why does car air conditioners cause car to use more petrol?

Answer 1

Wow, this question is almost identical to one I answered yesterday.
Ok, when you turn the Air con on in the car, a clutch engages the compressor, which is driven by a belt from the engine. Because of the extra load on the engine, the engine has to work harder to maintain the same revs, therefore using more fuel. Its like any electrical device in the car also, the more electrics you are using, the more load is on the battery, so the alternator, belt driven off the engine is also adding load and reducing your fuel efficiency.
However, at speeds, using Air con is more efficient that driving with the windows open.

Answer 2

the normal car air-cond relies on a compressor to get the aircond gast pumping round the coils and so on to get cooled. the compressor is spun around using a fan belt attached to your cars main pulley, when the temp is not cool enough, a magnetic clutch will engage and the compressor will start pumping. With this additional weight (power needed to turn the compressors) and friction more torque is needed hence hhigher fuel consumption.
Electrical items in the car do not cause higher fuel consumption because the power needed to pull the alternator remains the same all the time. The alternator will continue to charge the battery to supply the voltage needed and it is usually stable to control the voltage no matter how hard you rev it.

Answer 3

Actually I have just seen a Test between two identicle vehicles driven with exact amount of Petrol (Gas) . One with windows up and Air On ..
The other windows down and Air OFF. Both travelling 55mph constant.
In theory the one with AIR ON should run out of fuel first.
But Aerodynamics are lost with the windows down.
The Results were................Inconclusive..lol. Too many variables.
A car does use more power to run the Air Con. Especially climbing a steep grade ....very noticeable.

Answer 4

the airconditioning system comprises of a compressor(which is usually belt driven by the engine), a condenser, return hose etc. the relevant part here is the compressor. the compresor by the mere fact that it relies on the engine to run adds load to the engine just like carrying extra fifty kilograms will add to engine load.
therefore it logically follows that efficiency is reduced thereby increasing petrol consumption in relation to the rate of consumption without the extra load. this especially applies to german cars(benzes, bimmers and the like) but is difficult to notice in japanese cars.

Answer 5

Any function used in the car (A/C included) uses electricity. Electricity is produced by the engine through the burning of petrol. If you need to use more electricity to run more functions in the car, you use more petrol.

Answer 6

Four horse power required to turn most A/C compressors at 4,000 rpm compressor speed. Some use less power at slower speed Variable displacement compressor on the Nissan Maxima

Answer 7

Because some of the power from the engine is being used to operate the air conditioning and therefore you need to press the accelerator slighly harder to maintain the same speed

Answer 8

Because it takes away from the horsepower of the engine to turn the air conditioner compressor.(that's what make it get cold)

Answer 9

because the compressor puts load on the engine - you can't get something for nothing you know.

I drove a hire Honda Civic in the sates with aircon...you had to turn it off to overtake !

Answer 10

THE AIR CONDITIONING SYSTEM HAS A PUMP AND IS DRIVEN NORMALLY FROM A DRIVE BELT FROM THE ENGINE. THIS PUMP IS QUITE HARD TO TURN AND MAKES THE ENGINE WORK HARDER, HENSE THE HIGHER FUEL CONSUMPTION.