Why isnt my ac working on the left side

A common reason for this fault is the actuator for the blend doors. On pretty much any reasonably modern car they do not use mechanical doors like they did for years; they use a blend door and an actuator. This is a dash out job on any of these cars, so be prepared to spend a day on this repair. At a shop, this is a $20-50 part, and it's mostly labor.

This is what the part looks like:

If that is not it, you may have an issue with the A/C motor or the resistor on the motor. Start with the blower actuator and work your way down as it sounds like an actuator issue based on the other side working. Now if both sides had an issue I'd be inclined to suspect the resistor or motor under the glovebox.