If I use the heater in my car, does it chew up petrol the same way as using the air conditioner?

Answer 1

The heater uses an electric motor so it has no effect on engine performance, since the engine produces heat simply by running. The AC will use slightly more fuel because the compressor creates a drag on the engine. It is true that the AC compressor pully is always turning when the engine is running, but the compressor does not engage until the AC is turned on.
By the way, most people who use their AC have their windows closed, which reduces aerodynamic drag on the vehicle, so there is just a slight difference in fuel mileage between using the AC and driving with your windows open.

Answer 2

OK let's stop guessing or pretending we know how the HVAC system works. Reading form above some people are just plain guessing
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When the A/C is on the car turns on a clutch that turns the compressor. When the A/C is off the compressor is NOT spinning. The A/C compressor is NOT always turning.

When the heater is on, it sucks some heat off the radiator fluid (the same heat that would have gone to the outside air). The only extra "power" you would be drawing is the electric motor (driven by the alternator / generator attached to the engine). But that is a very minor draw.

Answer 3

no... the heater is only taking heat from the engine cooling system and you are using an electrical motor to circulate the air..... and with the A/C you are using power from the engine to turn the compressor.......

Answer 4

Actually, neither "chews up" fuel, since the a/c compressor is always turning anyway. The only thing that changes is a very slight additional draw on the electrical system, which will have negligible noticeable difference in mileage.

Answer 5

no. a/c is turning the compressor and the heat does not.

Answer 6

no. a/c has to run a huge compression inorder to cool.

Answer 7

No, it does not.

Answer 8

uh no........