All types of air cooling systems from home to auto air conditioning units all operate on the same principles and have the same basic parts. This makes understanding how your system works just a bit easier, especially if you imagine your much larger system in your house. There are two major parts to any air conditioning unit, these are the condenser and the evaporator core.
The compressor is the pump part of the system that moves the cooling solution, Freon, through the auto air conditioning system. While moving through the system the Freon, which is a gas and liquid, is forced through different sized metal and rubber hoses and tubes, through what is known as an expansion valve. This constant pressure and condensing and expanding of the Freon makes it get very cold within the metal and rubber hoses. As the Freon moves into the dash area of the vehicle it is moved into a metal tube system that is called the evaporator core. This system is similar in function to a radiator, however the very cold Freon within the interior of the metal tubes in the evaporator core cools the air that the air conditioner fan blows from the back of the dash to the front. This cooled air is then blown into the passenger area of the vehicle through the vents located in the dash.
The control on the dash that the driver or passenger can adjust actually doesn’t control the temperature of the evaporator core, rather it controls how much air is blown across the core. The greater the amount of air the more cold air that is pushed into the vehicle’s cab or passenger area. More sophisticated systems have a thermostat that automatically adjusts the fan and controls the temperature of the passenger compartment. As the temperature rises, the thermostat sends a signal to the fan to speed up and produce more cold air, lowering the temperature.
Auto air conditioning systems also remove heat from the vehicle with the Freon that is returning from the evaporator core to the condenser. This is done at the front of the engine, usually close to the radiator. The warmed Freon is moved to the condenser, which is like the evaporator core but instead of allowing the cold Freon to cool the air, it allows the hot Freon to release the heat to metal fins, then a fan blows this heat away from the engine. In this way the auto air conditioning system works as both a cooling and a heat removal system as the Freon circulates through the hoses and metal condenser.