W205 C200 Wired AC problem

[frankonline]

My car's AC just acts wired on AUTO setting. When the outside temp is 30 degrees Celsius, if i set the climate control to 24 Celsius it work for a while and just on and off while driving. This makes the people inside cabin sweat and need to lower another 2 degrees to start cooling again. After few more minutes, it again starts to cool lower and makes the cabin hot. Finally if I put it 20 or 18 degrees Celsius it works normally.

The compressor works and blows the ice cold air when it works. But after some time it lowers its cooling power inconsistently regardless of reaching the set temperature.

what can be the issue? Can it be an issue with cabin air temp sensor? If so, where its located?

Thanks