Just went through all of this. Thread probably on next page. Do all your modes work/switch? Face vent, lower, defrost+lower? Sounds like your blend door for top isn't working but the lower (same linkage also controls heater valve) does. I can show you pictures of what everything looks like in and out of the car. (gathered while researching). For me, my lower blend isn't working. Had to disconnect rod from heater valve, open manually, and haven't yet messed with the motor or blend door.