How much extra fuel does AC use?

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RichM

RichM

Well-Known Member
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Does anyone know how much extra fuel AC uses in the TD4? I never used it during the summer because someone told me it uses 10% more fuel. Instead, I just put the blower fans on full.

Anyone know whether or not this 10% figure is accurate?

Cheers

Rich
 
RichM said:
Does anyone know how much extra fuel AC uses in the TD4? I never used it during the summer because someone told me it uses 10% more fuel. Instead, I just put the blower fans on full.

Anyone know whether or not this 10% figure is accurate?

Cheers

Rich
Click to expand...


Does seem to be an average figure quoted by many. Some cars will be less I'm sure.
 
RichM said:
Does anyone know how much extra fuel AC uses in the TD4? I never used it during the summer because someone told me it uses 10% more fuel. Instead, I just put the blower fans on full.

Anyone know whether or not this 10% figure is accurate?

Cheers

Rich
Click to expand...

Note that the gaskets can dry out if not regularly used. A rule is to have it work at least 10 minutes every month.
 
There is a programme on Discovery Channel called Mythbusters, they tried to find out the answer to this.

They used identical cars on a track, one with the aircon on the other with it off, the upshot was that they used about the same amount of fuel.
One because the aircon was on it used extra fuel.
The other used extra fuel because the windows were down and caused drag.

I'm not an expert but it seemed plausible and scientific to me.
 
If it was 10% you'd think it would be easily noticed but I've never noticed any difference either way.
 
Hoyt-Protec said:
There is a programme on Discovery Channel called Mythbusters, they tried to find out the answer to this.

They used identical cars on a track, one with the aircon on the other with it off, the upshot was that they used about the same amount of fuel.
One because the aircon was on it used extra fuel.
The other used extra fuel because the windows were down and caused drag.

I'm not an expert but it seemed plausible and scientific to me.
Click to expand...

I worked for a German Truck company, they did extensive wind tunnel tests and came to the conclusion that there was no increase in fuel consumption! As mentioned above if a window or windows are open the drag is very high. All efficiency windtunnel tests on cars are conducted with closed windows. Our tests also showed that it was much safer due to less driver fatigue leading to higher alertness!

OldManDisco
 
My freelanders Ac was on all the time and there was no difference at all you probley use more fuel if you have the windows open.

I did one fill up and turned the ac off for that tank and no difference
the car was a 1998 xedi rover diesel
 
I suppose when you consider how much power is needed to get a car to move, then an extra pully with a tiny pump int much. I don't notice the difference on mine. Some think the engine is dragged down when the air con is switched on, as the revs drop slightly at tick over when the air con is switched on. When your driving and the revs are higher, you don't notice the revs alter when the air con is switched on.
 
Less of a drain than if you have roof bars left fitted when not using them... Trouble is as a normal road user it is tricky to work it out as you never have the same road/traffic conditions twice.
 
I think the extra fuel used was more of a problem on very old cars with huge air con compressors, modern ones don't have this problem unless maybe for some 1 litre Korean type tiny cars where you cannot even accelerate when the air con is on!
 
A domestic dehumidifier is 300W ~ 1/2 hp allowing for drive inefficiencies. This will not be noticed at normal running power and with digital control the ECU takes care of engine idling speed.
 
Years ago when cars used carbs., and didn't have ECU's to control the engine revs, when you put on the air con at tickover the revs dropped so it must be using a bit of fuel. I wouldn't think a small compressor would use 10% as much power as propelling a ton of car at 70 mph.
 
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