Air Conditioning

oulu

Just wondering if you use are conditioning in a car does this effect fuel consumption, someone said it uses alot of petrol to run AC in car is this correct

Anan1

oulu wrote:

Just wondering if you use are conditioning in a car does this effect fuel consumption, someone said it uses alot of petrol to run AC in car is this correct

The a/c compressor is run off the engine, so yes it does use fuel. On the other hand, so does having a window open at 130km/h, due to aerodynamic drag. The fuel penalty incurred through the use of a/c is small enough, personally I have never noticed it.

mike65

First hot day of the year and two air-con questions!

Mike.

AlanD

I've checked several times using some accurate fuel consumption techniques with and without a/c and you'd want to be travelling huge huge distances with it on over a year to notice the difference.

Fuel consumption because of A/C is minimal. Those who tell you it'll cost you a fortune have no idea what they are talking about and probably never had A/C and may never have because of their ignorance.

I'll never have a car with A/C again.

How did we ever survive?

spuddy

Consumption goes from 0.5l/100kms to 0.7l/100km on tick over with a/c on. So not much.

BrianD3

Haven't used the air con enough to say anything definite about how it affects mpg. Seems to make little or no difference at 60 mph. Might make more of a difference when stuck in traffic. One thing's for sure though, it saps power in my car eg when taking off it bogs down much easier. However I only have a measly 1.6 litre petrol engine, would porbably notice it much less in a bigger engine

gerrycollins

it depends on which A/C you have
Mehanical or electrical

Mechanical is cars with the A/C button and then the general controls for heat/cold so you can have it really cold or hot but the reaility of this is that it just ionises the air hence the dried lips and throat when you set it to cold. I had this in a Peugeot 307 and to be honest you only needed it on for a few mins at a time otherwise over long distances it would use a lot of fuel,but mostly on short distances i never noticed any great drop in fuel

Electrical is the one where you can set the temp to a desired setting,this one does use up a fair amount of fuel as it works harder to maintain the setting where as the other option is just set cold. This one also is less hars on the dry lips and throat,Had a different 307 for a few days with this in it and using it in the manner i did notice a greater increase in the consumption considering the cars were identical except for the kind of A/C in each

Pherekydes

I hardly ever use the AC here, but when we go to France on hols, it's on all the time. I didn't notice increased consumption. However, I did notice a loss of power, which is the reason I never have it on here.:D

crosstownk

I have a Passat TDI Auto with Climatronic and have tested it quite a few times to see if the A/C uses much fuel. Basically I do city driving most of the time. I reset the odometer with each tank fill and I always fill as soon as possible after the warning light comes on. Over a 6 month period last year I recorderd the mileage from a full tank with A/C both on and off. I got 420 miles to a tank with the A/C off and 400 with it on. These figures are averaged over many fills. So really it's not that much tbh.

bazz26

Yes, I have climate control and use it alot even when it is not warm. It is great for keeping the condensation away on a wet day when you have a car full of people.

Haven't really noticed any substantial difference in mpg to be honest. Cannot be any worse than when having the windows down or sunroof open at 100kph caused by a higher drag coefficent.

unkel

AlanD wrote:

Fuel consumption because of A/C is minimal

Depends what you call minimal. In this country it would not add much in most cases as it doesn't do much in the first place, but try setting the automatic aircon in the south of France in the summer driving a black car in the sun with the outside temperature (in the shade) of 40C and I'd wager your fuel consumption would increase by 30%

AlanD wrote:

Those who tell you it'll cost you a fortune have no idea what they are talking about and probably never had A/C and may never have because of their ignorance.

I take it you refer to people using aircon in Ireland where it doesn't do much and it doesn't cost much

AlanD wrote:

I'll never have a car with A/C again

why?

Ok it does use more fuel and it's not very useful in Ireland 99% of the time, but then again it can come in handy occasionally (very wet weather / hot weather and travelling at speed and window down is noisy and not fuel efficient)

Esel

spuddy wrote:

Consumption goes from 0.5l/100kms to 0.7l/100km on tick over with a/c on. So not much.

