how can i fix my ac?

The dash vents are controlled by blend doors that direct air to each vent, and they're controlled by actuators. It sounds like you have a lazy actuator to the right side vent, and you've probably been hearing a clicking sound coming from the dash on that side indicating an actuator and gears trying to set the vent how you want it. Remove the g;ove bxs and see if you can access the actuator from there. If not, the dash might have to be partially removed. You can find videos online that show this process.

Take it to your favorite independent shop and have it checked, who knows you might just need a reset of the HVAC system. I had a Cadillac that would do the same thing once a year, had the system reset and bingo every was fine for another year, then it would do it again, was going to fix it but traded it in.