Nash "became established practice and continues to form the basis of the modern and more sophisticated automatic climate control systems." Growth in application The innovation was adopted quickly and by 1960 about 20% of all cars in the U.S. had air-conditioning, with the percentage increasing to 80% in the warm areas of the Southwest. Cadillac introduced the industry's first Comfort Control which was a completely automatic heating and cooling system set by dial thermostat for the 1964 model year. American Motors Corporation (AMC) made air conditioning standard equipment on all AMC Ambassadors starting with the 1968 model year, an innovation in the mass market with the base prices of the cars starting at $2,671. At the time, air conditioning was standard only on Cadillac limousines and Rolls-Royces. By 1969, 54% of domestic automobiles were equipped with air conditioning, a feature needed not only for passenger comfort, but also to increase the car's resale value. Air-conditioning for automobiles came into widespread use from the 1980s. Evaporative cooling A car cooler is an automobile evaporative cooler, sometimes referred to as a swamp cooler. Most are aftermarket relatively inexpensive accessories consisting of an external window-mounted metal cylinder without moving parts, but internal under dashboard or center floor units with an electric fan are available. It was an early type of automobile air conditioner and is not used in modern cars relying on refrigerative systems to cool the interior. To cool the air it used latent heat (in other words, cooling by water evaporation). Water inside the device evaporates and in the process transfers heat from the surrounding air. The cool moisture-laden air is then directed to the inside of the car. The evaporate "cooling" effect decreases with humidity because the air is already saturated with water. Therefore, the lower the humidity, such as in dry desert regions, the better the system works. Car coolers were popular, especially among summer tourists visiting or crossing the southwestern United States states of California, Arizona, Texas, New Mexico, and Nevada. Operating principles In the refrigeration cycle, heat is transported from the passenger compartment to the environment. A refrigerator is an example of such a system, as it transports the heat out of the interior and into the ambient environment. Circulating refrigerant gas vapor (which also carries the compressor lubricant oil across the system along with it) from the evaporator enters the gas compressor in the engine bay,