40% increase = not much???

Anan1

esel wrote:

40% increase = not much???

Maybe he means from 10.5l/100km to 10.7l/100km when driving? Or maybe there's a glitch in his trip computer that tells him he's getting insanely good mpg "on tickover" (whether this means idling or coasting, I don't know)?

endplate

They tried the theory on Mythbusters once which uses more fuel windows open or air con on. They used a trip computer first and it said windows open uses more fuel. Then they filled 2 identical cars opened the windows on one and left the aircon on in the other and drove around an oval track at the same speed and the car with the aircon stopped first.

I've noticed in my car on a long journey I can hit 46mpg but with the climate control on I hit about 40mpg big difference. I leave it on regardless as the car is very comfortable to be in on a long journey

Stephen

I saw that episode of Mythbusters, but one problem with the way they did it is that cars they used - big, hulking, gas-guzzling boxy SUV's with the aerodynamic properties of a double decker bus - i.e. opening the windows is going to make bugger all difference with them. I'd imagine if they used something sleeker and more efficient they'd have got more interesting results.

Henry Ford III

Slow coach wrote:

I hardly ever use the AC here, but when we go to France on hols, it's on all the time. I didn't notice increased consumption. However, I did notice a loss of power, which is the reason I never have it on here.:D

You really should use it weekly at least for perhaps 15 minutes.

The refridgerant is also the lubricant of the sytem and periods of unuse will cause the rubber pipes to perish eventually. Repairs are not cheap either.

Henry Ford III

gerrycollins wrote:

it depends on which A/C you have
Mehanical or electrical

Mechanical is cars with the A/C button and then the general controls for heat/cold so you can have it really cold or hot but the reaility of this is that it just ionises the air hence the dried lips and throat when you set it to cold. I had this in a Peugeot 307 and to be honest you only needed it on for a few mins at a time otherwise over long distances it would use a lot of fuel,but mostly on short distances i never noticed any great drop in fuel

Electrical is the one where you can set the temp to a desired setting,this one does use up a fair amount of fuel as it works harder to maintain the setting where as the other option is just set cold. This one also is less hars on the dry lips and throat,Had a different 307 for a few days with this in it and using it in the manner i did notice a greater increase in the consumption considering the cars were identical except for the kind of A/C in each

I'm not so sure about this one.

A/c, whether it's simple a/c or climate control works identically. Both use an engine driven compressor.

If the simple a/c is too cold, turn the temp of the cars heating system up. Climate control attempts to do this this automatically and keep the temperature at a set level.

Either will dehumidify the air and cause a dry throat. Drinking water avoids this.

unkel

Stephen wrote:

I saw that episode of Mythbusters, but one problem with the way they did it is that cars they used - big, hulking, gas-guzzling boxy SUV's with the aerodynamic properties of a double decker bus - i.e. opening the windows is going to make bugger all difference with them. I'd imagine if they used something sleeker and more efficient they'd have got more interesting results.

Yes that would make a significant difference. Two other major factors:

1. Speed of the car. At 50km/h it makes, to quote you, bugger all difference that the window is open. At 150km/h in a family saloon, it could well make 30% difference

2. Temperature outside and inside (aircon) car. The bigger the difference between the two, the more fuel is consumed

Looks like that program didn't really give any useful answer...

I'd like to know what percentage extra fuel is used with the drivers' window fully opened @100-120km/h in an average family saloon and how much is used to cool the car down 10C. My guesstimate for both would be in the region of 10-15%

Pherekydes

Henry Ford III wrote:

You really should use it weekly at least for perhaps 15 minutes.

The refridgerant is also the lubricant of the sytem and periods of unuse will cause the rubber pipes to perish eventually. Repairs are not cheap either.

Thanks for the tip: will do so from now on. Seeing as today is nice I might need to!