Air conditioning in cars was pioneered by Packard in 1939/40. By the early fifties they were available on most American cars.
The first Japanese car with a factory fitted A/C in Pakistan was the 1967 Toyota Corona.
Mercedes did offer an A/C system for their 1964 220 SE in Pakistan but the first system I remember is the 1967 230S with factory A/C.
The oldest company in the aftermarket or non factory fitted A/C business in Pakistan is the Mark IV Company, situated off Khalid Bin Waleed Road. These guys set up shop in 1964.