Please resolve this ongoing argument re: air conditioning

Question

If you're driving a car and the air conditioning is on, you should roll up the windows, no? Having both the AC on full-blast and all the windows lowered is hard on the car, wasteful of gas, and makes you less cool as a passenger, right? Can you back me up (or prove me wrong) with sources, because I am SO sick of having this argument.

Answer 1

It's not wasting gas, but it's definitely wasting your car battery. Having your windows down makes the AC pretty much useless.

Answer 2

  You don t say if your a man or woman "DISCUSSING THIS" w/ which spouse but I vote w/ you lol Yes windows up it s less drag on the car w/ windows up.they act as a parachute type drag

Answer 3

A/C does dramatically reduces the fuel economy at any speed. By lowering windows also reduces fuel economy by causing drag.

Technically at low speeds such as stop and go city driving you get better gas mileage with the A/C off and windows open since there is very little aerodynamic drag at low speeds.At freeway speeds better gas mileage with windows up.

Of course if there is no aerodynamic drag from air coming in through windows there's little cooling effects from windows open. So looks like you both are right at some point.

Answer 4

An episode of "Mythbusters" on the Discovery Channel had this exact test about a year ago.  The following web site to the episode says--with scientific proof--that keeping windows down is the best result.

Answer 5

yes you do roll the windows up and if you roll the windows down and do what you are saying it will make it harder on the car and more expensive.

Answer 6

thats common sense if you dont have the window down then you have the AC on if the window is down then the AC is off who would argue with that its a waste of gas to use the AC and have the windows down cuz theres no piint!!!!!!

Answer 7

it is scientificly proven, plus ive proven it with my 1995 jeep grand cherokee and my moms 1998 chevy prizim and my uncles 2007 avalanche that that is total horsechit. Air conditioning has a very insignificant effect on gas milage. I tried goin the same place in all the cars, first with AC off then AC on, both times w/same gas milage in 100degree heat. Besides they put AC in cars to use it!

Answer 8

There are a couple of reasons to keep the windows up when running the air con.  

The AC is working to change the interior temp to comfortable.  I assume you would not have it on if the exterior temp is nice.  We put the windows up for the same reason we close a refrigerator door---to keep the cold air in.

Autos, in hot or cold weather have less wind resistance with the windows up.  If you have your windows up and the air on you help your engine work easier and save fuel (as opposed to AC and windows down).

Answer 9

yes you are correct, i just read a big article on the yahoo front page about it

Answer 10

having the windows down helps circulate the cool air. of course i never have my ac on full blast.

i've heard that it is a myth as far as the ac having anything to do with gas usage. but windows being down does create more air turbulence which can slow down a car. making one push more on the gas pedal in order to compensate.

next time, just tell the drive PICK ONE! having both is just overboard.

Answer 11

I totally agree with you, when having the AC on you should close the windows, if you don't you're just wasting the energy to cool the air leaving the car window! When the windows are closed you are actually cooling the air in the car, which is what you want.

Plus rolling down the window increases the friction, so that is another waster of energy.

Answer 12

It definately makes it warmer with the window open. I live in Florida and I absolutely hate it when my boyfriend opens the window to smoke. I mean, I'd rather that that him smoke with the window shut, but it makes the a/c a total waste because it's so hot outside!

Answer 13

Windows up/down makes no difference on the car's engine("hard on the car"), but the efficiency of the cooling effect is very diminished, and any time you use the A/C you are getting less fuel efficiency.  Anyone with any sense would keep the windows rolled up, but I have blown A/C in my convertible while driving under hot sun.  To me, that is the ONLY time to blow A/C without having all windows completely shut tight.

Answer 14

here they tested it on myth busters and your absolutely correct... heres the link to the episode they tested it on...its not a video but explains what they did

http://kwc.org/mythbusters/2004/11/mythb...

(its about half way down the page)

Answer 15

yeah you should only do one of the two at a time. people think having the ac off saves gas, but if the windows are down there is more pressure on the car. so you would have to press the gas more to compensate.  

Answer 16

From wiki....

An Air conditioner is a device that extracts heat from an area using a refrigeration cycle.

******

It is more than a fan, it is extracting heat from the air in your car and this takes energy.  If the windows are open than the area you are conditioning is to big for the air conditioner to be done conditioning therefore it will run continuously.

Answer 17

It only makes sense you would keep the windows up while AC is running. Sorry I have no sources just common sense.

Answer 18

Technically, I agree with you that windows should be closed when the air conditioning is on.

One exception, is when I first get into a car and turn on the air to cool it off. I open the sun-roof to let out the hot air then close the sun-roof once the air conditioner is fully working.

Answer 19

for me i cant have the ac on when im in the car cuz i get a headach but ur ryt u cant have both on its either the windows or the ac and as u know the gas prices r a killer now

Answer 20

It is harder on the car because of the wind resistance (drag) created by having the windows open.  Having the air conditioner only cuts about 1 mpg off your mileage (assuming the windows are up).   ~opinion~ It makes no sense to have the windows open, because  if you are cooling the air inside, opening the windows lets the warmer air in.  

Answer 21

Regardless of whether the ac is on or not the windows being down allows for more drag (at speeds over 40 mph) on the car which in turn diminishes fuel mileage. For driving around town the best fuel saving tip is to leave AC off and windows down.

Consumer Reports' auto-test department reports that the air conditioner reduces your car's fuel efficiency by up to 10 percent. So to achieve maximum fuel efficiency, motorists should avoid using the air conditioner at speeds below 40 mph and travel with their windows down, explains Gabe Shenhar, senior auto test engineer at Consumer Report's auto-test department.

"But as your speed increases to 45 mph, or highway speeds," says Jason Toews, co-founder of GasBuddy.com, "wind drag becomes an issue. Driving with the windows down increases the drag on your vehicle, resulting in decreased fuel economy by up to 10 percent. Drive at speeds over 55 mph with windows down and you'll decrease fuel economy by up to 20 percent or greater."

Answer 22

everyone knows its a fact that you have to have the windows up. air conditioners take in warm air from the room  then blow it over "cooling" coils and back into the room, the heat that was removed is then discharged outdoors... having the windows down defeats the object of having airconditioning

Answer 23

it shouldn't matter whether the window is up or down if you can not dial in the temperature that you want -- if there's no thermostat.

Answer 24

One wouldn't open all the windows in one's house and run the A/C full blast!

Windows down and A/C full blast is wasting energy!

Answer 25

Yes.

When the A/C is running and cooling the car, that means there is more drag on the engine, since a compressor is running off a belt on the engine.  This honestly kills about 10-20hp, and you will feel the car is slower.  When I race I never run the a/c, for that matter barely ever hah.

When the windows are down, you are just increasing the aerodynamic drag on the car slightly.

Both of these will decrease your cooling and your gas mileage.  Both mechanically with the A/C running, and Aerodynamically with the windows cracked or open.

I personally run windows down and A/C off when possible, meaning not too hot, and hopefully moving a decent speed.

Take Care.

Answer 26

You're absolutely right.

If you have BOTH the windows down and the air conditioning running, the engine is fighting the wind resistance to keep the car at the desired rate of speed AND powering the air conditioning at the same time. And yeah, it guzzles gas.