or welding lead to time and damaging soiling issues. The Lokring connection which is based on compressed fittings is easy to use and thus more time-efficient. Power consumption Although air conditioners use significant power, the drag of a car with closed windows is less than if the windows are open to cool the occupants. There has been much debate on the effect of air conditioning on the fuel efficiency of a vehicle. Factors such as wind resistance, aerodynamics, engine power, and weight must be considered, to find the true difference between using the air conditioning system and not using it, when estimating the actual fuel mileage. Other factors can affect the engine, and an overall engine heat increase can affect the cooling system of the vehicle. In a modern automobile, the A/C system will use around 4 horsepower (3 kW) of the engine's power, thus increasing fuel consumption of the vehicle. See also Sustainable automotive air conditioning References External links Heating, ventilation, and air conditioning 20th-century inventions American inventions Automotive cooling systems