Why is my car's AC not working?

I have a 97 Jetta and my AC has not worked since I bought it a year back. I some what know how cars work, I'm an expert when it comes to brakes, suspension, minor engine tune ups such as oil chances, spark plug replacement and intake problems but I know nothing about AC systems just the main parts of them but much less about what could be wrong with mine. Im pretty sure that my system has freeon in it because a pressure guage was hooked up and it read full, Im also pretty sure that my compressor is still working because when i turn on the AC the compressor kicks on and i can feel the engine bog down as all cars do when it kicks on. I know there is an accumulator and condenser and maybe a few other parts but what could be the problem. Im so close to just taking it in to get it checked out be l have my own tools and know very well how to use them. Does anyone have any ideas to keep me out of the heat? Thanks for taking time to look this over