Air Conditioning problem on 2005 Buick Century

Seperte slide cotrol for the driver and passenger sides. Cold air comes from the passenger side vent but does not from the driver side. The dealer has never given us a definative answer as to the problem. Can anyone let me know the answer?

Asked by for the 2005 Buick Century
I've been experiencing the exact same problem for over 3 months now until it finally got so hot I had to take it to my mechanic. He said the r134 which cools goes bad after so long and you have to vacuum the old 134 out and put new in. I just had it done this morning and my AC is so cold it's freezing me out and its a hundred and five degrees outside today. So its not a filter issue its not a compressor issue it's not an actuator door opening and closing issue its a cooling issue they all 134 goes bad and the car just blows around stale warm air! Problem solved.