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A/C & Fuel Consumption In Cars - Car Talk - Nairaland

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A/C & Fuel Consumption In Cars by Cruisez: 7:46am On Apr 30, 2013
I enjoy driving with my windows up and the A/C turned on. I usually don't pay attention to how it affects fuel consumption till a friend asked me what the fuel consumption is like when I don't turn on the A/C. I experimented for few days and discovered a negligible difference. let me point out that I avoid Lagos traffic like plaque. So I reported back my finding and this friend just won't believe me. He is a regular here so am asking for opinion from experts here on how A/C affects fuel consumption in cars.
Re: A/C & Fuel Consumption In Cars by Nobody: 8:41am On Apr 30, 2013
Aircon will affect fuel consumption more in slow traffic, more so if your compressor cycles on and off regularly (as it will if low on gas). The factor here is inertia, more energy is required on compressor start-up, and with an automobile travelling at low speeds, there's more drag (load) on the engine, requiring more energy to drive it.

At highway speeds, the effect of the compressor engaged on fuel consumption is negligible. Running at highway speeds with the aircon switched off, and the windows open will have a greater effect on fuel consumption, as open windows will alter the aerodynamics of the automobile, causing drag. The CD value (drag coefficient) can rise from lets say 0,28 to 0,43 with windows open.

It's worth noting though that modern automobile are switching from clutch-type (fixed displacement) compressors to variable displacement units, that have less drag, and consequently have less effect on fuel consumption.

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Re: A/C & Fuel Consumption In Cars by lonelydora: 3:05pm On May 03, 2013
Siena: Aircon will affect fuel consumption more in slow traffic, more so if your compressor cycles on and off regularly (as it will if low on gas). The factor here is inertia, more energy is required on compressor start-up, and with an automobile travelling at low speeds, there's more drag (load) on the engine, requiring more energy to drive it.

At highway speeds, the effect of the compressor engaged on fuel consumption is negligible. Running at highway speeds with the aircon switched off, and the windows open will have a greater effect on fuel consumption, as open windows will alter the aerodynamics of the automobile, causing drag. The CD value (drag coefficient) can rise from lets say 0,28 to 0,43 with windows open.


It's worth noting though that modern automobile are switching from clutch-type (fixed displacement) compressors to variable displacement units, that have less drag, and consequently have less effect on fuel consumption.
U should be working for automobile companies and not Nairaland.

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Re: A/C & Fuel Consumption In Cars by arcis: 3:25pm On May 03, 2013
Siena: Aircon will affect fuel consumption more in slow traffic, more so if your compressor cycles on and off regularly (as it will if low on gas). The factor here is inertia, more energy is required on compressor start-up, and with an automobile travelling at low speeds, there's more drag (load) on the engine, requiring more energy to drive it.

At highway speeds, the effect of the compressor engaged on fuel consumption is negligible. Running at highway speeds with the aircon switched off, and the windows open will have a greater effect on fuel consumption, as open windows will alter the aerodynamics of the automobile, causing drag. The CD value (drag coefficient) can rise from lets say 0,28 to 0,43 with windows open.

It's worth noting though that modern automobile are switching from clutch-type (fixed displacement) compressors to variable displacement units, that have less drag, and consequently have less effect on fuel consumption.

Auto Siena, u are the best, just believe it!!!! shocked shocked shocked shocked shocked shocked shocked shocked shocked

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Re: A/C & Fuel Consumption In Cars by Abiolanzy(m): 5:50pm On May 03, 2013
@siena i don't understand. plz simplify

TNKS

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Re: A/C & Fuel Consumption In Cars by Cruisez: 2:19pm On May 04, 2013
Siena: Aircon will affect fuel consumption more in slow traffic, more so if your compressor cycles on and off regularly (as it will if low on gas). The factor here is inertia, more energy is required on compressor start-up, and with an automobile travelling at low speeds, there's more drag (load) on the engine, requiring more energy to drive it.

At highway speeds, the effect of the compressor engaged on fuel consumption is negligible. Running at highway speeds with the aircon switched off, and the windows open will have a greater effect on fuel consumption, as open windows will alter the aerodynamics of the automobile, causing drag. The CD value (drag coefficient) can rise from lets say 0,28 to 0,43 with windows open.

It's worth noting though that modern automobile are switching from clutch-type (fixed displacement) compressors to variable displacement units, that have less drag, and consequently have less effect on fuel consumption.

