AC temperature control problem (C5 )

Passenger side dial is set in the center default position. No matter where I adjust the driver's side dial the passenger side is blowing ice cold and the driver's side is barely cool at all. What is going on?

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Taking a look at the schematics there are two actuator controls, one each for the driver and passenger that control the temperture. The actuators are on either side of the HVAC module case (the air plenum inside the car). Both actuators are controlled by the HVAC Control Assembly which is the module that has the HVAC controls. The actuators and control module share the same fuse, so it's not likely that their is a power issue. The shop manual also says that a code should be set if problems with the HVAC control assembly are detected. Do you have any codes? To read the codes on a C5 do the following:
1) turn on the ignition but don't start the engine. 2) press the "reset" button to turn off any warning messages 3) press and hold "options" and 4) while holding "options", press "fuel" four times within a 10-second period.
The shop manual does describe a process where the HVAC control can "re-calibrate" the actuators (usually after one of them has been replaced) which is done by pulling the HVAC fuse (#27) and putting it back. It says this process takes about 60 seconds and each actuator is moved from fully open to fully closed to calibrate them. If this doesn't fix the problem you could have a loose connection on the HVAC control module, or the control module is bad.

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