Same problem on my 98. Don't think its the **** controller as that is a simple rheostat. I took the door actuator off and found the door works fine. Opened up the actuator plastic and the gears move fine by hand, but no movement from the motor when **** is adjusted. I am assuming that power is fine and its just the motor that's blown. Everything seems to work mechanically.
As a temporary (summer) fix, I moved the door to block the heat and reinstalled the actuator to lock it closed. So now I have full cold AC, but no heat.
For the 98, the actuator is Dorman #604205, $38 at RockAuto.com (not a plug, just my general first resource for parts).
Removing the floor vent and getting the actuator out was a pain in the butt. There's hexhead screw way back under for the floor vent, and 3 for the actuator.
Hope that helps.