How Often Should You Re-gas Car Air Con?

Many drivers are told to re-gas the air con every two years, but that is a rule of thumb rather than a requirement. A car air con circuit is sealed, and in principle it keeps its refrigerant for as long as every joint, hose and seal stays tight. In practice, tiny amounts do seep through rubber hoses and seals over time, so performance fades gradually.

What matters is how the system is behaving, not the calendar. Below we explain what a re-gas actually involves, which signs suggest your car is due one and how to avoid paying for a top-up that does not last. Automaster is a garage at Longcombe Cross near Totnes, and this is the advice we give when owners ask us.

Does a car need its air con re-gassed every two years?

Not necessarily. Vehicle makers do not all publish the same schedule, and some say nothing at all about routine re-gassing for a system that is working. Your handbook or service schedule is the place to see what applies to your car.

What is true is that older systems, and those that spend long periods unused, tend to lose a little gas and may benefit from a check sooner. A car that still blows properly cold does not need its gas changed just because two years have passed.

What are the signs that the gas is getting low?

Loss of refrigerant is rarely sudden. You may notice that the air takes longer to cool the cabin, that it is cold at motorway speed but only cool in traffic, or that the cooling that once felt strong now needs the fan on full.

Other signs include a compressor that clicks on and off more often than before, or one that does not engage at all, because many systems have a pressure switch that stops the compressor if the gas level is too low.

• Cooling slower than it used to be
• Cool rather than cold air on warm days
• Compressor cycling on and off rapidly
• No cooling and no compressor engagement
• Oily residue on air con pipes or fittings

What actually happens during a re-gas?

A proper service is more than squirting gas in. The machine recovers whatever is left in the system, pulls a vacuum to remove air and moisture, checks that the vacuum holds, and then refills with the correct type and amount of refrigerant and lubricant for your vehicle. Different cars use different refrigerants, and the quantity is specific to the model, so we work to the manufacturer data.

The vacuum hold is useful because it can show a leak. If the system will not hold a vacuum, a simple recharge would be wasted and the leak needs finding first.

Is a re-gas the same as a top-up?

They are different. A top-up adds gas to whatever is already there without knowing how much was lost or whether the system is contaminated with air and moisture. A full re-gas empties the system and fills it to the exact specified amount, which gives a clearer picture of the system's health.

Moisture in the circuit is a quiet problem, because it can corrode components from the inside. That is one reason a full service is usually better than topping up from a can.

What affects the cost and when should I book?

The cost of an air con service depends on the vehicle, the type of refrigerant it uses and whether any leak repair or replacement parts are needed first. A straightforward service on a system that holds its gas is a smaller job than one where a hose, condenser or compressor has to be replaced.

If your air con is still performing well, there is no harm in leaving it alone. If cooling is clearly weaker than last summer, or the system has not been used for a long time, ask for an inspection. We will test before we recommend any work, and we are happy to give a quote once we know what the car needs.