No, Margaret.

The air conditioning is powered via the engine (usually via a V-belt). In order to lower the vehicle temperature and dry the air, it is necessary to pass the incoming air over a chilled matrix (Radiator in reverse). To chill this matrix, a gas in a compressor is pressurised via the above V-belt. In order to pressurise the gas, it takes lots of power from the engine, and the engine management system increases the fuel into the engine to prevent it from stalling. - Hence the extra fuel and associated cost.

The air conditioning system will cut in and out depending on its temperature settings and the ambient temperature. The hotter outside and the colder you set the internal temperature the harder the system has to work. I had a car that I always turned the aircon off as I approached a junction because if I was about to pull away and the aircon just happened to cut in I lost sufficient power from the engine to pull away speedily.

Any clearer now?

I think I'm following this, but are you saying that the air conditioning comes off the battery, so that using the battery means you are using less of the fuel in the car? As you can see, I am a non driver.

Margaret,

Think of the air conditioning as a fridge unit. It chills and dries the air coming into the car to keep you more comfortable. The lower the temperature, the harder the fridge has to work, hence it saps engine power. So by raising the temperature you are putting less load on the engine and hence it won't be using quite as much fuel.

I personally wouldn't have the air conditioning on a car with an engine smaller than 2 litres, as when the air conditioning is working it can really sap the power.

Hope this has helped?

I was reading this morning something I don't quite understand.
The article said, that if drivers increase the temperature of the air conditioning by 3 degrees C. it means that there is a saving of fuel. How can this be?

Thanks.