Automotive air conditioning

[1] On 7 October 1935, Ralph Peo of Houde Engineering, Buffalo, New York, applied for a patent for an "Air Cooling Unit for Automobiles".

Cars ordered with this option were shipped from Packard's East Grand Boulevard facility to the B&B factory where the installation was performed.

[4] The 1953 Chrysler Imperial was one of the first production cars in twelve years to offer modern automobile air conditioning as an option, following tentative experiments by Packard in 1940 and Cadillac in 1941.

As the highest capacity unit available at that time, the system was capable of quickly cooling the passenger compartment and also reducing humidity, dust, pollen, and tobacco smoke.

[11][12] 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 Nash models.

[15] Combining heating, cooling, and ventilating, the new air conditioning system for the Nash cars was called the "All-Weather Eye".

[15] With a single thermostatic control, the Nash passenger compartment air cooling option was "a good and remarkably inexpensive" system.

General Motors offered a front-mounted air conditioning system made by its Harrison Division on 1954 Pontiacs with a straight-eight engine.

[23] The unified alternative layout pioneered by Nash "became established practice and continues to form the basis of the modern and more sophisticated automatic climate control systems.

[25] 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.

[29] 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.

[32][33] Most are aftermarket relatively inexpensive accessories consisting of an external window-mounted metal cylinder without moving parts, but internal under the dashboard or center floor units with an electric fan are available.

[34][35] It was an early type of automobile air conditioner[36] and is not used in modern cars relying on refrigerative systems to cool the interior.

This refrigerant was the industry standard until the 1970s when scientists discovered that R-12 contained chlorine which depleted the ozone layer in the earth’s atmosphere.

In a thermal expansion valve air conditioning system, the condensed and pressurized liquid refrigerant is next routed through the receiver-drier, that is, a one-way desiccant and filter cartridge that both dehydrates the refrigerant and compressor lubricant oil mixture to remove any residual water content (which would become ice inside the expansion valve and therefore clog it) that the vacuum done before the charging process did not manage to remove from the system, and filters it to remove any solid particles carried by the mixture, in addition to acting as a storage vessel for any excess liquid refrigerant during low cooling demand periods, and then through the thermal expansion valve where it undergoes an abrupt reduction in pressure.

In such an air conditioning system, the accumulator also prevents the liquid refrigerant from reaching the compressor during low cooling demand periods.

Both control means can act (either directly or by means of a control unit fed by their data) upon the compressor's clutch engagement status or, in the case of a variable displacement compressor, its displacement; additionally, a secondary valve located on the suction side can throttle the refrigerant flow so that the evaporator's outlet pressure doesn't fall below a precise value during system operation.

The Standard 6032 of the Association of German Engineers (VDI) provides an overview of the hygienic maintenance of vehicle air conditioning systems according to the state of the art.

Regular cleaning of the air conditioning evaporator must therefore ensure that the biological colonization of the surface is interrupted and that the sometimes toxic decay products of bacteria (endotoxins) or metabolites of mold (mycotoxins) are safely removed from the lamella system.

The necessity of hygienic cleaning of ventilation systems in vehicles at regular intervals is not only logically understandable, but is also described by the technical guideline and standard VDI 6032 of the Association of German Engineers.

The pollen filter box must be cleaned professionally and the air conditioning system evaporator must be flushed hygienically and effectively with cleaners without fragrances (allergy triggers) every 24 months at the latest.

With a professional air conditioning system cleaning according to the current state of the art, mould, germs, bacteria and other odor-forming substances or deposits are literally washed away at the point of origin.

Since the method described has not yet become established in everyday workshop practice, the use of so-called "one click cans" is currently enjoying great popularity.

Only the combination of mechanical pressure flushing and a suitable cleaning agent directly on the evaporator leads to the desired result.

Factors such as wind resistance, aerodynamics, engine power, and weight must be considered, to find the true difference between using the air conditioning system and not using it, when estimating the actual fuel mileage.

A debate had emanated from the decision of the European Union to phase out the current high global warming refrigerant HFC-134a in car air conditioning from January 2011 onwards.

[51] To comply with the legislation carmakers have to decide on new refrigerants, as they typically need 3 to 4 years to develop and introduce a new car platform including the new air conditioning system.

All of the refrigerants which the EPA approved for motor vehicle use in place of CFC-12 (as of 28 September 2006) contain no more than 4% of total flammable hydrocarbons (butane, isobutane, and/or isopentane).

In September 2007, the German Association of the Automotive Industry (VDA) officially announced its decision to use CO2 as the refrigerant in next-generation air conditioning.

A working group at the European Automobile Manufacturers Association (ACEA) proposed drafting an industry-wide common position.