For karachi market @Xulfiqar, @capsat can guide you better.
Since your car ac is cooling satisfactorily until it gets tripped, so there may not be any issue with the compressor itself. There is actually some safety feature which is not letting the refrigeration cycle to continue. I don't know much about Grande ac, but in older cars the ac will trip under some of the following conditions:
a. Compressor over heats
b. Line pressure is too low or too high
c. Required temperature is achieved inside the cabin
To investigate the problem the ac technician shall attach manifold gauge set with your car ac, with compressor running he shall check the working pressures, if those readings seem abnormal then he has to release some refrigerant to get back in the safe working limits.
However, I would suggest you to first check the ac cabin filter, must be there under the dash near glove box area, thoroughly clean it with a blower and recheck if the system works fine or not. As restricted flow through the evaporator coil may lead to early tripping of compressor.
