Does running the ac in a car burn up your gas--or is that a myth?

Question

Anyone can answer this one. Be it you're a mechanic, or own a car.

Answer 1

Hi there, having the AC on puts extra strain on the engine, as you have to run the AC compressor, thus you use more fuel, the AC compressor is usually run by a belt, taking its drive from the front crankshaft pulley, when the AC is off, the pulley is in free wheel mode, AC on and you drive your compressor, easy on the AC and save yourself some petrol, ooops gas, we call it petrol here in Oz.

Answer 2

Yes and Depends.

Yes, using the AC eats gas. Exactly how much depends on many factors.

The actual amount used depends on the make of your car, the type of AC, the horse power you have, the fuel efficiency that the car normally enjoys, and a little bit on the weather.

So, assuming that you are running the AC because it is hot, you have to consider your alternatives, which in this case, is driving with the windows down. At low speeds, some cars do better with the windows down. At high speeds, some cars do better with the AC on. Unfortunately, there is nowhere you can look up statistics to see under what circumstances the AC is better for your car.

One way to test your car is:
1) Fill tank
2) Run a significant stretch of road with windows down
3) Refill, and pay attention to how much goes in the tank
4) Run the same stretch of road with AC on
5) Refill, and again pay attention to how much goes in the tank.
6) Compare notes.

You could also do a test run with windows up and AC off to give you a base reading.

Answer 3

Hi
"One form of energy can only be converted to another form"
Yes running the AC will burn up your gas more.This is because the AC compressor takes its drive from the shaft by belt running through the main shaft,AC,Alternator,etc. So when the AC is ON it loads the Engine. But the level of burning depends on certain factors
1. If you are on a low speed and if the AC is ON it consumes more fuel.(sometimes you can feel the loss when you drive)
2. If you are on the highway at a higher speed and if you have a higher capacity engine then it hardly matters.(the load of AC on the engine is negligible and it takes it in ease)
3.It also depends on the AC you have installed in your Car and how well your car is sealed leak proof.(if you have a climate control one it will reduce the unnecessary running of the AC).

I have not considered the air drag in this because your question is not on that.

Answer 4

Yes! Using the A/C does use gas because of the extra work of the compressor. I have found that turning the thermostat up a little makes the compressor come on less and improves the gas mileage some.

Try to keep the windows down when you are in traffic or going slow. When you go fast with the windows down it creates drag on the car which could decrease gas mileage. So, roll up those windows when going faster and use the A/C.

Hope that helps
Matt

Answer 5

Yes, running the ac does use more gas, but not as much extra as in the "olden days". You also use more gas if your windows are down. So whether you drive with the ac or windows down, you are using virtually the same amount. Don't however drive with your ac on and your windows open, unless you own oil stock that is.

Answer 6

Gekko's right.

In fact, the drag from having the windows open actually causes the GREATER drop in fuel efficiency than running the AC.

Now, you can save the most gas by driving with the windows up and the AC off, but it's going to hit 97F where I live today, and I wouldn't recommend that, unless you enjoy a sauna.

Answer 7

ac unit includes a compressor that it run with the help of a belt directly linked to engine when we4 switch ac on compressor comess into action and strts compressing the cooling gas and this puts a certain amount of load on the engine other than the load it had for running the car hence u end up with lower mileage

Answer 8

Running the air compressor takes energy from the engine to compress the refrigerant so yes, it does tax your engine thus needing more energy from gas. However, with modern vehicles this amount is very small and some say that on highways leaving your windows down creates enough drag to offset any gas savings by not running your air.

Answer 9

The myth busters solved this one.You use far less gas with tha A/C off and windows down.besides people leave there cars running with the A/C on that uses gas.

Answer 10

In my experience, running the ac in your car puts a strain on the alternator, which makes your car run less efficiently. Less efficiency = less gas mileage. So, I would have to answer yes to your question.