why does my a/c only blow extremely hot air on 2001 Volkswagen Jetta

My a/c compressor kicks on, all plumbing gets ice cold and sweats and the unit is full of freon but all I get is very hot air blowing out of the vents. The car is running at its normal operating temperature of about 190 - 200 degress and no leaks under the hood. It seems I have no control of the temperature with the knob in my dash panel. Was wondering if the heater valve can possibly be the cuplrit and where it is located? Do you think if that is the problem if that can be repaired by a person fairly car smart and handy?

Asked by for the 2001 Volkswagen Jetta
This link has a description and pictures of what one cause can be. I just had this happen to me recently and I used this to fix mine. The area they are describing is in the upper left hand portion (facing forward) of the passenger foot well.!!