Manufacturers recommend for the fluid in your air conditioning systems to be recharged once every two years In fact, as much as 10% of the gas within your air-con system can leave your vehicle each year, which is why you’ll need an air-con regas to keep your car nice and cool. Remember that your vehicle’s air-con system isn’t looked at during the service or MOT, so if your vehicle is over two years old, it’s likely to be due for an air-con recharge.