Air conditioning – how does it work and how much does it cost?

Temperatures are on the rise and June 2023, according to the Met Office, was the UK’s hottest on record for the UK. This means that many of us are more likely to get in the car and turn on the air conditioning to make our journeys a bit more comfortable.

But how does air conditioning work and how do you keep your system it in tip-top condition? If it currently isn’t very effective, how much does it cost to get it fixed? Read on to find out more!

How air conditioning works

There are a number of parts to an air conditioning system including a compressor, condenser, receive/dryer, expansion valve and evaporator.

Air conditioning in your car works by using a compressor to compress refrigerant gas, which as its compressed gets up to around 80 - 85°C. This hot, high-pressure gas is then passed to a condenser, and air from outside of the vehicle passes around this gas within coils in the condenser which reduces its temperature very quickly, and as a result turns the gas into a liquid.

This high-pressure liquid then moves to a receiver/dyer which helps to filter out any debris and impurities that the liquid may have picked up while travelling through the condenser.

The liquid is then passed through an expansion valve to become low-pressure, and moves on to the evaporator which is located in the interior of the vehicle. As the name suggests, this part of the process evaporates the now low-pressure liquid very quickly (turning it back into a gas), and during this cooling process, air is blown over the cold evaporator coils as it enters inside the vehicle, which is the cold air that we feel. The cooled, low-pressure gas then re-enters the compressor where the process repeats.

Air Conditioning - how it works and how much it costs

How much fuel does air conditioning use?

Using your air conditioning requires power from your engine, and it’s estimated that it uses 2-4hp, depending on the outside temperature. So using your air conditioning, because of the additional strain it puts on the engine to create the process outlined above, does eat a little into your fuel. How much fuel is used varies depending on how modern your vehicle is and how efficient the air conditioning process is, but a number of sources suggest using air con can increase fuel usage by up to 10%.

It’s also estimated that vehicles lose about 10% of the refrigerant gas each year just through natural leakage in the system, so the less gas available means the harder the air conditioning (and ultimately the engine) has to work to cool the inside of your car.

It’s recommended that your air con is regularly serviced by expert technicians, such as at our Bosch Car Service centre in Braintree, Essex, which will help ensure your system runs as efficiently as possible, saving you from using unnecessary fuel.

Using air conditioning all year round

Many of us associate putting the air conditioning on during the spring/summer months to cool the inside of the vehicle, and most then won’t switch the air con back on until the same time the following year. However, it’s recommended that you actually use your air conditioning at regular intervals throughout the year to keep your system in good shape.

One of the reasons is to help reduce the forming of bacteria. Due to the cooling of the gas into a liquid, any residual condensation which is left in the system can become stagnant and form bacteria - which will then be circulated around vehicle the next time the air con is turned on. This can be helped by using your air conditioning regularly throughout the year so there’s less opportunity for liquid to become stagnant. If there’s a musty smell coming from your system, it’s a good idea to rectify this with an Air Conditioning Refresh from Quest (see details below).

The second reason is that it’s also possible due to inaction over a long period of time, that the rubber seals which help connect the various parts of the air conditioning system can become hard and brittle and ultimately crack, which is often why it starts to leak gas. You’ll find PAG (Polyalkylene Glycol) oil in your air con system and it’s used to lubricate the moving parts in the compressor, but it also keeps the rubber seals and connections supple. When the air con is turned on, the oil is circulated around the parts to keep them lubricated, but when it’s off, this oil slowly evaporates and then the seals start to dry out.

So turning on your air conditioning regularly throughout the year is really beneficial in keeping your system working as it should.

Maintaining your air conditioning

At Quest Motor Group, we can help with all of your air conditioning needs. To start with, we recommend that every year an Air Conditioning Refresh (£25) is booked, which will kill bacteria residing in your system, and replace any obnoxious smells with a fresh scent of your choice.

Every two years, we recommend a full Air Conditioning Service (£139) is booked. We’ll replace the refrigerant gas so you’re fully topped up again (which means your engine won't need to work so hard to cool you down) and ensure it’s charged as per your manufacturer’s specification, plus we’ll also check all components and pipes to ensure there are no leaks in your system.

By routinely using the above services, you can be confident that your air conditioning system is clean and in tip-top condition, ready to be turned on whenever you need to use it (and try to remember to use it all year round!).

Book an Air Conditioning Refresh or Service today