2010 GMC Acadia Heater

Try pulling fuse for hvac inside car first with key on. Leave it out for 60 seconds then reinstall it may reset the actuators. If that doesn't work see if actuators are getting power, it may be a bad actuator if no power then get it scanned for codes by a pro. It may be the control head

Thanks a lot! I will try those options and let you know how it went.

Well, I'm actually sitting in her car right now. I tried resetting it and now I'm not sure what exactly was wrong when my wife told me, but now the heat works only on the drivers side and is blowing out of the floor and defrost vents. The passenger side only blows cold air. Also, it won't change to different vent selection. It only blows out of the defrost and floor vents on both sides, but the temp only works on drivers side.
I know that the actuator on the passenger side, controlled the vent selection, but does it have anything to do with the temp for the passenger side? I don't think it does, but I really don't know. If not, what controls the temp for the passenger side? Could there be something wrong or disconnected behind the actual temp control console? I was going to take it apart, but then I thought I'm gonna ask you first to see if there's even a chance of that happening.

From your explanation it sounds like it is not an actuator. There are two shown in pic one arrow is for right side heat and two arrow is for direction or mode. Try the reset one more time turn key on pull hvac fuse inside truck and leave it for 60 seconds. It can take for another minute for the actuators to reset so don't turn key off. If it continues what it is doing then take to a local pro and have it scanned for codes because it may be a control head or one of the doors have broken.