AC blend door not responding

Easy one to deal with. Remove the right rear trim panel. The actuator will be secured with four screws. Before you remove it you may want to feel the heater lines to be sure that hot coolant is getting back to the heater core. Those are run under the right side of the vehicle.

Basically the large trim panel that goes from the rear door to the tailgate.
To remove it you also remove the C pillar D pillar and rear glass trim, it sounds bad but it is not, basically a few screws and push clips. You will need a large torx bit, think it is either a 40 or 45, that is to unbolt the top ring of the seat belt and the bottom of the rear belt.

Start with the D pillar this is the one in the rear corner between the hatch and side glass. Put the seat cushion into the stowed position but leave the back up. Remove the bolt that holds the bottom of the seat belt to the bracket on the side. Gently use a trim stick or flat thin bar and pull the headliner trim along the edge, then remove the screw at the top of the trim panel and gently pry the trim clips free. See D pillar 1 and 2 images.

Next you remove the glass trim panel. This is the one inside the rear 1/4 window. For it you remove two screws at the rear and slip it back off the clips at the top. See glass trim image.

Now remove the C pillar trim. Pop the cover off the top of the seat belt. Unbolt the top belt bracket. Then remove the screw at the top rear corner and gently pull out on the lower edge to disengage the clips and pull it off the locating tab. See C pillar images.

Finally you remove the 1/4 panel trim. Remove the tie down bolt and tie down, remove the screws and the panel will pull free.

All of these images are for the opposite side of the car but the panels are basically mirror images other than the heat/AC being behind the passenger side while the subwoofer is on the drivers side.
Hope that helps.