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Development of climate control systems in modern

humanity has come in such a short time regarding the development of climate control systems in modern vehicles. A technician should understand what functions an HVAC system is intended to perform and how the system accomplishes these tasks. Next the technician will be introduced to the components that make up a modern HVAC system and the tools required to maintain these ever-evolving systems.

  • SYSTEM OVERVIEW

In this chapter, the technician will first be given a brief history of the modern HVAC system. The technician will then be introduced to the purpose of the heating, ventilation, and air-conditioning system and be given a brief description of the components making up modern HVAC systems. These components will be discussed in detail in later chapters. This chapter will
finish with an introduction to some of the specialty tools used by technicians in the HVAC field.

  • HISTORY OF AIR CONDITIONING

People who lived as far back as the ancient pharaohs of Egypt were probably the first to actively try to control the temperature of their environment. Evidence shows that each night, thousands of workers were used to disassemble the inner walls of the pharaoh’s palace, and the thousand-pound blocks were carried into the desert, where they were left to cool during the night. The next morning they were taken back to the pharaoh’s palace and the inner walls were reassembled. This extreme amount of work allowed the palace to remain a relatively cool 808F (278C) when the temperatures outside the palace were as high as 120–1308F (49–548C).



In 1884, the Englishman William Whiteley placed blocks of ice in a tray under a horse carriage and used a fan attached to a wheel to force air inside. Later, a bucket of ice in front of a floor vent became the automotive equivalent. Railway passenger cars also used to have large blocks of ice loaded into containers built underneath the passenger compartment; a fan was used to blow air
over the ice and circulate cool air through the rail car. Automobiles were not very comfortable in the early years because the cabs were open. Passengers had to wear many layers of clothing in the winter, and in the summer the only ventilation was what could be brought in through the windows or open top of a vehicle that could cruise at a speed of 15 mph. Car companies then began closing up the cabins on cars; this required a change in temperature control systems. First, vents were put in the floors of cars, but this brought in more dirt and dust than it did cool air. In early attempts to cool the air, drivers placed buckets of water on the floor of their cars, thinking that air flowing over the surface of the water would cool the occupant compartment of the vehicle. Evaporative cooling systems soon followed. In 1939, Packard produced the first passenger cars using refrigeration components. The huge evaporator was mounted in the trunk, leaving little room for luggage, and the
only way to shut the evaporator off was to stop, raise the hood, and remove the drive belt from the compressor. Cadillac followed suit in 1941 with an air-conditioned car, and in 1954, Delphi Harrison Thermal Systems engineered an air-conditioning system that located all the major components of the air-conditioning system under the car’s hood (Figure 1-1). TODAY’S AIR-CONDITIONING
SYSTEMS Thanks to recent advances in modern technology, today’s vehicles are extremely comfortable no matter what the weather is like outside the vehicle. Innovations such as computerized automatic temperature control (which allows you to set the desired temperature and have the system adjust automatically) and improvements to overall durability, have added complexity to today’s air-conditioning systems. When today’s truck drivers travel through regions of differing climates
throughout the United States and Canada, they can enjoy the same comfort levels that they are accustomed to at home. With the simple slide of a lever or

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