1967 Cadillac Coupe deVille
The oldest car I owned with factory air was a pristine 1967 Coupe deVille I bought in 1982 with just 30 kmiles, here in Buenos Aires. The odometer was in kilometers, and it reached 200! It was a fully loaded car (I'd never seen a car with so many Factory options before), and the air conditioning was automatic, you could select the inside temperature with a rotating wheel, and you would get cold or hot air as needed to keep that temperature, automatically.
The system had a constant running Frigidaire compressor. The cold output of the system was regulated by a closing (choking) refrigerant valve in the suction pipe of the compressor, which restricted the refrigerant flow when less cold was needed inside the car. This was achieved by a bulb sensor attached to the discharge side of the evaporator. As this pipe started to reach temperatures close to 32 °F the suction valve would start closing, choking the compresor of refrigerant, diminishing its output, in order to avoid the evaporator from freezing up. It worked flawlessly!
Emilio