Guys, I have been working to resolve an issue with the mode door on our 2002 GMC Envoy XL. I have replaced the actuator several times with mixed results but always ending up inoperable. I have not used a genuine GM part yet but the next one will be. I believe the part number is 89018539. Each time I replaced the part it would function for a short time and then default to blowing onto the floor only. I now have a Tech2 clone and will be working on trying to figure this out. I was messing with it this morning and can command the fan on and off as well as command the recirculate door to open or close but none of the other commands do anything and the control doesn't seem to want to go into calibration mode. In fact I can t determine which command is for the mode door as there is no actuator listed a such. Any experiences to share? I will try again soon and upload some photos or videos of what I am seeing.