What could be making the air blow out of the passenger side vents instead of the driver side vents when I ise my climate control system?

This is a common gm problem caused by low or no battery voltage (disconnected battery, battery replacement, low or bad battery, corrosion at terminals etc). Go ahead and set the scan tool to erase all codes even if one isn't showing on your tool. This will resolve 99 percent of this type issue. Hvac controller has logic board and loses memory with low/no voltage. It will not work properly till the code is cleared.

2004 Buick LeSabre blows cold air on passenger side but not on driver's side What's wrong?

My 2004 Buick LeSabre does Pringles the same thing, I've had it checked by two different mechanics because the air doesn't blow out very strong it's cold for a while on one side but not the other just doesn't work properly

I had the same problem and decided to dive into it and tear the entire system down and figure it out. I found a damper system in a box with both the a/c and the heater core inside the box. The dampers always blow across the a/c evaporator and are dampered to flow over the heater core (heat exchanger) when temperature calls for heat. Problems occur when the dampers malfunction. They are controlled electrically and sometimes the circuits malfunction. That malfunctioning can be caused by programming issues with these circuits or worn out mechanical parts that allow the dampers to move. The fix is to replace the damper box in many cases. Sometimes you can get lucky by resetting the electronics disconnecting the battery (12 volt source), but most times not. The box is available online for around $400 to $600. And it's a matter of disconnecting plug in cables, screws, etc and wrestling under the dash on your back in a very uncomfortable position for hours. In short if you have this issue you may want to take it to a GM dealer or do like I did and get rid of the car.