Heat not switching over from defroster

[06SilverS281]

Hey guys I searched and couldn't find answers for the issue im having. just started acting up and its annoying as hell. Stuck on defroster, little bit of heat will come out on vent but not much at all. Floor nothing comes out. What do I have to take apart to get to the door and what do I have to test?

 

[pics06gtstang]

First off make sure the plug has not came loose . from drivers side
take the side panel off @ the center consul and reach behind the a/c cluster and check the first plug . happened to me once for some reason . and untill i plugged it back
in it would just blow a lil air , like a bad blow job !