Does driving with the A/C on use more fuel?

[olfella]

The obvious answer to the OP is yes. By how much? Horses for courses. IMHO no good turning your AC off if it is going to cost big time in the longer run (regassing). I use 98 fuel and reckon I get better consumption from that. So any savings I make would still be an improvement as if say I used E10 and turned the AC off and that is my preference.

[FGX-351]

AC isn't that bad in the EL but AC Max on the other hand is noticably thirstier .

[ford man xf]

Was it Mythbusters that tested out whether having the air conditioning on or just having the windows down and which one used more fuel, I can't remember the results?

[usernametaken]

my FGII ute has AC on by default... even in sub zero temps.

[Shonky.]

I used to drive a 3cyl Charade and turn the ac off on hills - it was quite noticeable the power increase (felt like vtec kicking in!)

To me that would imply that on that weapon it would make a difference to fuel usage

[GasoLane]

Originally Posted by ford man xf

Was it Mythbusters that tested out whether having the air conditioning on or just having the windows down and which one used more fuel, I can't remember the results?

Haven't been keeping up, have you?

See posts 11 17 and 18

[Franco Cozzo]

I have mine on all the time, I use the heater to warm it up in cold weather.

It stops the windscreen from fogging up.

[FoxtrotGolfXray 5.0]

Originally Posted by 99AUXR

Sorry but I don't see why they shouldn't be run all the time, I service air con systems in cars at the workshop regularly have never seen an issue caused by an air con system being run all the time. The compressor will cycle every ~20 secs anyway if its got the temp sorted so its moot point anyway.

Just like the gas should be changed every few years but no one ever does

I think there's two different points being discussed. You are right, having the a/c on all the time does not cause any additional wear and tear than not having it on all the time.

But what NTF6 is saying is that you don't have to have the a/c on all the time to stop the wear and tear from happening.

Personally, I'm such a tight-wad that I don't have the a/c on unless I actually need to cool the air inside the cabin. I do not see any advantage in running the a/c when I am then just going to mix the cold air with hot air from the radiator to create the warm air I am after.

Even though those fuel consumption savings are small, I'd rather have that in my pocket than the servo company's

Of course I do run it for short periods of time regularly to keep everything in a serviceable condition. Plus, I hate the dyer air that I already have to put up with in the office for 8.5 hours everyday.

Craig H

[OCTANEBOSS]

A good practice when driving with AC on is not to flog it to much especially if it is custom tuned & fairly hot outside, it can cost you a lot more than extra fuel ( stress, motel, stress, Christmas lunch, hire car, stress & 1000 extra kms after boxing day and then you can start holidays). No fun driving a GT over the nullabor when there is a rental buzz box in the rear view instead of a an F6.... look back and laugh now finally, still got to eat mums turkey but it was costly . Slowing down will offset any extra fuel you may use with AC on but i prefer to be cool or fog free when cruising, would probably drink more beer if didnt have it on

[Davehoos]

I ran out of fuel in NZ with a crafter trying to find diesel station open when union test is playing.. returned 25L 100 on good runs.

you need the partition behind the front seats.and euro system not a air coller-its an dust reducer.

most of these systems are dealer fitted. the local dealer ordered in crafters with 2 compressors because to get a engine bracket was several $1K and you had to replace cooling pipes etc. that meant it had a industrial fridge compressor.

perconally most of these euro design-some come from south America etc are green house gas friendly-designed not to work.

big York compressor is one of the most efficient compressors around. it designed to work at lower rpm. the great big Harrison A6 compressor is the best compressor going for horse power per heat transfer.

most Australian cars from late 80-90 had scroll compressors. sanden TRS and mitubishi http://upload.wikimedia.org/wikipedi...croll_pump.gif


only a few cars these days with these as the don't suit variable capacity application-but are great for electric vehicles and domestic operations.

[LyleXR8]

A little off topic but we got a guy at work that says an aircon uses 4 hp or something like that, so driving a 2650hp truck when he's hauling a load up hill he'll turn the aircon off on steep bits to avoid dropping a gear!

[zlcrazy]

Originally Posted by Big Damo

I have mine on all the time, I use the heater to warm it up in cold weather.

It stops the windscreen from fogging up.

Thats what I have always done too.

[Yellow_Festiva]

As a percentage the increase will be higher on a small capacity motor. You could really feel the load on the Festiva when the air conditioning was on, and the increase in consumption could have been double digits percentage.

In a large capacity engine the strain would be far less, as would be the increase in consumption.

[Franco Cozzo]

Originally Posted by Yellow_Festiva

As a percentage the increase will be higher on a small capacity motor. You could really feel the load on the Festiva when the air conditioning was on, and the increase in consumption could have been double digits percentage.

In a large capacity engine the strain would be far less, as would be the increase in consumption.

We've only got 57KW in those Festivas to start off with in the bigger 1.5L, so that small loss feels huge

[NTF6]

Originally Posted by 99AUXR

Sorry but I don't see why they shouldn't be run all the time, I service air con systems in cars at the workshop regularly have never seen an issue caused by an air con system being run all the time. The compressor will cycle every ~20 secs anyway if its got the temp sorted so its moot point anyway.

Just like the gas should be changed every few years but no one ever does

Because every piece of equipment on your car has a finite life, use it more and it will fail earlier, pure and simple.

As for changing the gas every couple of years...what absolute rubbish. It is a closed system, that's like saying, oh we should get our fridge regassed and serviced every couple of years.

If there are no leaks in the system then it will run forever until one of the components fail.

Most people just don't understand how refrigeration works, thermal efficiency, latent heat. The first stinking hot day in a car and the aircon struggles, customer pulls into the fridgy joint and complains, fridgy joint puts the gauges on and everything is fine, simple fact is on a 43º day you can't get 8º off the evaporator. Then the fridgy charges you something like $70 or $80 bucks tells you he topped it up and away you go..

[AU1XLS]

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