"The problem with doing nothing is not knowing when you're finished" - Benjamin Franklin

Mike C · Senior Member

Open Windows V aircon

spida · Guru

Drove with all the windows down 3" - 6" in the heat, and sometimes with the driver's window right down, but finally gave up and shut them so I could use the aircon. NOW I have someone tell me a vehicle uses more fuel with the windows down than with running the aircon.

REALLY?

Am I suffering the heat, wind and noise for nothing when I could be cool and comfortable ..... Anyone have 'scientific' proof to back either theory confuse

neilnruth · Guru

My husband always says it uses more fuel to have air con on, but yes, why suffer when it is so hot? We travelled for three days last week in hot winds with windows down or partly down. Being the passenger, I had to put mine up as the sun was too hot without the protection of the tinted window. Today, it was wet and rain was pouring, and the wondscreen was fogging and I'm sure the petrol gauge was falling more quickly when I had to put air/con on to demist the windscreen. That's another point - why do we always have to use aircon now to demist? We used to be able to do it without before aircon. And sorry, I don't have any 'scientific' proof either.

turbopete · Senior Member

why be uncomfortable ,,,turn on the a/c drive to the river and jump in,,,,except in n/qld (big lizards)

turbopete · Senior Member

Hi neilruth was that when cars had quarter vents to direct air to the windscreen ?????

the rocket · Guru

a happy wife is a happy drive. airconditioning all the way for me in summer. cheers.

neilnruth · Guru

Maybe that was it Peter. See, sometimes new technology isn't always best. Those quarter vents worked real well.

vk6tnc · Guru

At highway speeds when aerodynamic drag becomes significant, windows up and AC on is more efficient.

After being stung by bees, twice on the neck and once on my arm, it's windows up for me !!!

Happywanderer · The Master

Don't have air con so don't have a choice. Love the drivers window open when driving in the sun.

Firefly · Guru

The first thing I test when buying a new car is the air con. biggrin biggrin

We use it all the time when its hot, towing or not. I like the comfort factor.

grandpabob · Senior Member

I read somewhere that up to 80kph drive with windows down above 80kph aircon on.

jimricho · Guru

Jeeze! the budget must be tight if one has to forego a bit of comfort just to save a dollar or two!

brickies · Guru

Spida why not do a test and prove it do 200 klm with a full tank of fuel with window down , fill it up again do the same with aircon on might get a surprise . But for me aircon on 365 days of the year life to short

Kiwi-as · Guru

Yes, read in 4x4 Mag. Under 70 to 80 windows down, and above have them up. Have travelled the last few months with them down, been doing it all wrong.

Mike C · Senior Member

Aircon on is the only way to go (unless the engine temp is climbing)
I vote for staying comfortable

vk6tnc · Guru

The Iveco van I drove at work had the AC on by default.

To turn it off you press a button called "ECON" !!!

KenK · Senior Member

I don't know how to turn the AC off in our car....but we have only had it for eight years. Only ever wind the windows down to fit the mirrors.
Ken

brickies · Guru

I think I know the real problem Spida can't find the knob for aircon

petengail · Guru

I asked my brother-in-law, a lifetime motor mechanic, and may I add a very good one, exactly this question. His reply was, along these lines. Given the extra wind drag with windows down, and the extra fuel used when using aircon. One counters the other and there is absolutely no difference. If you really want to save money wind the windows up, turn the aircon off and bake lol

-- Edited by petengail on Friday 12th of October 2012 11:50:14 AM

spida · Guru

well - yes. On a pension and at $3+ (2 litres ) per 100km increase x 20,000km then every little saving does help ashamed

spida · Guru

brickies wrote:
Spida why not do a test and prove it do 200 klm with a full tank of fuel with window down , fill it up again do the same with aircon on might get a surprise . But for me aircon on 365 days of the year life to short

I havent really used the aircon since WA but I do know my fuel jumped 2-3 Litres per 100km and over 20,00km at $1.50+ it makes a difference. Mind you I was just starting out and possibly a head wind north of Geraldton at that time.

jimricho · Guru

With all due respect I must say I find it hard to reconcile being able to afford a rig the size of the one in your avatar photo and not being able to afford to occasionally run the air con on a hot day!

2 litres / 100 k just to run the air con does seem a little high to me but I don't have sufficient information to challenge this.

Jim

Dougwe · Chief one feather

Aircon is great even in winter, have it on and the heater at same time, no more fogged up windows.

I am also of the belief that it is cheaper to have aircon on and windows closed than to have just windows open, remember not to have windows open when aircon is on though as the aircon will work too hard and pack it in.

turbopete · Senior Member

jimricho wrote:
With all due respect I must say I find it hard to reconcile being able to afford a rig the size of the one in your avatar photo and not being able to afford to occasionally run the air con on a hot day!

2 litres / 100 k just to run the air con does seem a little high to me but I don't have sufficient information to challenge this.

Jim

not only Pensioners,,,, of necessity must watch every dollar ,as i said in my earlier post if i was in no rush to get anywhere soon i would go park near water or find a shady spot or and go for swim

brickies · Guru

If I was that poor I would stay home

turbopete · Senior Member

brickies wrote:
If I was that poor I would stay home
t

I cant figure an answer for that statement,,, except to say thats lots of people poor or otherwise find enjoyment in their life by interacting with people on the track

spida · Guru

Well - 0nce again an interesting exercise asking a question. I did ask for 'scientific' comments and am getting irrelevant stuff about the size of my rig, my financial positions etc!
Sincere thanks to vk6tnc dougwe grandpabob and kiwi-as for giving me information that is of use.

Mike C · Senior Member

Hi Spida

If you want a technical analysis try this link

http://www.sae.org/events/aars/presentations/2004-hill.pdf

Duh · Guru

Slightly OT but with a Nissan Xtrail I had when long distance driving in extreme heat (40 degrees etc) after awhile my A/C would shut down.

I was told this was designed to stop your motor from cooking from overheating, I was told this by an A/C Fitter not connected to Nissan when I took it to him to look at, only happened once or twice on long runs when temp was extreme, eg; 400 kms run. Not much option then but to open the windows.........

-- Edited by Duh on Saturday 13th of October 2012 02:40:37 PM

Recoup · Guru

Hi Spida, a simple test, if you have a tacho in your car ( most new car do ) , start your car up and let it idle, it should run between 800 to 1000 RPM .

Switch on your Ac. and watch your tacho ,it will go up by 400 to 500 RPM. I am sure that with the Ac. on ,you will use more fuel.

Cheers Hans