It's a button you can find on the dashboard of just about any car - but not all motorists are aware that it can make driving in summer a lot more bearable and save them money at the same time.

The air recirculation button positioned within the array of temperature controls in your vehicle is most effective during hotter months.

This is because it cools the cabin quicker and more economically than using the default external air ventilation setting.

And because it puts less of a strain on your air conditioning system, it has fuel-saving benefits too.

Motor mechanics also recommend drivers who suffer from hay fever make use of it, especially if they haven't had the cooling system in their vehicle serviced for some time.

Here's an explanation for when it's most effective - but also why you shouldn't leave it running for too long.

The Air Recirculation button can help reduce fuel economy, cool the cabin quicker and block unwanted smells. But drivers shouldn't use it at all times...

There is a universal symbol for the air recirculation button; it shows the outline of a car with a curved arrow within it.

Activating the button shuts off the flow of air being introduced to the cabin from outside and instead - as the name suggests - recirculates the air already in the vehicle.

Using this button will accelerate the time it takes to reduce the temperature inside your car when you first get into it on particularly warm days or during prolonged heat waves.

Rather than entering a scorching car and blasting the air-conditioning and having to wait for it to cool down, experts suggest opening the windows and doors for a few minutes to let all the built-up hot air escape.

This also helps to eject toxins that can be released from interior materials - such as formaldehyde, a preservative used in seats and dashboard plastics - during prolonged exposure to heat.

After a minute or two on the move and letting the air-con cool air being introduced to the interior from outside, drivers should then switch on the recirculation function.

Doing so means the car's air conditioning system will continue to recirculate that cool air rather than having to work much harder to continuously reduce the temperature of warmer air being drawn into the cabin from outside.

This has a number of cost-saving benefits.

Some cars won't have a separate 'Fresh Air' or 'External Air' button. Those that do will have one that looks like this with an outline of a car and an arrow entering it. Here's when to use it

Firstly, by putting less demand on the air-con to cool hotter air being introduced to the cabin from outside, there is less strain on the 12-volt battery. In turn, this should provide better fuel economy.

Reducing the burden on the air-conditioning unit in your car to treat external air before pumping it inside can also lower your maintenance costs.

By lowering the intensity of the job of the air-con will delay the need for a re-gas or recharge, which typically costs between £50 to £200.

And it will also prolong the life of the cabin filter designed to trap dust and - importantly for hay fever sufferers - pollen to stop it being dispelled into the car.

Matt Wrankmore, head of garage network at FixMyCar, told us: 'Like any filter, the cabin filter needs replacing regularly. If not, it becomes dirty and clogged and will no longer be filtering the air, instead allowing the pollen and allergens to come directly into the car.

'Not only can a pollen-clogged filter exacerbate hay fever symptoms, but it can also impact airflow meaning cooling and heating in the car is affected too.'

Matt says pollen filters are generally replaced as part of a full service but not minor interim service. However, just 22 per cent of drivers polled know this.

In a survey of over 1,000 motorists this year, three in ten believed that pollen filters are replaced in both a full and interim service.

Speaking to 55 garages on its network, FixMyCar also asked how many cars the garages see every month that have not had a full service in over a year.

Matt adds: 'With a new pollen filter fitted, keep your windows closed, turn your air recirculation on and enjoy a symptom-free journey. Just remember to replace the filter every 12 months or 15,000 miles.'

Other benefits of the air circulation function

It is also the choice setting when sitting in heavy traffic or following slow-moving vehicles churning out lots of exhaust pollution. By blocking this dirty air entering the car, you can avoid breathing in the fumes.

This can also be said about blocking unpleasant smells - such as driving past freshly-manured fields. If you are aware of a particularly whiffy location, make sure you have turned on the Air Recirculation button before passing.

The air recirculation function is less beneficial in winter months. This is because it can increase the humidity inside the car and cause the windows to steam up quickly

When not to use it

Despite all the benefit, drivers are urged not to use this setting for extended periods because the air in the car can become stale and stuffy.

Prolonged use, especially in winter, can increase the humidity in the cabin and cause the windscreen and windows to steam up.

Especially during long, arduous motorway trips, breathing the same recirculated air for extended periods can increase a sensation of tiredness.

Those who smoke or vape while driving should not use the air recirculation setting for obvious reasons. It’s also worth remembering that it is illegal to smoke in a car if carrying passengers under the age of 18. If caught breaching this rule, drivers can be fined £50.