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Everything to Know About Aircon Regas And Maintenance

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Recharging your car's AC is necessary even outside of summer. Here's everything you should know about aircon regas, from time to procedure to results. Air conditioning (also known as AC or aircon) is a valuable feature in any car.

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Air conditioning (also known as AC or aircon) is a valuable feature in any car. During summer, it keeps the driving experience pleasant and reduces the wear and tear that heat can place on the interior of your vehicle. During winter, it's a helpful way to dehumidify a car, clear fogged up windows, and prevent a damaging jolt to the vehicle's system when you begin heating it up after cold temperatures.

Unfortunately, a car's air conditioning system isn't self-sufficient, like a kitchen's refrigerator. It needs to be recharged or regassed once a year, and sometimes more frequently.

What does this process entail? How much does it cost, and how does it actually work? To better understand this service before you request it of your mechanic, here's a complete guide to a car's aircon regas:

What's Included In Aircon Maintenance For A Car?

When your vehicle's AC is serviced, there are moving parts, filters, fans, and coolant gas that all need to be checked, cleaned, and topped up. If this maintenance is performed regularly, a technician will only need to:

  • Clean the system
  • Clean out air filters (especially if there is debris or mould growing in them, as is common in damp climates)
  • Refill lost refrigerant
  • Empty and replace the old refrigerant if needed

However, leaving the systems unused for extended periods of time, or using them without regular checkups, can lead to rusting, broken seals, or damaged hoses. This will call for repairs and replacement parts, which may drive up the maintenance fee.

To lower the cost of maintenance, you can also perform a simple checklist by yourself:

  • Test run the AC regularly, even if you don't need it at that moment
  • Use it in the winter to dehumidify your car
  • Change the cabin filter every few months

How Does Air Con Work And Why Does It Run Out?

The short answer : In order to cool down warm air, a refrigerant gas is needed. Over time, the refrigerant changes state between gas and liquid so often that parts of it are lost through the system.

As such, there's less available to help cool the warm air, and the aircon system ceases to function. Refilling this gas or replacing the old, used-up refrigerant will allow it to start working again.

The long answer : While it may seem counterintuitive, the entire process of cooling air starts with compressing a gas to a high temperature. This change in state is then used to create dramatic changes in the surrounding air temperatures.

These altered temperatures are then blown out as cool air into your cabin. This removes humidity and results in a far more pleasant climate within the vehicle.

All that is made possible with three components from the aircon system, namely the:

  • Compressor
  • Condenser
  • Evaporator

Compressor Starts The Process

When the aircon is turned on, the gas in the system starts being compressed by the compressor, as the name implies. When a gas is compressed (pressurised), its temperature will rise.

The compressor's job is to pressurise the refrigerant gas to around 85°C. At this point, the very hot, high-pressure gas is sent to the condenser.

Condenser Heats Up The Refrigerant

The condenser is similar to a household radiator (in fact, it's sometimes called "the radiator" on a car). The high-pressure, high-temperature gas passes through the coils in the condenser, and the outside air that passes over the condenser coils then cools the gas down to around 55°C.

Importantly, it's kept at the same high pressure – and this has the effect of turning the gas into a liquid. From here, a "drier" component in the condenser works to remove water from the system. This avoids any crystallisation that might block or damage the components.

At this point, the high-pressure, somewhat cooler liquid is then sent to the evaporator.

Evaporator Cools Things Down

At the beginning of the evaporator is an "expansion valve." Simply put, this behaves like the nozzle of a spray can. By creating a very small hole - through which the high-pressure liquid can pass quickly into a much lower pressure area - the liquid cools suddenly, all while turning back into a gas.

This gas cools to a temperature of around 0°C (which is not the freezing point for gas) and this now-cool gas passes through the evaporator. As it travels through the evaporator coils, a blower takes air from inside the vehicle and blows it over the cold coils and then into the cabin.

The low pressure gas then goes back into the compressor to start the process again. Like magic, you have cool air to make your summer drive bearable.

This is almost entirely a closed-loop system – but the drier has the effect of removing parts of refrigerant that didn't turn into a liquid properly, as well as removing any accumulated water. So, over time, the system runs out of refrigerant and needs to be topped up.

Why Should You Invest In An Aircon Regas?

Regassing your aircon is necessary for the air conditioning system to work over time. As such, if you want continued AC and cooler temperatures in your car, it's necessary to get this maintenance performed.

There are perks aside from this, however. Here are bonus reasons to recharge or regas your AC:

Fuel Efficiency

Recharging your aircon increases fuel efficiency, allowing you to save money in the long-run. Why?

If your AC refrigerant is low, the aircon system struggles to cool the air. It then works harder to try and produce cold air, which demands extra fuel. By having your system regassed and working in peak condition, it will only use the bare minimum petrol.


If you don't want to pay for expensive aircon parts and repairs later on, then a regassing schedule is necessary. The refrigerant used in your air con system is extremely cold and has the added benefit of cooling down the aircon compressor. Without refrigerant, or if it runs too low, the compressor will get dangerously hot and fail.

That's paired with dirty air filters that can get clogged (or blow bacteria and mould), seals that crack over time, and hoses that get worn out. A mechanic will check over the entire system while regassing the aircon, and this allows routine maintenance to be performed long before replacements as needed.

Winter Uses

Air conditioning has its uses even on cold winter days. If you are struggling to demist your windscreen, use the aircon to produce dry air to rapidly clear your view. This also ensures the system doesn't seize up when the temperature do become warm.

How Often Should You Regas Your Car?

This depends on your particular car model, but the rule of thumb is to regas your car every 2 years – ideally as part of a general service. Unlike most car parts, this isn't related directly to mileage or how often your aircon is used.

A regas and air con service usually takes around 45 minutes – but it depends on the age and condition of the car, as well as the aircon system itself. It's operational almost immediately after a recharge, so you don't have to wait for anything to settle in before using it.

Is An Air Con Regas Part Of A Major Service Or MOT?

No, your annual MOT ensures the vehicle is safe to drive as per strict DVSA guidelines. Since air conditioning is considered a "nice-to-have" feature, it's not critical to the safe running of the vehicle. As such, your MOT tester will not fail you based on its condition. Some testers may not even check if your aircon is working.

Similarly, air con is not included in the standard service schedule set out by your vehicle manufacturer. Regular servicing will help keep your car running for longer in a safe and reliable condition, and includes some replacement parts like the oil and air filters. You will need to check in with a local auto centre to have your AC checked specifically.

Where Can I Get My Air Con Recharged?

At Autofusion, we offer a complete air conditioning recharge service, alongside a Recharge or No Charge guarantee, should we find a leak in your aircon system and the recharge cannot be completed.

If we can't improve the coolest vent temperature in your vehicle by more than 10% when measured in degrees Celsius, then we will happily refund you the price of your recharge. Our centre staff can also help to diagnose problems with your aircon system, should your system not hold its charge.