MK5 Golf GTI

All Things Mk5 => Mk5 General Area => Topic started by: Ifti on May 30, 2009, 09:05:38 pm

Title: Air Con & Fuel.....
Post by: Ifti on May 30, 2009, 09:05:38 pm
A [stingy] mate of mine told me that he didnt use air con very much since it used fuel?

Is this correct? If so, how much fuel can having your air con switched on possibly use??
Title: Re: Air Con & Fuel.....
Post by: v2brett on May 30, 2009, 09:11:00 pm
it will use a bit more, not sure on the exact figure but i can remember JC on topgear saying a civic will do 6mpg less if the aircons on  :confused: :confused:      but i think the bigger the engine the less fuel it will use as its not struggling as much.   IMO its worth the fuel :driver:
Title: Re: Air Con & Fuel.....
Post by: bacillus on May 30, 2009, 09:39:27 pm
I recon it's about 2mpg difference on my car...
Title: Re: Air Con & Fuel.....
Post by: vwrascal on May 30, 2009, 10:56:18 pm
deffo worth the extra vpower wasteage today, I was cooler than zac efron holidaying in the antarctic  :chicken:
Title: Re: Air Con & Fuel.....
Post by: Ifti on May 31, 2009, 11:09:30 am
I really didnt think it used that much. I have had the air con on recently, and have been getting around 2-3mpg lower then usual, on a normal run. I actually thought somet was wrong initially, but forgot about having the air con switched on! lol
Title: Re: Air Con & Fuel.....
Post by: JonnyG on May 31, 2009, 11:16:52 am
There was a post a while ago with someone complaining about low mpg

They were advised to try not using AC, heated seats etc 

I think there mpg went up by about +3mpg as a result   :happy2:

Title: Re: Air Con & Fuel.....
Post by: Ifti on May 31, 2009, 01:13:23 pm
I thought heated seats and AC etc used battery power.
Why do they consume fuel as well?
Title: Re: Air Con & Fuel.....
Post by: BeezerDiesel on May 31, 2009, 01:19:24 pm
The aircon is a mechanical unit driven by a belt, this it makes drag on the engine. The aircon blower is electric as are the heated seats and rear window/mirrors etc. If these draw a charge constantly they will be draining the battery which in turn will need extra juice from the alternator. The alternator like the aircon compressor is also driven by the engine.
Combined, that's a wee bit of fuel usage that's not going to the wheels.

Unscientific answer I know but you get the drift.
Title: Re: Air Con & Fuel.....
Post by: Ifti on May 31, 2009, 01:25:53 pm
Yup I get it now, cheers  :wink:
Title: Re: Air Con & Fuel.....
Post by: winrya on May 31, 2009, 05:07:15 pm
But you also have to consider that the fuel consumption increases by 10% with the windows open  :happy2: 
Title: Re: Air Con & Fuel.....
Post by: bennylenny88 on May 31, 2009, 05:50:22 pm
my mpg goes down straight away  :rolleye:
Title: Re: Air Con & Fuel.....
Post by: neg on May 31, 2009, 06:00:04 pm
I read somewhere its like carrying another passenger - not the end of the world on days like today but when its not needed I always put mine on ECON.
Title: Re: Air Con & Fuel.....
Post by: Ifti on May 31, 2009, 06:04:38 pm
But you also have to consider that the fuel consumption increases by 10% with the windows open  :happy2: 

I always put the air con on rather then drive with the windows down at a higher speed - the wind noise does my head in!
However, like the above, I usually have it on ECON and only use air con when its a really hot day, or when I have the kids in the car.
Title: Re: Air Con & Fuel.....
Post by: Steve82 on May 31, 2009, 06:12:11 pm
But you also have to consider that the fuel consumption increases by 10% with the windows open  :happy2: 

I always put the air con on rather then drive with the windows down at a higher speed - the wind noise does my head in!
However, like the above, I usually have it on ECON and only use air con when its a really hot day, or when I have the kids in the car.

Same as myself, use it on Econ most of the time unless its a very hot day!
Title: Re: Air Con & Fuel.....
Post by: Jules86 on May 31, 2009, 06:16:17 pm
Aircon is better for fuel consumption than leaving the windows open  :happy2:

If anyone watches mythbusters they tested it thoroughly and aircon won  :wink:
Title: Re: Air Con & Fuel.....
Post by: vwrascal on May 31, 2009, 10:41:07 pm
wtf is econ?   :confused:
Title: Re: Air Con & Fuel.....
Post by: v2brett on May 31, 2009, 10:44:58 pm
Econ is the button you press to turn the aircon off,  its labelled different in some cars though   :happy2:
Title: Re: Air Con & Fuel.....
Post by: RedRobin on May 31, 2009, 10:57:30 pm
....

Econ = Economy

If you sit at traffic lights and switch the AirCon on and off you'll hear and see the engine revs change and therefore more fuel is being used.

