Car air conditioning - all you need to know

All you need to know about car air conditioning

Is there anything worse than sitting in a stuffy car when your air conditioning is broken? Or have you ever wondered how you would demist your windows on colder mornings without it? Believe it or not, there are a few reasons why your car's conditioning system requires just as much care and attention as the rest of the vehicle.

How does air conditioning work in a car?

Before we get started, it's important to know that a car's air conditioning system is made up of five key parts; the compressor, which contains the refrigerant, condenser, evaporator, receiver/dryer and thermal expansion tube.

When the car's air conditioning system is engaged, the refrigerant, or the gas, travels to the condenser. The atmosphere's fresh air passes over the condenser and this causes the gas to drop in temperature and turn into a liquid.

In turn, the liquid goes through a receiver, removing any impurities, before reaching a thermal expansion valve.Your valve then allows you to control the temperature by adjusting the flow of the liquid. The liquid is turned into a vapour as it passes through the evaporation coils, which is then blown into the cabin as cool air.

As this point, the refrigerant has turned into a gas again and goes back to the compressor ready for the process to start all over again.

Why is air conditioning in a car important?

An efficient air conditioning system can help you save money. If the air conditioning refrigerant falls to a lower level, the air conditioning system must work harder to produce colder air, which is done by using fuel.

Making sure your air conditioning system is up to scratch, and doesn't contain any build-up of bacteria, can also help you avoid allergic reactions and sore throats.

Of course, when the weather is warmer, and you need a blast of fresh air, a well-maintained system will help you cool down and keep comfortable while driving.

Why isn't my air conditioning working?

Like a car's oil or washer fluid, a car's air con system uses a compressor filled with refrigerant to cool down the air. This system will need regular top-ups to keep it working efficiently.

If you don't have enough refrigerant, the system allows air and moisture into the compressor shaft. This may cause the system's seals to fail, and you may encounter leaks or even eroded pipework.

How often should car air conditioning be serviced?

A car's air conditioning system should be regassed depending on manufacturer guidance for the specific make and model.

General guidance suggests that it should be regassed every two to three years. This should be done during the car's general service.

The servicing of an air conditioning system differs to servicing other parts in your car. This is because it doesn't directly relate to the vehicle's mileage or how often you’ve used your air con.

Can I recharge my air conditioning at home by myself?

The process of recharging your air conditioning system is fairly simple if done correctly. However, you'll need to have the right type of gas for your car as well as the correct tools. Gas types differ from vehicle to vehicle depending on age and model. If in doubt, you should contact the Service department at Arnold Clark.

Car air conditioning myths

Using the air conditioning ruins your fuel economy

While using your air conditioning system will increase fuel consumption in internal combustion engine cars and battery use in electric vehicles, the consumption penalty isn’t as harsh as people may think. This is because the car uses a compressor to run the system which requires energy from an engine or motor.

According to the Energy Trust, drivers can expect to see up to a 5% drop in fuel efficiency when driving with the air conditioning switched on, but other factors, such as under-inflated tyres, driving at higher speeds, a packed boot, or a bike rack/roof box attached to the car, can similarly impact fuel efficiency.

You should not have the air conditioning on when starting your car

With modern ignition systems, stop-start technology and electric vehicles, there is no cause for concern when starting a car with the air conditioning switched on.

Air conditioning is a luxury and not essential

As stated above, most cars now come with climate control as standard.

How to regas air conditioning – the process

1. Step one

   Check the levels to understand if there is any refrigerant left in the air conditioning system.

   The charging hose that is fitted next to the low-pressure port near the accumulator will show the level of refrigerant.

   If the system is completely discharged, there may be a leak. If this is the case, recharging will not fix the issue. In fact, it's actually illegal to knowingly regas a car that will leak refrigerant.

2. Step two

   It's no surprise to learn that a leak will affect the car’s air conditioning systems and, as said previously, recharging with a significant leak will not help fix it.

   The leak can be found by using a refrigerant sniffer. If the system has air conditioning UV dye in it, a UV light can be used to check all around the system to identify a yellow glow, which will show the leak.

   Another top tip, more often than not, the condenser is at the front of the car, so it's best checking there first.

3. Step three

   Next, you'll want to open the valve on the tapping fitting. Tap your refrigerant can by pinning it into the valve body. If this is not done properly, it will lead to tap puncturing which will release the refrigerant before it is properly sealed.

4. Step four

   The refrigerant can should be securely and safely attached to the tapping valve.

   Once the valve is opened, the refrigerant is released, which should take between two to five minutes.

   The pressure should be measured with a gauge to ensure the system is not overcharged.

5. Step five

   As the refrigerant fills the valve, the brass fitting that is connected to the hose should be slowly and carefully loosened.

   Care should be taken as contact of refrigerant on bare skin will result in the freezing of skin tissue. When the refrigerant has been released, the hose should be tightened.

6. Step six

   The low-pressure charging port should indicate that there is no further leaking. This is usually located on the larger tube near the accumulator.

7. Step seven

   Start the air conditioning system to check if the compressor is working correctly.

8. Step eight

   At this point, after refrigerant is recharged, check if the air produced by the system is cool enough.

   If it is not, this could mean that either the refrigerant was not sufficient or there is another issue. If this is the case our technicians can identify the problem and resolve it.

Your questions answered

How long does it take to recharge an air conditioning system?

To recharge or regas a car's air conditioning system during a service should only take around 45 minutes. However, this may depend on the condition of the air con system, or the age of the vehicle.

Once the air con has been recharged, it should be ready to use straight away.

Is an air con regas part of a major service or MOT?

You'll find that most cars now come with climate control as standard, which is perfect for driving in comfort all-year round. However, to make sure this is the case, you'll need to make sure your air conditioning is in perfect shape.

Since air conditioning is considered as an added feature, it isn't critical to the safe running of the vehicle, meaning it won't be checked during an MOT.

However, if you follow the guidance of your service plan, most manufacturers recommend that your air conditioning is serviced every two years.

Where can I get my air conditioning regassed?

We are always here to help. Whether you need regular maintenance or a full service for your air conditioning, Arnold Clark has you covered. All Arnold Clark branches offer free air conditioning checks and a full service or regas.