Recently after I noticed that the AC of my ML320 (98) was kinda warm (even hot in hot weather) when in idle or stuck in traffic. I kinda noticed that the compressor was off (perhaps the correct term was the compressor clutch was diengaged) at idle and would turn on at a higher RPM but not at idle RPM

Is there a way to test this and if i confirmt that the compressor is idle is there a way for me to adjust it so that the AC compressor is on at idle?

Yes i made sure that the temp dial was turned all the way to the cool (left) side. I also made sure that the compressor is in the on position (unless it has econo mode like my mitsubishi pajero).