Pontiac Repair: Heater only works on one side, dual climate, head screws

Question
I have a 2000 Grand Prix GTP. It has dual climate control, but I can only control one side, the drivers side. I have tried to turn the dial, hit 'Auto Control', even played with the vacuum line somewhat under the dash on the actuator. But still cant control the passenger side's temperature. In the summer the a/c blows hot on that side. In the winter it blows cold. Again... only on the passenger side. When I remove the lines under the glove box that connect to the actuator (1 yellow, 1 red)then manually turn the lever, heat will then come out the passenger side but the controls are all wonky. Meaning its set on Defrost but comes out the bottom or vent. Is this a possible easy fix? Like replacing some module? Im sure if I can identify the parts or if you could identify the problem I can fix it myself, but I do not know the names or components that control everything. I asked one other person and he sent me a reply about the actuator, but how much should that lever travel in order to control everything? Or...is it possible to "just" turn or unhook something so that only heat comes out for now??

Answer
Hi Scott:

This has a bad temp actuator like the other person told you It is an electric motor on the heater box. ther are 2 of them one on each side of the box. 9 times ot of 10 int the actuator and not the control head. It's pretty common that they go bad. You can take it off the box but the door will flop back and forth and not stay in one position. It a little black box with 1 wire connector on it It more than likel has 5 or 7 wires in that connector and depnding on the year it has either 2 or 3 7/32" head screws holding onto the box. Any pontiac or chevy dealr should have it in stock . Good luck :}