all turned, and rehooked the cable and tried the fan again just holding the motor in my hand. Success!!
So bottom line: it could be the resistor pack was fine and I just didn't have the cable in tight enough for the fan motor and unplugging and plugging it a few times gave me a better connection, or the leaf stems in the motor housing were enough to screw things up. Anyway this is a pretty easy fix. What ending up taking me the longest was putting the glove box back in.
Hope this is useful.