a/c not cooling. a/c gas is full. what could be the problem?

many things. take it to a pro and have it diagnosed correctly.

Is your compressor operating? If so, then it's the switch that turns your A/C to ON. I'm sure it's all done electrically. It's not switching from HEAT to A/C. If it's just the push of a button to activate your A/C then take it to the dealer. You don't want to start messing with the electronics.

If you know you have a full freon charge and after starting the engine and opening the hood, setting the fan to on and have depressed the ac button and can see the lighted ac on indicator lamp below/next to the climate output port control, check under the hood to see if the electric cooling fan and ac clutch are both on or cycling. In the event that you have neither ac clutch operation or cooling fan, check fuse #5 in the under hood fuse box. If the cooling fan is running and turns on and off if you cycle the ac switch, you will need to check for power at the ac clutch with either a multimeter or 12v trouble light. connect one lead to ground and touch the other to the under hood battery jump post. this is to test and make sure your ground connection on the light or meter is good before proceding. assuming you have a good connection and your light or meter indicates 12v, use the pointed probe to puncture the green wire going to the ac clutch connector but be careful to not stab completely through and short the probe into the compressor body or stab your finger, as neither of those things are advised. If you have voltage there you probably have a clutch winding failure. There are other components that can fail, but the clutches often fail as a result of heat and environmental issues and if the ac fuse is blown, chances are the clutch coil is going to fail soon.