[olli_tr]

Ok, so probably the compressor clutch doesn't engage. You can see this by looking at the compressor (the serpentine belt goes around it) and switching AC on/off. You should see the "center part" of the compressor start to rotate and stop as you press the AC button. If not, this is likely because there's not enough pressure in the system (could be other reasons of course). On mine the problem was the condenser (it's very often the condenser as that's right in front of the car just behind the cooling fan and gets hit/corrodes over the years) that had developed a leak over the years. After filling the AC the system worked for a month or so, but then the pressure fell enough and it wouldn't start anymore. Replaced the condenser (this is super easy, 30 min job, no special tools needed) and got the AC filled. Works like a charm.

The condenser looked like this (you can see the yellowish color where it leaked):

Replacement part: Valeo 818170 (original was 6456 GK, but of course yours might have different)