turn the compressor by hand, if its knocking or rough its bad, test the pressure output compared against ambient temperature and output from the dashboard.
Also make sure the compressor clutch is not worn out and that its airgap is not too large. if it is then the clutch can chatter on and off . In proper working condition the compressor does not trip. Check the clutch magnet resistance - you would need to get under the car and undo the compressor wire - then stick a multimeter probe in the wiring socket on the compressor.
It should be 4 ohms, if its at 4 ohms and the clutch gap is under 0.65mm the compressor should be pumping hard. If the gap is too large the compressor may seem to be tripping. it actually is slipping and will cause the head pressure to go up (loss of cooling) as the proper drive torque is not applied - it will also burn out the thermal fuse in the magnet.
Genuine Denso compressor on this car is about USD 350/- which is about PKR 35,000/- to about Rs 40,000/-. the condenser, drier, and expansion valve account for another USD 250/- the price is about right, but make ABSOLUTE SURE the guy doing the repair knows what he's upto.
In my linked thread I replaced the clutch - MB procedure is to buy a new compressor as the clutch is not a replacement part - But Denso make a rebuilt clutch assy for this compressor which I had to find myself against part number search. Very easy swap though.
Another bit to ensure is that your heater duo valve is not stuck open - it can happen if non-genuine coolant is used, in a diesel the only coolant allowed is BASF Glysantin 05, aka mercedes benz genuine coolant or Valvoline Zerex G05. Otherwise the block can erode at the headgasket joint. Its very oily too.