Car is 2010 Gmc acadia slt. I had a post earlier about question whether the battery, alternator, or both were bad. Got it all fixed. It ended up being just the alternator. I drove it home, and the next time I went to drive the car in the 95 degree weather. the drivers side 2 left vents were blowing hot. Everything else blew cold. No matter what I changed it stayed hot on the 2 drivers side vents. The mechanic wanted to charge me a diagnostic fee, and like 50 dollars for the actuator. I told him no and just shot off those 2 vents. I came home and searched on the computer about it. There was a write up about resyncing the actuator. It wasnt for an acadia, but it was a gm, and had the digital controls. So i said why not. I wrote down the directions, and it said to turn key on, and set the controls to auto. then turn off the key, and remove the hvac fuse under the hood. Well I couldnt find one under the hood, but found one under the dash on passenger side. Anyways remove that for for 1 minute, and then reinstall, and start the car for 1-2 minutes, and then shut it off for 10-30 seconds, and it should be resynced. I did that and it worked and was blowing ice cold air, and would switch to whatever settings I wanted. Well it last just a couple days and it is blowing hot air again. I tried to do the resync thing again, and it doesnt work. Does anyone know if that is the proper way to resync the actuators in the acadia, or was it just a fluke thing for me, and how do I know if the actuator is just bad? How tough is it to change the one on the drivers side vents? Thanks for any help.