Ok guys as we have lots of mechanical experts already contributing to this thread with very worthy advice so there is nothing left for input there hence I will be making some real desi totkas on how to live with this problem
1. Use engine braking while city driving.
2. Put the ac blower speed to min while idling.
3. Put the ac condensor fan to direct so that it keeps cooling the radiator even when ac trips.
4. Blow the hot air out first when parked under the direct sunlight.
5. Get a faster condensor fan or even two fans.
6. See that the heater pipes are blocked and not bypassed.
Anyone is welcome to ask why? if he doesn't understand the desi logic behind these totkas