AC dont work! where to start??

Hi

my air con does not work it was not the problem during the winter but now it becomes another big issue for me

black leather black rooth, 25'C+ and sun the perfect condition to sit in the car without air con ...

anyways, where do i start fixing it? )should i hear click when i turn the AC button? or have a change in rpms? so far neither first nor second. Belt is in proper place, Compressor turns but nothing..

i turned air con on, and looked in that receiver- dryer tiny window and nothing is there, just emptyness...

i would like to see if my system operates properly before going and adding the refrigerator into it.

anyone can gimme good advice?
heater seems to be working fine, and everything blows well but only warm and hot air...

i tried to run self diagnostic, but got code 00, which supposed to mean that everything is fine, but its not!
(air con never worked, and it could be cause of engine rebuilt in 2001 but who knows