Fuel Consumption & Air Con/Climate Control

[Chequered Flag Racing]

Anyone link me to official or independant data for mpg getting worse if you use air con, climate control?

Her new Jazz has air con and she won't use it due to Press/TV articles re increased fuel usage. She even turns it of in the Passat which is climate control. Needs to be on as without it there's no fan to circulate air in the cabin and I can see no extra being used due to using it.

just emailed Honda UK asking for data

[Big G]

well it's driven off a pump which is run off the engine... so the short answer is yes it effects MPG since the engine has to create the BHP to turn the AC pump, but when not in use it disengages the pump so it becomes an expensive pulley.

[Chequered Flag Racing]

Thanks Big G, but I knew that but there will be some that don't

what I'm after is data so that I show her by how much and allay any fears she has that it drinks fuel

[DCM]

It is swings and round-a-bouts.... not sure about the climate control, but with A/C, if your driving round with the windows open, that affects MPG as much as running round with the windows up and A/C on, thats how I have found it.

Also, A/C is great for the winter, to demist the windows to.

[Bungleaio]

Mythbusters did an experiment to test this, apparently above 50mph it's more efficient to have the windows up and AC on, below this it's the other way round.

It's doesn't make a massive difference either way though especially in a Jazz, my parents get 40+ mpg out of theirs.

There are bigger things to worry about than achieving a couple of extra mpg!

[Chequered Flag Racing]

Originally Posted by Bungleaio

There are bigger things to worry about than achieving a couple of extra mpg!

saving money in our lasses case

but then I spent 11k on the car for her

still looking for a link to data though that shows it in real time

[bodgit]

My wife has a jazz but the aircon needs regassing so is off at the moment but she averages 44mpg if thats any help. Thats urban driving mainly.
I tried the mpg with it both on and off in my cmax 2.0 lt diesel. To be honest I never noticed any difference whatever type of driving I did. I get 44-45mpg normal everyday driving with it on and if I go see my lad in Cardiff I get 55-56mpg over 300 miles with it on.
At the end of the day its for your comfort use it. Nothing worse than a stufffy hot car for distracting your driving and it keeps the windscreen mist free.

[bigred5765]

http://www.airconco.com/news/tag/fuel-consumption

you'll waste more fuel driving with the windows open, air con uses 8-10% extra

[Chrislong]

It depends on the car. A big torquey diesel will hardly be effected by it, but a weaker 1.2 1.4 petrol will be under more strain. I found my 1.4 Fiesta was effected by approx 10% by Aircon, but my 2.2 TDCI Mondeo isn't by anything I notice.

If you want it on, put it on, the difference it makes even at 10% can be also as much lost by an unserviced car, heavier right foot, poor clutch control or even sitting with tickover on when no need to.

You know the recharge thing? Kwik fit or who-ever say they'll recharge the aircon and make it work better or else its free, this is always the case as I am informed new cars aircon is never completely filled - hence always an improvement on a recharge/fill!

[Jamie.T]

Ive looked into mpg figures for a while now, and there are much bigger variables besides air con. For example tyre pressures, tyre make/model and compound can make a much bigger difference than having your air con on or off.

As has been previously stated a smaller petrol engine with little torque will be effected a lot more than a bigger diesel engine. Average figures show that air con takes approx 2-4bhp, which on a large 150bhp diesel engine is tiny, but a small fiesta 1.4 with just 70bhp is much bigger.

Tyres is the biggest varibale, but you have to weigh up the cost of the more economical tyre against a cheaper brand. Is paying twice the price for a new michelin going to warrant the small saving in mpg.

I would personally just enjoy the car, switch on the air con without worrying how much its really costing. The saving is so small your not really going to notice it unless your a rep doing 80k+ a year.

Jamie......

