There is a lot in recent (and not so resent) archives on both your symtoms and some diagnostic processes.
The main thing is to use your display as an instrument to find the problem. By pressing the "REST" button until a "1" appears on the left, you have entered actual values. Go to the archives for the list of values but by hitting the two "AUTO" buttons one can scroll up and down with item #5 being evap temp. My most common fault for your symptom would show the evap temp sensor at 150deg or more...not a likely event and the controler won't put up with it and withholds AC function.
Bosch Master, ASE Master, L1
33 years MB technician