I have an ‘03 limited with a bad servo on the driver’s side. If I have the truck in ACC and then the temp up and down, I can hear the passenger servo operating and see actually see it opening and closing under the dash, while the driver does nothing.

Haven’t actually fixed it yet, but I did address the issue temporarily by unscrewing the arm that swings the servo open or closed, and then pushing it into to the “heat” position so I could get hot air and defrost my windshield last window. That will work temporarily if you just want to get heat in the winter and AC in the summer.

Your post actually reminded me that I need to dig in and find a part, which I should probably do right now since the truck is up on jack stands with the master cylinder out and the lower dash removed.