You should start by seeing if the clutch is kicking in. The compressor is low on the drivers side. Have an assistant turn on the a/c with engine running as you watch the very front of the compressor. The very front portion will not be turning, but should turn when the assistant presses the button.

The only a/c shop that I know that I can recommend is McCains on Floyd Circle near the main Texas Instruments plant in Richardson. They are very good and honest. Their phone is 972 669 0669.

Good luck,