Air Conditioning Buyer's Guide


A blast of cool, refreshing air will certainly keep everyone happy on long car journeys when the sun is shining. But, as with many car components and consumables, the gas used to cool the air before it enters the cabin will eventually deplete.

That’s how you know when to top up your air conditioning.

Halfords air con services

When the refrigerant levels in your air con run low, your air conditioning becomes less efficient. Eventually, it’ll blow out warm air - not what you want on a warm summer’s day! Most of the time, if your air con starts blowing out warm air, it means you need to top up the refrigerant – you can get your air con checked at one of our retail stores with a Free Air Con Check (and topped up via our Air Con Recharge service for an additional fee).

If there’s been a sudden drop in temperature or you think there could be a leak in the air con system, then it’s best to book an Air Con Diagnostic at one of our 600+ garages.

Free Air Con Check

During this check, one of our trained technicians will assess:

  • your car’s current output
  • the capacity of gas in the system
  • the air temperature when the system is on.

We’ll give you a full report and recommendations so you can make an informed decision.

You can book our Free Air Con Check online or head to your local Halfords store.

Book Free Air Con Check

Air Con Diagnostic

During this check, one of our ATA qualified technicians will carry out:

  • a temperature check
  • a refrigerant check
  • an inspection of key components, including the compressor, condenser, drive belts and hoses
  • a leak test (using nitrogen).

We’ll give you a full report and recommendations so you can make an informed decision.

You can book our Air Con Diagnostic online or head to your local Halfords garage.

Book Air Con Diagnostic

Halfords Air Con Recharge

If your air con refrigerant does need topping up, we’ve got you covered!

Through our Air Con Recharge service, we’ll top up the gas in the system and give everything a clean with an air con cleaner to ensure bad smells are taken care of. You’ll soon be enjoying cool, fresh air again.

Cars on our roads currently require one of two types of gas: R134a or R1234yf (which is for newer cars). We’ll always ensure we use the correct gas for your particular car.

For most cars we can provide an online quote for the specific gas your vehicle needs based on your registration number.

If you think you just need a top-up at one of our retail stores, then we’ll first need to do our Free Air Con Check.

If you think you may need a more thorough check at one of our garages, you can find out more here.

Book your air con service

How to top up air con refrigerant yourself

If you want to have a go at topping up the air con refrigerant by yourself, it’s important to follow the instructions carefully as releasing the gases can be harmful to the environment.

Below we’ve provided a handy guide to topping up using the A/C Pro R-134a Recharge Gas and the A/C Pro Air Con Digital Trigger and Gauge.

Remember, you need to get the right type of gas for your car, as gas types differ from vehicle to vehicle depending on age and model. If you’re not sure which gas you need, check out our Vehicle Registration Number tool. You can enter your registration number and it’ll display compatible gases. Alternatively, head to your local Halfords store and one of our expert colleagues will guide you. Check out our full range of air con gas refrigerants here.

Before starting, make sure you’re wearing safety gloves and protective glasses.

Step 1 - Prepare

To start, you need to open up the bonnet and find the low-side pressure service port. This is located on the widest pipe connecting to the air con (there are two), usually between the AC compressor and evaporator. The hose provided with AC Pro’s products is designed to fit this port, so you’ll know when you’ve identified it.

Once identified, remove the port’s cap and start your engine and air conditioning. The air con needs to be on full capacity with maximum cooling and recirculation activated. Keep it going for three minutes and ensure the engine’s compressor is running and the clutch is engaging.

After this, connect the A/C Pro Air Con Digital Trigger Gauge to the port using the quick-connect hose.

Step 2 – Measure refrigerant

With the car still running, you can use the A/C Pro Air Con Digital Trigger Gauge to perform a diagnostic check. Easy to use, this device provides a PSI reading along with required actions based off this. There’s also a progress indicator along the screen which displays charging progress.

With the device connected to the port, check the reading. You will see one of four possible readings:

  • Caution, abnormal leak – see instructions
  • Pressure is low, squeeze trigger to fill
  • Pressure is good, fill until vent air is cold – do not overfill
  • Caution, pressure exceeding recommended levels – see instructions

Use this reading to guide you on your next steps. If you’re unsure, you can also refer to the label on the cannister.

If the pressure gauge comes up with ‘warning’, there is a problem with the system and you should not attempt to top up the refrigerant. Instead, you should get it checked out by trained technicians, and the easiest way is with our Free Air Con Check.

Step 3 – Top up the refrigerant

If the gauge says, ‘pressure is low’, the refrigerant needs topping up.

Disconnect the gauge from the port. Take the A/C Pro R-134a Recharge Gas and give it a thorough shake before attaching it to the gauge by screwing it on.

With the engine still running, reattach the gauge to the port. You can then start recharging the refrigerant. Doing so is easy. Just squeeze the trigger on the cannister while shaking the can. Make sure you keep the can upright throughout the process.

Stop every so often to check the pressure level using the gauge. The gauge will indicate, ‘Filling, release trigger in 15 sec. to read pressure’. Keep filling and following this release instruction until the filled message appears. It’s important to closely follow these messages so you don’t overcharge it.

When the needle reaches the green zone and the car blows cold air, you’re done. It’s that simple!

Air con cleaning at Halfords

If your air con is working fine but has picked up a nasty smell when it runs, then an air conditioning cleaning can is a quick solution that will last longer than an air freshener. These sprays work by turning the air conditioning to full then opening the can to let the cleaning gas out before closing all doors and windows. The gas will kill any mould and bacteria in the system, which are usually the causes of bad smells.

Shop air con cleaners

Air con canister deposit

If you do buy your own air con recharge can, then don’t forget to claim £10 when you bring your empty canister back into a Halfords store. As part of our recycling policy, we’ll happily take your empty can off you and refund you £10 – just make sure you bring your original receipt too.

Browse our full range of air conditioning products online and don’t forget to check out our air filters too – they’re also key to ensuring good air quality in your car and can even prevent allergens like pollen from irritating you as you drive.

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07/22