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Air con question


Bit of a weird question - using air con does it use more fuel in your car?

My mate said No it doesnt its just a myth, it use to in older cars.

Im unsure, anyone have any info?
  Polo + Micra

yeah it does because it puts extra load on the engine.

"energy cannot be created or destroyed, it can only be converted"


  Pink/Blue 182

the dealer told me that modern cars use more fuel with the windows down than they do with the Air con on.........but i did say Dealer
  Pink & Blue 182, JDM DC2

technically using the air con will use more fuel as its extra strain on the engine to run it - therefore using more fuel.

Driving with windows down will also use more fuel as it affects the aerodynamics of the vehicle but only noticable really at high speeds - the Clio is pretty sh*t aerodynamic brick so I wouldnt worry too much about it.
  133/225/CLS AMG

Does seem to use more fuel whether or not that is more than having your windows down I dont know.

I dont like the fact that it noticeably reduces acceleration!! Especially in smaller engines.


  Audi TT Stronic

Quote: Originally posted by Adamf on 23 May 2005
My mate leaves his on "auto" all the time. Although it is a TDi130 and never drops below 50mpg LOL!

Dont confuse auto with the air-con actually being on. I leave mine on auto and the air-con only comes on if its really hot.


  Audi TT Stronic

Quote: Originally posted by AlexJMills on 23 May 2005
I dont like the fact that it noticeably reduces acceleration!! Especially in smaller engines.

On my 172 I cant notice it.
  133/225/CLS AMG

I tend not to use my ac more due to the responsiveness on my 172 being reduced. I dont like the thought of losing power but using more fuel either lol.


ClioSport Club Member

In my old Pug 306 D, if you put the aircon on when trickling along on tickover in traffic, it was like youd just stabbed at the brakes. Then when the engine woke up and realised it was loaded by the compressor, it would fuel more to compensate.

Made me realise just how much of a load on an engine an aircon compressor actually is.

I noticed a difference in performance on the 172s with Climate rather than my own with just aircon.

Id agree it uses more petrol, hence why I hardly ever use it now. Need to let it blow occasionally or the build up of bacteria will make you ill!

Yeah true, I tend to leave mine on for a quick blast as the cold tends to come through for ages after anyway.

Thanks for the replies btw. I can tell him that it does use fuel and that he is talking out of is ass.


Yes A/C does use a little more fuel, and yes older vehicles used even more.. Compressors now are pretty efficient and it is not that noticable..

Not running the A/C regularly can risk the Pipe seals drying out and leaking or at worse, causing the compressor to be starved of oil and therefore running the risk of it seizing. So it should be run at minimum once a week for 20mins or so.. Not running the A/C also allows bacteria growth on the Evaporator, that is why you get that "smelly Sock" odour if it hasnt been used for a while.

Remember also that A/C is not only useful during the hot months.. It acts as a dehumidifier, and that is why in winter when the A/C is switched on, the inside of the windscreen clears of condensation/moisture very quickly..

In reality you should run it all the time.. 1: to protect the working parts. 2: to keep you cool and moisture free..