The air conditioning blows in the rear, but not in the front of the car.
The AC air blend doors on these vehicles, and on most GM vehicles, now have electronic blend door control solenoids that seem to go bad pretty often; this sounds like the problem you are having. I recommend that you have a mechanic, such as one from YourMechanic, come by and inspect your AC system, including your AC blower controls, and verify the repairs needed.
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