Why does air conditioning in a car make the car use up fuel more quickly?

Answer 1

I just answered the same question yesterday, or atleast very similar. The question was what uses more gas, A/C or Heater.

Here is a copy-paste.


The air conditioner wastes more gasoline, hands down.

Turning the heater on uses heat energy all ready stored in your cars coolant system to warm the air in the cabin. This is why your heater does not work until the car has been running for a few minutes. This energy is all ready in the car if you use or or not.

The A/C on the other hand activates a compressor which requires more electricity from your cars alternator to run. The energy to power the compressor has to be converted by the alternator, making your motor work harder. Some cars also have an additional fan that turns on with the A/C to help keep the alternator cool as it too works harder. This fan also draws power though, creating an even greater load for your motor.

If you wanted to test this, let your car run for a minute or two until its at its normal idle RPM. When you click the A/C on you will most likely see the RPMs on the tach increase. This is your motor compensating for the additional work it is doing by increasing the rate at which it works (RPM).

Sorry for sounding like a science teacher, hope this helps and lets you shut your friend up =)

PS: Using the A/C will cause you to burn more fuel if your on the freeway or in the city, either way.

PSS: Often times, rolling your windows down will cause you to burn even more gas than using the A/C, at least while at freeway-speeds of 60+. This is because you are creating much more aerodynamic drag with the windows down. It depends a lot on the vehicle your in, but more often than not this is true.

Answer 2

When the air compressor kicks on, there is a bigger load put on the engine. That can increase fuel consumption just like if you were driving up hill.

In modern aerodynamic cars, you can use more fuel with the windows open, so it is likely that the trade off makes little difference.

Open the windows or run the air....the result will be very close to the same.

Answer 3

When you turn the air conditioner on, it engages the clutch on the front of the pump unit which is driven by a belt from the motor thus creates drag on the motor using more fuel. The harder the engine has to work, the more fuel it uses. Running the air conditioner usually cuts gas milage by 1 or 2 MPG.

Answer 4

If the car is properly tuned up, then it shoudl not use anymore fuel than it would if you ran the car with the windows down. The compressor adds more load to the engine thus making it work harder to keep turning when the compressor is on.

Answer 5

SO SIMPLE mate, its because when you turn on the conditioning system more energy is used... so some of the power which makes the spark plugs burn the fuel at a higher level is reduced.....that's when you see the car giving to much smoke as fuel is wasted- because of not being burn at a higher level to give high performances which boost your acceleration & speeds.

Answer 6

The ONLY thing you can use on a car that doesn't affect the fuel consumption is the radio(not cassette or CD), it all puts extra strain on the engine, opening the windows is not efficent either as this affects the aerodynamics of the car.

Answer 7

The air conditioning compressor is driven by the engine. This uses power and hence more fuel.

Answer 8

Because it takes more energy to run the AC compressor and the source of energy in a car is fuel.

Answer 9

Therres a coppressor in the car that draws more on the engine requiring the engine to work harder which in turn uses more gas. You also lose some horsepower when using the AC also.

Answer 10

Your engine has to drive the A/C compressor, drawing several horsepower from the engine. More load on the engine means power fuel to produce that power.