Just cruising in town or similar, I'll have the sunshine roof open on days like today and have my rear windows down just an inch to release the cabin pressure.

I don't like the road noise of open windows either but I only use the AirCon (heater set to Lo) to chill the cabin in short periods.
Title: Re: Air Con & Fuel.....
Post by: Top Cat on May 31, 2009, 11:02:27 pm
I very rarely have the air-con running, and get the windows down whenever possible.

But i do have blueflame so i guess i am obliged to.  :evilgrin:
Title: Re: Air Con & Fuel.....
Post by: Ifti on June 01, 2009, 09:36:07 am
Econ is the button you press to turn the aircon off,  its labelled different in some cars though   :happy2:

I think its labelled AUTO in mine.

I do the same as RR - just switch the AC on when I need to in short periods, just to cool the cabin down a little, then its back to 'AUTO/ECON'!
Title: Re: Air Con & Fuel.....
Post by: docker1996 on June 01, 2009, 10:16:18 am
Don't you need to run the aircon regularly to keep the system in good condition?  :confused:
Title: Re: Air Con & Fuel.....
Post by: Ifti on June 01, 2009, 10:33:27 am
Don't you need to run the aircon regularly to keep the system in good condition?  :confused:

Dunno.
Never really use dthe aircon much in my previous car as the load it put on the engine felt immense! Really held the car back for some reason!
Never had any problems with it when I did need to use it though.......
Title: Re: Air Con & Fuel.....
Post by: neg on June 01, 2009, 10:34:34 am
Don't you need to run the aircon regularly to keep the system in good condition?  :confused:

yes its advised to - in winter if you run with the compressor off most the time its advised you give it a blast every so often to keep it in tip top condition - saying that with the british weather you probably find you need to use it on occastion in the winter.
Title: Re: Air Con & Fuel.....
Post by: neg on June 01, 2009, 10:50:22 am
Don't you need to run the aircon regularly to keep the system in good condition?  :confused:

Wife has one of the new MINI's when they first came out with Climate - that was a rubbish system and really drained the power.  The GTI although it does drain power is hardly noticable.

Dunno.
Never really use dthe aircon much in my previous car as the load it put on the engine felt immense! Really held the car back for some reason!
Never had any problems with it when I did need to use it though.......
Title: Re: Air Con & Fuel.....
Post by: RedRobin on June 01, 2009, 12:10:56 pm

I do the same as RR - just switch the AC on when I need to in short periods, just to cool the cabin down a little, then its back to 'AUTO/ECON'!


....Except that I go back to nothing set at all.

I just done a B-road drive this morning with sunshine roof open and all windows down only an inch - Plenty of tree cover and very fresh and comfortable with no aircon etc on at all.

I rarely use the heater in Winter either - Sometimes just to demist.
Title: Re: Air Con & Fuel.....
Post by: stealthwolf on June 01, 2009, 05:09:25 pm
In my old car (1.2 litre fiesta), the aircon could sap as much as 1/16th of the fuel in a long journey.

Haven't noticed any huge drops in mpg in the ED30.
Title: Re: Air Con & Fuel.....
Post by: v2brett on June 01, 2009, 11:37:13 pm
Don't you need to run the aircon regularly to keep the system in good condition?  :confused:
iirc the mk5 runs the aircon at a very low % even if not used to keep the system good,  id still say use it regulary though
Title: Re: Air Con & Fuel.....
Post by: ub7rm on June 02, 2009, 08:03:36 pm
Yes I think the A/C is still about 2% operational even when switched off just to keep the seals lubricated etc.

At town speeds its more economical to have the AC off and the windows open.  At higher speeds its more economical to have the AC on and the windows closed  :happy2:
Title: Re: Air Con & Fuel.....
Post by: pazz on June 02, 2009, 11:11:44 pm
I always try to remember to turn mine off "ECON" now and again. Not sure if this applies to MK5 Golf's but I've had an Aircon Compressor die on me before (on a 2001 Astra) and I'm pretty sure it was because I never used it. Supposedly have a tendency to seize up if not used.

Its also beneficial in preventing bacteria from building up on the evaporator. If you've ever noticed bad smells on Aircon systems its usually because somebody doesnt use it enough. Although I hear there can be other reasons like pollen filters etc.

Title: Re: Air Con & Fuel.....
Post by: ub7rm on June 03, 2009, 08:59:29 am
I always try to remember to turn mine off "ECON" now and again. Not sure if this applies to MK5 Golf's but I've had an Aircon Compressor die on me before (on a 2001 Astra) and I'm pretty sure it was because I never used it. Supposedly have a tendency to seize up if not used.


Yes the problem is is that the A/C gas also contains lubricant so if the AC isn't used the componets can seize up and rubber seals dry out and fail.  The mk5 golf addresses this by keeping the compressor turning at a very slow speed even when off so that the lubricant is constantly circulated.  This doesn't address the issue of smelly AC though so yeah its good to give it a regular blast and give it some anti bacterial treatment every so often.