Mercedes Benz repair: Air condition compressor, definite answer, freon

Question
I have a 1995 E320 124 series Mercedies sedan. I would like to know if my air condition compressor lock up switch is bad when it want cool/ stay on  all the time, and the freon level is correct. If it's bad is it a difficult task to change? Thank you.

Answer
thats too tough to say, it could be a number of things including your a/c/ heater control module, it doesnt sound like an a/c clutch, but if i were to guess without looking at it, i'd first make sure there wasnt air in the freon, then the control unit. but theres no definite answer without having an hour or 2 too see exactly what it is or isnt doing