The AC is not a dual zone AC. Main controls control all vents, sides, ect. Only the drivers side vents blow cool air. Even with the two middle evnts on the dash, the drivers side middle is cool and the passenger side is not cool. Not hot but not cool either. Almost like the AC is not on and the system is blowing just non cooled air out the passenger side.
AC only cool out of drivers side vents. on 2006 Buick Lucerne
by fredschulz in Ewa Beach, HI on March 11, 2010
ANSWER by Bret Bodas , March 12, 2010
The vent airflow and temperatures are controlled by electric motors, and if one of the motors is acting up it can cause this. However I would l first check diagnostic codes in the climate control module and address those, and check that the software is up to date. Also check for any related technical service bulletins. A good quality shop can perform these types of repairs.