Climate disaster: ACC does not cool

Hello Moose friends, when I got into my heated car after work today (jaaa, finally sun again! ) and switched on the climate automatic, nothing happened , i.e. the air does not cool. Otherwise the speed always slows down at short notice and when driving you notice that a few elks are missing, but also there I noticed nothing. However, I still had the impression that when the climate was switched on you heard a “noise” from the engine compartment. The regulation of the fan works but (automatic control) My car is now 5.5 years old, has run 150,000km, until last autumn the climate went still. Can it be that the refrigerant is out, the climate compressor is therefore not under load and therefore you do not notice the typical climate symptoms (short-term deceleration of the speed, power loss)? Thanks in advance for Tips, Eric