Air-con regas - what you need to know

By: Lisa Harper

The weather may have turned a little wetter in the past week or so, but it has still been pretty hot, so chances are you will still be switching on the air-con on most of your car journeys. The blast of cold air in your car is a welcome retreat given the higher temperatures we've been enjoying, so when the air-con fails, it can disrupt the comfort of your journey. 

However, more often than not, poorly working air-con simply needs re-gassing (also known as re-charging), but what exactly is this and what does it entail? We explore everything you need to know about your car's air-conditioning.

Air-con in action

The air-con system in your car is made up of three main parts; a compressor, a condenser and an evaporator. These three parts work together moving the refrigerant through a high and low-pressure closed-loop system in which the refrigerant changes from a gas to liquid and then back to gas again, cooling your car in the process.

1. When switched on, the air-con system pumps refrigerant vapour from the compressor to the condenser. The refrigerant leaves the compressor as a high-pressure, high-temperature vapour. 

2. In the condenser, the heat is removed which turns the vapour into a high-pressure liquid.

3. The liquid refrigerant moves to a receiver-drier where moisture is removed from the liquid refrigerant.

4. The refrigerant flows from the receiver-drier to an expansion valve. In the expansion valve, the pressure is removed from the liquid refrigerant turning it into a low-pressure liquid.

5. As the cold low-pressure refrigerant is passed into the evaporator, it vaporises as it absorbs heat from the air in the passenger compartment. The blower fan inside the passenger compartment pushes air over the outside of the evaporator and cold air is circulated inside the car.

6. The refrigerant is returned to the compressor as a low-pressure vapour to start another cycle. 

So why does the air-con refrigerant get low?

Technically air-con refrigerant doesn’t get used up, however, it can get low if there are any leaks in the system. These can be small natural leaks that occur due to the materials used throughout the air-con system or can be larger leaks due to a fault somewhere in the system. 

How do you know when your car air-con requires a re-gas?

The first sign that your car needs an air-con recharge is that the air blowing from the vents is not as cold as it once was. Another sign can be that switching the air-con on has little effect.

You may also notice that your fuel efficiency drops and you are having to make more frequent stops at the fuel station. This is because when the air-con refrigerant is low, the air-con system must work harder to cool the air, and uses more fuel. 

What happens when you take your car for an air-con regas?

An air-con regas is a simple procedure; the old refrigerant gas is removed from the air-conditioning system and replaced with new refrigerant gas. The process should only take around one hour, so is something you can wait to have done rather than having to leave the car at the garage.

How often does your car need an air-con regas?

Most manufacturers recommend you service your car’s air-conditioning every couple of years. It is easy to forget about getting your air-con regassed, especially when the weather is less favourable. However, even in winter, your air-con can be crucial as it is much quicker at de-misting your windscreen than normal climate control.

Why bother getting your air-con regassed?

- Correctly working air-con can make a hot and stuffy car more bearable.

- Demisting a windscreen is quicker when the air-con is working.

- The car will run more efficiently and will use less fuel when the air-con is operating correctly.

- Air-con refrigerant helps to cool down the air-con compressor protecting it from overheating.

How to best maintain your air-con?

To keep your car’s air-con in the best condition, you should use it all-year-round, rather than just in the summer. Not only is your air-con an extremely quick way to de-mist your windscreen in wintery conditions, but regularly switching on your air-con can help to ensure that it doesn’t seize up.

You should also make sure you change the cabin filter regularly and should book your car in for an anti-bacterial clean if you notice a musty smell for the vents.


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