Air conditioning
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 US inventor Willis Carrier. The introduction of residential air conditioning in the 1920s helped enable the great migration to the Sun Belt in the United States.
Nash Motors
Using its Kelvinator refrigeration experience, the automobile industry's first single-unit heating and air conditioning system was introduced by Nash in 1954. This was a compact, affordable system for the mass market with controls on the dash and an electric clutch. Entirely incorporated within the engine bay, the combined heating and cooling system had cold air for passengers enter through dash-mounted vents. Competing systems used a separate heating system and an engine-mounted compressor with an Evaporator in the car's trunk to deliver cold air through the rear package shelf and overhead vents. 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."