Man Explaining His Friends

How An Automotive A/C Works

Have you ever wondered how the air conditioning in your car works? Most of us basically know that an A/C cools down the temperatures in our cars when they get high. Do you know that an A/C also reduces the humidity or moisture content as well? Now you do. All air conditioners operate the same whether they are installed in a car or a building. This piece however, will focus more on how an automotive A/C works.

In order for an A/C to function properly, it operates in a number of principles which include condensation, evaporation, compression and expansion. A car’s air conditioner is designed with five main components that form the entire system and they include the compressor, receiver-dryer, condenser, expansion valve and the evaporator. There is a fluid that runs through the whole system known as a refrigerant which can condense at a high pressure and evaporate at a low pressure. Let’s take a look at these components individually to get a better understanding of how the whole system works.


The compressor does most of the work in an A/C system and it is considered the work horse. It is connected to the crankshaft of the engine that is powered by a drive belt. When you turn on the air conditioner, the compressor is used to pump the refrigerant vapor into the condenser under high pressures.


Once in the condenser, the high pressure refrigerant vapor is changed into a liquid state. The condenser is the device used to realize this change. This device looks much like a radiator itself and is mounted on the front part of the engine’s radiator. When the high pressure refrigerant changes into liquid form, it generates a great deal of heat. The heat gets removed from the condenser by flowing air inside the condenser to the outside.


The receiver-dryer receives the liquid refrigerant from the condenser. The receiver acts a small reservoir where it holds the liquid refrigerant and any moisture that may have leaked into the refrigerant gets removed at this stage.  A small amount of moisture can cause havoc to the whole system since ice crystals can form which cause mechanical damage and blockages.

Expansion Valve

The expansion valve then receives the pressurized refrigerant from the receiver. The expansion valve is used to remove pressure from the refrigerant to allow it to expand into vapor.


Just like the compressor, the evaporator resembles like a car radiator. It consists of fins and tubes which are mounted inside the passenger compartment above the footwell behind the fascia. The refrigerant passes through the evaporator and absorbs heat from the air. A blower fan placed inside the compartment on the passenger side pushes air over the evaporator’s outside which lets cold air circulate inside the car. Any moisture inside the car is condensed and then collected and drained away.