How Does Car Air Conditioning Work

Most people do not really care about how their air conditioning works as they just want it to work. However, it’s always good to know how your car’s air-conditioning works in your car as it could be useful to know when it needs repairing or servicing. If you are the type of person who has always wondered how it works, carry on reading and we will explain exactly how does car air conditioning work. Bonair is the expert when it comes to automobile airconditioning units.

How Does Car AC Work

The refrigerant in an automobile’s air-conditioning system is changed between a liquid and a gaseous state by the car’s air-conditioning system. The refrigerant changes state, absorbing heat and humidity from the car while at the same time allowing the system to release cool, dry air, which gets the temperature in your car down so you won’t be sweating for your journey.

The air conditioning system works on controlling the pressure as well as the temperature in order for the refrigerant to change from a liquid state to a gas state.

Car Aircon Refrigerants

Previously, vehicle air-conditioning systems used to use R-12 as the refrigerant. R-12 (aka Freon) is a very effective CFC-based (chlorofluorocarbon) refrigerant that is not flammable and not poisonous to humans. However, scientists in 1980 found that this type of refrigerant was causing damage to the ozone layer around the Earth.

This caused the manufacturers to change over to R-134a around the mid-1990s. This refrigerant is HFC-based (hydrofluorocarbon) which means it has no ozone-destroying properties unlike R-12. Nowadays, the go-to refrigerant is r1234yf. This is because it produces very few greenhouse gases and in Europe, it is required on all vehicles.

What Parts Go Into An AC System.

Car air conditioning units are only made up of 5 components.


The compressor is the power unit of the system which keeps the low-pressure side and the high-pressure side separate from each other. It works by taking the low-pressure gas and compressing it into a high-pressure gas. The compressor is mounted to the serpentine belt at the front of the vehicle’s engine.


Whilst the pressure remains high, the compressor’s main job is to reduce the temperature of the refrigerant. As it cools, the refrigerant turns from a gas state into a liquid state. Then, like the engine radiator, it uses forced air to transfer the heat. The compressor is located at the front of the vehicle behind the grill.


The dryer’s job is to remove water from the refrigerant using a drying agent also known as a desiccant. The dryer has filtering properties to keep the air clean and is located on the high-pressure side of the AC system in between the condenser and metering device.

Metering Device

The metering device is usually an expansion valve or a fixed orifice tube. The job of the metering device is to lower the pressure of the refrigerant which will dramatically drop the temperature of the refrigerant. After leaving the metering device, the refrigerant is still in a liquid form. This component is located on the high-pressure side of the AC unit between the firewall and the dryer components.


In the evaporator, the refrigerant changes back to a gaseous state which causes the cooling effect. The air in the car is cooled and dried as it blows out across the evaporator. This is the only part which is located in the passenger part of the car behind the dashboard.

How Does Car AC Use Fuel

It is a known fact that using your car’s AC unit uses some of your fuel to work. The reason for this is that the compressor requires power to run the AC unit. Therefore, whenever the system is running, it uses a small bit of fuel to create the energy needed. Studies have found it can increase fuel usage anywhere from 10%-20%. As well as this, you are more likely to notice the effects on smaller journeys.

Car AC Not Working?

If you have noticed your car’s air conditioning unit has stopped working, it could be to do with any of the components. There are many signs that your car’s aircon needs repairing. Get in touch with Bonair today and visit our shop in Essex for car aircon re-gas, repairs & Servicing.


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