Looking to replace fan regulator on a '96 G20T

For the longest time, my air conditioner only worked on the highest setting (4). Now, just in time for summer, it has completely stopped working completely. I was told by a nissan mechanic that he was 99% sure that the fan regulator was the culprit. I would like to replace it myself. Does anyone know how hard it is to get to, and where it is located?
Thanks