Air Con recharge: how it is recharged and whether it is worth it

Car not cool enough anymore? Keep calm and recharge your air conditioning unit.

Of the many luxuries offered by modern cars, air conditioning is perhaps the one that makes driving the most comfortable. Gone are hour long journeys in a stuffy, boiling car in summer and you can stay cool and in comfort on every little trip to the shops. What happens, though, when your AC stops blowing out cold air and why does this happen? If your AC is blowing out warm air or only works intermittently, you might have run low on the substance that gives your car this magic cold air capability. An AC recharge can bring back cold air when you need it most on hot days.

What is air conditioning recharge?

The air conditioning in your car works thanks to a compressor, refrigerant, and an evaporator. Air conditioners chill indoor air by forcing special chemical compounds to evaporate and condense over and over again in a closed system of coils. These compounds are refrigerants that have properties enabling them to change chemical state at relatively low temperatures. Air conditioners also contain fans that push the air in your cabin over these cold, refrigerant-filled coils.

When hot air flows over the cold, low-pressure evaporator coils, the refrigerant inside them absorbs the heat and changes from a liquid to a gaseous state. To make sure that it keeps cooling efficiently, the compressor puts the refrigerant gas under high pressure which converts it back to a liquid again. All the extra heat created by compressing the gas is then taken out of the system with the help of a second set of coils called condenser coils and a second fan. As the refrigerant gas cools, it changes back to a liquid and the process starts all over again. It is like an endless, elegant cycle designed to keep you cool: Liquid refrigerant is converted to a gas as it absorbs heat, then it is compressed and back to a liquid again so that it is ready to absorb the heat from the air in the car interior. Magic…or science to be precise. 

Car air conditioning recharge is the process of removing the old refrigerant gas from your air conditioning system and replacing it with new refrigerant, so your air con can run cold again. When considering where to get air conditioning recharge service, your garage should be your first point of call, but it might also be possible to do an air con regas yourself.

Why do air conditioners need to be recharged?

In theory, the refrigerant shouldn’t need to be replaced. Because it is just shifting from a gas to a liquid inside of the coils, it should last forever. Studies show, however, that as a result of this process up to 10% of the refrigerant is lost each year as it permeates through the system. Less gas means less cool air in your system of course, so refilling every few years will keep your air con working in tip-top condition.

Aside from keeping your cabin cool, there are other reasons to make sure your air con is working as well as it can. You can also improve your fuel efficiency if the refrigerant is at its capacity, as there is less strain on the system and engine. 

Air conditioning doesn’t just provide in-car comfort during the hot summer months; it can also be used in winter to demist your windscreen, which is another important reason to recharge your air conditioning unit. Air con systems create dry, warm air instead of the usual humid air outside in winter which can clear your windscreen much more quickly than your regular blowers.

How often should I recharge my air conditioner?

When to get air conditioning recharge is an important question, as the service isn’t always the cheapest. Air conditioning is not checked as part of an MOT test so it is important that you include recharging as part of your regular vehicle maintenance routine. How long aircon gas lasts in a car depends on the car maker, but most manufacturers recommend that you get your air conditioning regassed once every 2 years.

Is it possible to recharge your air conditioning yourself?

The cost of air conditioning recharge is one of the reasons some people might consider doing this DIY. At a garage the prices are usually fairly standard and they depend on the type of refrigerant gas your car uses. The vast majority of cars on the road in the UK use one of two types of refrigerant – R134A and R1234YF. If your air conditioning system requires R134A gas the cost to recharge is £49.95. For vehicles that require R1234YF gas the cost is £129.95 to recharge. In short: this is quite pricey. 

You can, however, buy air-con regas kits if you want to try this yourself and save some money. If anything goes wrong, though, you may be left with a very expensive repair bill. Specialists may also have a better idea of how to check for leaks and other problems with the air-con system. There are also some safety issues to be aware of too. If the refrigerant gas comes into contact with your skin or eyes, it could cause painful freeze burns.

 You’ll need a canister full of refrigerant and a valve to attach it to the AC system,  as well as screwdrivers, goggles, gloves, and your car’s handbook or manual. One can of gas and a valve usually cost around £60 and you get a £10 refund when you bring the valve back. One canister can be used to fill up three AC systems, so in theory you will make  big savings compared with the prices at the garage.

If you want to do it yourself, there are three stages: Locate the air con filling port, attach top up gas, and simply fill up. 

 Use your handbook or manual to locate the air con top up port,  often referred to as the low pressure port. The handbook will also tell you what kind of gas you need to buy if you aren’t sure. Some covers under the bonnet have to be removed before gaining access to this port. 

 Remove the plastic cap that is often fastened using screws and bolts and attach the valve.  Turn on the engine and set the air con to the coldest setting. Run it for at least three minutes and then check the pressure on the valve. If your air con needs to be regassed, the valve will usually give a low reading (in the white area).

 Shake the gas canister and then connect it to the valve.  Top up by pressing the trigger for a few seconds. Go back and check the pressure again for an updated reading. Keep going until it is in the green, so above 25 PSI. Before you are finished, check the air con once more by turning it on and it should be blowing cold. If the air con doesn’t hold pressure and it can’t get to the green section on the PSI gauge then there is likely to be a leak somewhere in the system and this will need a specialist to check and repair it.

Do air conditioner recharge kits work?

Air conditioning recharge kits have the potential to save you a lot of money. But, do they work? The short answer is: Sort of. 

Yes, they can absolutely top up your system’s air conditioning refrigerant so that it will blow cold air again.

However, since your vehicle’s refrigerant should last forever, if your sealed AC unit is losing refrigerant it could be because you have a leak. If your refrigerant can leak out then air and contaminates can get in and this is extremely bad. 

Now a small leak isn’t so bad. A £15 recharge yourself may reinvigorate the system with refrigerant for the entire summer season if the leak is not that big. The same problem will crop up again the following year, but as long as the leak hasn’t gotten worse you can repeat the process and avoid going into the shop and having a costly repair. Some people treat this as part of their yearly car maintenance. Some kits also come with a sealant to help get rid of any tiny leaks, which is an added bonus. You have to be careful though – putting anything into a system that your manufacturer doesn’t recommend has the potential to have some undesired effects. 

A recharge kit only injects refrigerant into the system. It doesn’t get rid of any contaminants from your system and clear it out  and an AC machine is needed in order to decontaminate all of the air in the system. If there is a leak, it will also mean that while a kit will recharge the AC temporarily, it is going to lose refrigerant much faster. 

There is also the added worry that if you use a recharge kit yourself with little or no experience,  you could over-pressurise the AC system and cause premature compressor failure. This can be very expensive. It might be worth it to pay a garage to recharge your air conditioning than to pay the repair costs. Taking it to a garage will also get added services, like changing the compressor oil, that will be critical in helping to keep your AC system running well, especially if it is in a car that is over 4 or 5 years old.