How do my car’s air conditioning and heating systems work?
We take advantage of the fact that we can stay warm in our cars during Reading, PA winters and cool during Reading, PA summers, but our vehicles’ air conditioning and heating systems are fairly complex. To heat up your car, hot engine coolant is circulated through a small radiator, which is often called a heater core. There is a fan in front of the heater core to blow cool air to blow cold outside air over the fins. As this air travels through the heater core, it heats up and this is the warm air that blows out of your heater vents.
Your vehicle’s air conditioning system includes the condenser, compressor, expansion valve and evaporator. Refrigerant or coolant is compressed in the compressor and turns into a hot gas. This hot gas is cooled into a liquid state in the condenser, then travels to the expansion valve. In the expansion valve, the refrigerant turns back into a gas and rapidly cools in the evaporator. A fan blows over the evaporator and cools the air that blows out of your vents. If any parts of your vehicle’s heating or air conditioning systems are damaged, it can effect the entire system.
The Problem with R12
In order for refrigerant to work effectively, the liquid needs to have a low boiling point and should be a gaseous state at room temperature and easily pressurized as a liquid so it can boil at room temperature and then cool in the evaporator. In the early 1930s, a refrigerant called chlorofluorocarbon (CFC) was developed, and was given the name R12 or Freon. Although R12 met all the requirements for a refrigerant as stated earlier, it was found to be significantly reducing the Earth’s ozone layer. Starting in 1987, the use of R12 began to be phased out and were completely gone by 1994.
Automotive manufacturers started using tetrafluoroethane, or R134a (which also went by the name Freon), a refrigerant that does not have the ozone-destroying properties of R12. However, with this transition there came a lubricant issue. Air conditioning compressors require oil because they are constantly moving. The oil has to dissolve into the refrigerant, and therefore must be compatible with the refrigerant. Because of this, R134a manufacturers began selling Polyalkylene Glycol, or PAG Oil. Today, R134a is used in many vehicles’ air conditioning system, including in Ford, Chevy, and Chrysler vehicles.