Bryuts

I have an 07 chevy trailblazer. My ac controller has a temperature option for driver and passenger sides seperately. with controller set to ac at both sides only the drivers side will blow cold air. the rear ac blows hot as well. I tried the actuator relearn procedures, and the passenger and rear ac still blows hot air. if I have the key in the on position, I can move the temp control and hear the blend door for the driver side opening and closing. when I do this on the passenger side temp control I can not hear any movement from the blend door actuator. I suspect it's either a bad blend door actuator or ac controller. how do I determine which one it may be or even if it's a wiring issue? also is the rear ac connected to the passenger settings?