I agree. There are many factors other than just AC Compressor that contribute in heating of Engine like:
1- Tight Clutch Wire that puts load on engine through pressure plate
2- Alignment/Cambering of Front Tyres (in case of Mehran)
3- Fake/Poor Quality Coolant
4- Hose Pipes Bent, Radiator not serviced for long, Low Fan speed etc.
But the main thing for engine cooling is the Condensor. Problem is its just in front of Radiator making things worse. I am not sure whether it could be re-fitted in some adjacent space so that it doesnt come in Radiator's way at all. An additional fan installed along with necessary relays in front of it could boost the cooling.