Air conditioning

Air conditioning is the cooling of indoor air for thermal comfort. In another sense, the term can refer to any form of cooling, heating, ventilation, or disinfection that modifies the condition of air.<ref>ASHRAE Terminology of HVAC&R, ASHRAE, Inc., Atlanta, 1991,</ref> An air conditioner (often referred to as AC or air con.) is an appliance, system, or machine designed to stabilise the air temperature and humidity within an area (used for cooling as well as heating depending on the air properties at a given time), typically using a refrigeration cycle but sometimes using evaporation, commonly for comfort cooling in buildings and motor vehicles.

The concept of air conditioning is known to have been applied in Ancient Rome, where aqueduct water was circulated through the walls of certain houses to cool them. Similar techniques in medieval Persia involved the use of cisterns and wind towers to cool buildings during the hot season. Modern air conditioning emerged from advances in chemistry during the 19th century, and the first large-scale electrical air conditioning was invented and used in 1902 by Willis Haviland Carrier.

Automotive applications

Air conditioning systems are designed to allow the driver and or passengers to feel more comfortable during uncomfortably warm, humid, or hot trips in a vehicle. Cars in hot climates often are fitted with air conditioning. There has been much debate and discussion on what the usage of an air conditioner does to the fuel efficiency of a vehicle. Factors such as wind resistance, aerodynamics and engine power and weight have to be factored into finding the true variance between using the air conditioning system and not using it when figuring out difference in actual gas mileage. Other factors on the impact on the engine and an overall engine heat increase can have an impact on the cooling system of the vehicle.

The Packard Motor Car Company was the first automobile manufacturer to build air conditioners into its cars, beginning in 1939.<ref>Michigan Fast Facts and Trivia, retrieved on 2009-08-29.</ref> These air conditioners were originally optional, and could be installed for an extra $274 (about $4,050 in As of 2007).<ref name=great>"Air Conditioning and Refrigeration Timeline", National Academy of Engineering. Retrieved 2009-08-29.</ref> The system took up half of the entire trunk space, was not very efficient, and had no thermostat or independent shut-off mechanism.<ref>"Air Conditioning and Refrigeration History - part 4", National Academy of Engineering. Retrieved 2009-08-29.</ref> The option was discontinued after 1941.<ref>Template:Citation/core{{#if:|}}</ref>

In 1954, the Nash Ambassador was the first American automobile to boast front-end, fully-integrated heating, ventilating, and air-conditioning system.<ref>{{#if:

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}}.</ref> The Nash-Kelvinator corporation used its experience in refrigeration to introduce the automobile industry's first compact and affordable, single-unit heating and air conditioning system optional for its 1954 Nash models.<ref>Template:Citation/core{{#if:|}}</ref><ref name= albinder>{{#if:Binder

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}}.</ref> This was the first system for the mass market with controls on the dash and an electric clutch.<ref>Template:Citation/core{{#if:|}}</ref> Marketed under the name of "All-Weather Eye", the Nash system was "a good and remarkably inexpensive" system.<ref>Template:Citation/core{{#if:|}}</ref> Entirely incorporated within the engine bay, the combined heating and cooling system had cold air for passengers enter through dash-mounted vents.<ref name= albinder/> Nash's exclusive "remarkable advance" was not only the "sophisticated" unified system, but also its $345 price that beat all other systems.<ref>Template:Citation/core{{#if:|}}</ref>

Most competing systems used a separate heating system and an engine-mounted compressor, driven off of the crankshaft of the engine via a belt, with an evaporator in the car's trunk to deliver cold air through the rear parcel shelf and overhead vents. General Motors made a front mounted air conditioning system optional in 1954 on Pontiacs with a straight-eight engine that added separate controls and air distribution. The alternative layout pioneered by Nash "became established practice and continues to form the basis of the modern and more sophisticated automatic climate control systems."<ref>Template:Citation/core{{#if:|}}</ref>

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.<ref>Template:Citation/core{{#if:|}}</ref> American Motors made air conditioning standard equipment on all AMC Ambassadors starting with the 1968 model year, a first<ref>{{#if:

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}}.</ref> in the mass market with a base price starting at $2,671.<ref>{{#if:

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}}.</ref> By 1969, 54% of the domestic automobiles were equipped with air conditioning, with the system needed not only for passenger comfort, but also to increase the car's resale value.<ref name=great/>

See Also

• HVAC