[bodgit]

If she,s still not sure sell the jazz and get a £2k car with air con and tell her she,s saved £9k

[purpletimbo]

I run a mitsubishi diesel taxi, 1000 miles one week no aircon, too damn cold in May?? 48MPG average
1000 miles week after races on stuck in traffic a lot, 47MPG average, but I am sometimes cagy and flick it off if the car is cool enough and I am going to be stood ticking ages.
It is a 1.9 turbo 120 HP in a 995Kg car mind you, so a little overpowered to start with.

[jim76]

Originally Posted by Chequered Flag Racing

Needs to be on as without it there's no fan to circulate air in the cabi

are you sure about that?
My old focus had climate control, and there was a button to deactivate the aircon element of this so that you could just have the fans blowing with out the cooling/heating element.

[Big G]

the average MPG's you talk about. are they want your car computer says or are you running the tank down from full and dividing the miles achieved by the capacity of the tank?

My mk4 golf can say 70mpg on the dash, but the most I've managed out of a single tank is 620 miles. tank is 12 gals which I work out to be 52mpg or close enough

also I quietly chuckle at those with england flags on their cars running around with more drag

[Chrislong]

Originally Posted by Big G

also I quietly chuckle at those with england flags on their cars running around with more drag

Also, they're BANNED aren't they? ridiculous, the world is going mad.

[Big G]

if they are a fair few round my place don't know that. I saw some for sale the other day

[bodgit]

They probably wont be up for long anyway

[steelie600]

APARENTLY, the foreigners are moaning that it is in conflict of their human rights, yes thats right. In our OWN country we cant be patriotic, due to visitors, lallygaggers (is that a word??) and illegal immigrants!!! Guess what ive done, oh yes St Georges cross on me car front window on the house and on the chimney!!! Feck em I say, its our country NOT THEIRS if they dont like it Ill help em pack myself!!

[showtime]

the amount of power your aircon will use entirely depends on which kind of AC it is. generally most small engined/lower spec cars have variable venturi type which utilises a compressor with a clutched pulley that kicks in or out & & because when its "In" the compressor is working at full whack & you can feel that extra load on the engine!
the other kind is fixed orifice that generally is active all the time. the pump is constantly engaged but it has a variable swash plate inside so if you dont need a lot of pressure it doesn't push a lot of pressure so load on the engine is reduced a lot of the time

to put it in basic terms say we need 50% worth of cooling
the fisrt system will have its compressor kicking in & out but working at 100% when active for the approximately half the time

the climate control type system will just have the compressor working at 50% of its capacity for 100% of the time

the climate controlled car will be a lot smoother & the temperature should stay relatively constant
the std AC car will get warm then clonk the compressor will kick in, the fans will blow cold for a while cooling the car then the compressor will disengage & cabin temperatures will start creeping up again! and so it goes on.......................

personally mines never ever been turned off, its active all year round as AC also dehumidifies the air which demists you quicker & helps your windows stay clearer if you have a car full of damp people etc

heres something to consider!
any AC system is kept gas tight by rubber seals. these rubber seals are kept healthy & moist by oil in the refrigerant which coats them as the system is used. if you leave your AC switched off for long periods of time these seals can & do very often dry out & all the refrigerant gas escapes!
every year during the first hot week we are mobbed by customers complaining " my AC's not working, it worked fine when i used it last summer" etc

so in their quest to save money how does £100 to recharge the system sound or another way is in their quest to save a rainforest by not turning it on because of emissions has led to a leak of R134a refrigerant which is a known greenhouse gas with very severe penaltys for accidental discharge!
The 1997 Kyoto Protocol puts R-134a as one of the 6 greenhouse gases that must be handled with extreme care.


anyway the morale of the story is if you got it you may as well use it

[purpletimbo]

Just reread the thread, if you were asking about my taxi fuel consumption readings, the dash has been stuck on 41.9 average for 2 years, but I work it out over 1000 miles, full tank to full tank.
Couple of useful online free calculators about, add in pemce per litre mileage and cost, give you either pence per mile, which is my main financial concern, or mpg in old money, that we all can work out in the real world, not K/l