AIR CONDITIONING

Air conditioning was used on a few passenger buses as far back as 1938. Then in 1940 Packard introduced the first air-conditioned car. It is now the most popular accessory on all cars manufactured in the United States. In 1962 only 11 percent of American cars were factory-equipped with air conditioners. The percentage of new-model, factory-equipped air-conditioned cars rose each year to 80 percent in 1970 and 90 percent in 1978.

As described in Chapter 1, air conditioning removes heat from the passenger compartment and delivers it into the atmosphere. Air con-ditioning simultaneously cleans, cools, circulates, and removes moisture from the air within the passenger compartment. Air conditioning and refrigeration are basically the same process. Considerable training and practice are required to service the components of an air-conditioning system. When one part needs to be serviced or replaced, the system must be drained of refrigerant. Then, after the part is reinstalled, the system must be cleaned, dried, and a vacuum created. This is accomplished with an evacuator or a vacuum pump. Finally, the system is charged with a refrigerant, R-12.

Training in air conditioning and in the use of special equipment, particularly the manifold gauge set, is needed to accurately diagnose some malfunctions in the system and to recharge it. However, in this chapter you will learn how to diagnose some of the malfunctions not requiring the use of a manifold gauge set, and, when necessary, how to add refrigerant to the system. A small amount of refrigerant seepage may occur when the air conditioning is not used for long periods of time, such as in winter. This refrigerant can be replaced without evacuating the system by using a one-pound can of refrigerant, R-12, and a special air-conditioning service hose and can adapter. Before doing any work on this system, you should check the air-conditioning compressor belt for tension.