Air Con Affecting Performance

[earpl]

dont take it to mr t, it aint a problem, theres that many variables that effect performance. some days my car feels a bit slow but then others (cold mornings etc it feels like WHOOO) everything effects performance, gradiants, road surface (friction), drag, air density (denser air is harder to push through) air temp, etc. if found that air con doesnt really make much of a difference as all it is, is a pump that runs on bearings. a small pump at that.

←

He's right. But you said denser air is harder to push through?? Cold air is more dense than hot or is it the other way around? Very cold air is wot an engine needs for perfermance, hense inter coolers etc.

Did you know that its better to fill up the tank on a cold morning because the petrol is denser. which equals more fuel for ya £££.

←

yeah but what i mean is the higher the density of the air the more wind resistance there is. hence aircraft are more efficiant at high altitudes.

[Al J]

Yes, I've also noticed that small engined cars respond better in cooler weather where the air is indeed, more dense. Warm air is less dense. Think birds (and hang-gliders!) riding thermals after launching off a cliff or hot air balloons.

OK, science bit over (at least the bit I'm comfortable with!).

Would cooler, denser air improve the air/fuel mix in each combustion chamber then? I've heard about ram air induction and the like so I'd imagine so but my ability under the bonnet extends to checking the oil and refilling the washer bottle.

[PaulT]

It could also be that you have the air-con on because it is hot, but the loss of power you are seeing is due to the hot air as well as the air-con.

I have the air-con on all the time in my Corolla, and in this heatwave I've noticed the loss of top end due to warm air going in rather than cooler stuff.

Of course, it's all relative and the car is still quite nippy, but doesn't really roar like it does when it's colder :D

Paul.

[GT4 BOOSTER]

for all those that dont know , when using air con , all windows must be kept closed , if a sunroof is fitted close it and pull the sun shade along , have the recirculating air switch set to recirc.have the fan on high and open all air vents.also set the temp to cold , be it normal or climate controlled.

[Al J]

for all those that dont know , when using air con , all windows must be kept closed , if a sunroof is fitted close it and pull the sun shade along , have the recirculating air switch set to recirc.have the fan on high and open all air vents.also set the temp to cold , be it normal or climate controlled.

←

Yes, this is my first car with air con (got it in March) and I found that trying to air condition the outside air wasn't very effective.

Well, it was hot and I wasn't thinking straight.

[alanbradley]

...but remember to turn the switch off recirculate when the temperature is down to a steady level otherwise you won't get enough fresh air into the car to keep you awake on long journeys

The difference in performance when the air is cooler is quite noticible in my car - I don't know if its the turbo/intercooler or what, but there is a noticible difference when overtaking.

As somebody's mentioned before, there will be a drop in economy when the aircon's on but, quite frankly, its no worse than you would get if you were to drive with your windows/sunroof open.

Alan

[GT4 BOOSTER]

once the air inside the car is at a likeable temp the aircon dont need to work so hard to keep it cool on recirc. the air outside maybe a degree or 2 hotter on the fresh air setting , therefore the aircon is constantly trying to cool it - make sence yet ?? opening windows lets in warm air as the sun roof visor lets in sun rays. call me a miser but thats the way it works to full effenceincy.

[earpl]

still turns the pump jast as much.

[GT4 BOOSTER]

i am no air con expert , its just advice i was given , i leave it to earpl who seems to know better.

[earpl]

just saying old mate, didn't mean to offend :)

[Demonic Angel]

for all those that dont know , when using air con , all windows must be kept closed , if a sunroof is fitted close it and pull the sun shade along , have the recirculating air switch set to recirc.have the fan on high and open all air vents.also set the temp to cold , be it normal or climate controlled.

←

Yeah - there have been occasions where I leave the sunroof open on tilt - say the works car park or when shes sat on the drive on a hot day - just to get a bit of air in the car - and then I forget its open and its left open when I'm driving and then I have to fiddle to close it!

Didnt know about pulling the sun shade along though - I always keep that open normally....

[GT4 BOOSTER]

non taken buddy - i'm a lover not a fighter.

demonic letting suns rays into the car through the sun roof warms the car and makes the air con work harder to get to its optimal temperature , its a bit like leaving the fridge door open and waiting for the food to chill.HENCE why imports with air con have no sun roof , and british cars with sunroof have no aircon . well that was years ago , now they have both seemingly. happy motoring yaris peeps.

[Al J]

Yes in the absence of an answer I'm leaning towards denser cool air causes a better air/fuel mix in the combustion chamber and so a btter burn (more oxygen). I'll Google it when I've got more time.

Oh and Em?...

Don't fiddle with your sunroof when driving!

[jonny_brin]

4000 rpm in 4th?? Why did you need to overtake at that speed?!?!

←

I was hoping this wouldn't come up... Maybe it was 3rd gear... :P

[Demonic Angel]

Yes in the absence of an answer I'm leaning towards denser cool air causes a better air/fuel mix in the combustion chamber and so a btter burn (more oxygen). I'll Google it when I've got more time.

Oh and Em?...

Don't fiddle with your sunroof when driving! 

←

lol I try not to fiddle with anything whilst I'm driving if I can help it!

[Blue84]

I thought it wasnt a good idea to use re-circ when the air con was on

what do most people do? circ on or off?

[Demonic Angel]

Mines on fresh air intake at the moment - but if I ever get stuck behind a smelly great big lorry or truck then I normally switch to re-circ!

[earpl]

I thought it wasnt a good idea to use re-circ when the air con was on 

what do most people do? circ on or off?

←

try re-circ with a pipe from the exhaust to the cabin nice & fresh :P

[ferrariboyuk]

I thought it wasnt a good idea to use re-circ when the air con was on 

what do most people do? circ on or off?

←

I normally use outside air but like demonic angel, i change to re-circulate if dusty old lorry is in front.

Air con will work better on re-circluate and you might find the air gets slightly colder on that setting than when you use outside air. On re-circluate, air that is going through the system has already cooled bu the air con.

I normally start on re-circluate, then move to outside air.

[Demonic Angel]

I thought it wasnt a good idea to use re-circ when the air con was on 

what do most people do? circ on or off?

←

try re-circ with a pipe from the exhaust to the cabin nice & fresh :P

←

Behave yourself Chris!

[Blue84]

try re-circ with a pipe from the exhaust to the cabin nice & fresh :P

←

LOL!!! Exhaust fume inhalation!?! No thanks

Fresh air intake it'll be then

Cheers

[earpl]

fresh fumes is all you get anyway.