How Does AC Refrigerant Work? Why We Need to Recharge AC Refrigerant?

As the weather gets hotter, the first thing you want to do when you enter the cabin of your car is to turn on the air conditioner. The air conditioner absorbs the warm air inside the car and cools it until it reaches the cooler temperature you set.

All AC systems have refrigerant in them, which is why when the cooling capacity drops the first thing a repairman will do is check for refrigerant leaks. So how does AC refrigerant work? Read on to learn how refrigerant works in an air conditioning system, and to give you an idea of what parts to look for when it comes to maintenance.


What is a AC Refrigerant?

A compound that easily changes from a liquid to a vapor (and can also condense from a vapor back to a liquid in a constant cycle). Some of the more commonly used air conditioning refrigerants include
Chlorofluorocarbons (CFCs), including R12. Which were discontinued in 1994 because of the greenhouse effect caused by damage to the ozone layer.
Hydrochlorofluorocarbons (HCFCs), including R22. Although less damaging to the ozone layer than R12, were mandated by the EPA under the Clean Air Act of 2010.
Hydrofluorocarbons (HFCs), including R134a. HFCs are safer for the environment because they do not contain chlorine in the mixture.  R134a is also used in most cars today.


How does AC refrigerant work in AC system?

Compression of AC refrigerant

When the refrigerant is pushed into the compressor, the compressor pushes the gas molecules together. As the pressure rises, the temperature of the refrigerant rises as well. The compressor keeps the refrigerant moving in a continuous cycle through the air conditioning system.


The pressurized refrigerant is sent to the condenser, where hot air is usually found blowing out of the working condenser. The condenser fan blows air through the condenser (in an air-cooled system) to remove unwanted energy. As the air is blown through the tubes, it removes the heat from the refrigerant.


Every air conditioning system has a metering device to keep the refrigerant moving at a constant rate and to measure whether the system is continuing to cool or just maintaining the current temperature.


The refrigerant eventually reaches the evaporator, where a fan blows warm air from the vehicle across the evaporator coil. When the temperature in the room is higher than the temperature of the refrigerant, then the refrigerant will absorb heat, causing the surrounding temperature to drop. When the fan keeps running the cold air will be pushed into the car.

Finally, the refrigerant that has absorbed heat becomes a warm low pressure gas and is then sent to the compressor, which continuously cycles the above process to cool down the temperature. This is the circulation of refrigerant in an air conditioning system.

open car ac system
This is why when the cooling capacity of the air conditioning system decreases, you should first think if there is a refrigerant leak. Then determine what refrigerant the air conditioning system is using according to your car's guidelines and finally fill the system with refrigerant.

Remember, when you choose to recharge the A/C system yourself, choose a high quality manifold gauge kit or you may have a leak while it is working. In other articles we have described in detail how you should choose a high quality manifold gauge and how to use these kits.