Siena what else can make compressor cycle on and off often apart from low gas? I observed mine today and noticed it cycled off and on often. I have not driven the car for over 2 hours when I carried out the observation. How did I carry this out? I just looked at a see through glass and observed the rotation of a metal like rod and the resultant bubble. I recently added gas.
Re: A/C & Fuel Consumption In Cars by aflag: 10:48am On May 05, 2013
good a.m siena, i only feel the chilidity of my aircon when im on top speed. Wheneva im in the traffic i need to roll down the glass cos its usually as hot as hell. I consulted an auto tech and he told me dat the compressor is weak and thats why it önly gets cold when on top speed. I told him i was going to get back at him after cönsulting wit my auto gurus on NL.
Anticipating some pro advice.
Re: A/C & Fuel Consumption In Cars by alphaconde(m): 8:55pm On May 05, 2013
I used an audi a6 v6, the ac and without ac consumption is same. But on highways same fuel covers more distance. But seriously my ac doesn't make my car consume more fuel. I once told a friend that if I drive without ac den am loosing out
Re: A/C & Fuel Consumption In Cars by dd22: 9:32am On May 06, 2013
Thanks for your piece of advise. It is professional and I hope it will enlighten all car users to beware of roadside technicians whose trademark is guessing. One Love
Re: A/C & Fuel Consumption In Cars by cretin: 2:21pm On May 06, 2013
cycling on and off is normal......it depends on the tempreture setting...even the house a/c cycles on n off depending on the set and ambient temp.
Re: A/C & Fuel Consumption In Cars by Emperoh(m): 3:50pm On May 06, 2013
aflag: good a.m siena, i only feel the chilidity of my aircon when im on top speed. Wheneva im in the traffic i need to roll down the glass cos its usually as hot as hell. I consulted an auto tech and he told me dat the compressor is weak and thats why it önly gets cold when on top speed. I told him i was going to get back at him after cönsulting wit my auto gurus on NL.
Anticipating some pro advice.

Ensure that your cabin filter; located under the glove compartment, is free of dust.
This is a culprit. Secondly, check that your condenser is not being blocked. Blockage will eventually damage your AC compressor.

If these two check out, then you might have a weak compressor.
Re: A/C & Fuel Consumption In Cars by aflag: 7:30pm On May 06, 2013
thank u sir!
Re: A/C & Fuel Consumption In Cars by ib4babes(m): 1:58pm On May 28, 2013
Emperoh:

Ensure that your cabin filter; located under the glove compartment, is free of dust.
This is a culprit. Secondly, check that your condenser is not being blocked. Blockage will eventually damage your AC compressor.

If these two check out, then you might have a weak compressor.
with low gas in your system, you'll be having this experience too. So try toping up your gas.
Re: A/C & Fuel Consumption In Cars by Nobody: 2:18pm On May 28, 2013
good day house,

please what could be the problem of my Honda accord 2.0 engine,it uses 10L for 54KM on highway and 10L for 22KM within city,the above calculations are with AC on.OR is it normal
I will appreciate helpful advice.
thanks
Re: A/C & Fuel Consumption In Cars by Ikenna351(m): 2:39pm On May 28, 2013
iykedenis: good day house,

please what could be the problem of my Honda accord 2.0 engine,it uses 10L for 54KM on highway and 10L for 22KM within city,the above calculations are with AC on.OR is it normal
I will appreciate helpful advice.
thanks

In another words, your 2.0L car average 20 L/100km on highway and average 40 L/100km in the city. No, its far from being normal. Its a disaster. Are you running a refinery in your fuel tank, such that you didnt notice how thirsty your car has been?

My 3.0 D9 average 7 L/100km on highway/expressway, while my 2.8 PRV average 10L/100km. Go figure.

Your car is having serious injection issue.

Ikenna.
Re: A/C & Fuel Consumption In Cars by Nobody: 2:52pm On May 28, 2013
What do i do,
please i need help here.
Re: A/C & Fuel Consumption In Cars by Kx: 2:59pm On May 28, 2013
@ Siena and Ikkena.
Can one safely summarise that oga Siena means:
" Use ac while u are "on speed" but off if while u are in "lagos" traffic?
Re: A/C & Fuel Consumption In Cars by Nobody: 3:14pm On May 28, 2013
am still waiting for advice for my refinery (Car)..

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Re: A/C & Fuel Consumption In Cars by Ikenna351(m): 4:13pm On May 28, 2013
iykedenis: am still waiting for advice for my refinery (Car)..

Lol! @ refinery.

Anyway, whats the model year of your Accord? Petrol or Diesel?

Ikenna.
Re: A/C & Fuel Consumption In Cars by Nobody: 4:20pm On May 28, 2013
its honda accord 2.0 engine i4,popularly known as bullet.. its a petrol engine..1997 or 1998 not too sure of that.
Re: A/C & Fuel Consumption In Cars by Ikenna351(m): 4:23pm On May 28, 2013
iykedenis: its honda accord 2.0 engine i4,popularly known as bullet.. its a petrol engine..1997 or 1998 not too sure of that.

Then its OBD II compliant. Find where you can scan the car and pull error codes to know which component(s) that have failed, making the car to be running that rich.

Ikenna.
Re: A/C & Fuel Consumption In Cars by Nobody: 4:25pm On May 28, 2013
ok sir,i will do just that..then i will report back
Re: A/C & Fuel Consumption In Cars by Nobody: 9:26am On Nov 05, 2013
Good morning everybody,

I am happy to come back here to say how this place has helped me to manage my daily affairs,though am not a known contributor,i enjoy reading and observing and correcting myself with useful advice.
I also want to thank ikenna and co,as regards my complain here,i was not able to get a scanner,but i finally saw a place in zuba,they said he is an specialist in injection systems.
when he saw the car,he changed the oxygen sensor,there is a switch from the ecu to the throttle body, he also connected because that switch was off,and i never noticed.immediately he did these things ,i notice my engine sound change.the check engine light went off immediately.
As am talking to you now,i started the test with 20L,i went to wuse from kubwa,came back,drove around kubwa for days,finally i check my meter,i covered 201km,with first sign of reserve light showing,then i refueled. for another test.i was shocked....mind u., i use AC always.i tell you every morning i start the car,after 1 min to 2 mins,you will see steams coming out like when i bought the car new.the movement is now super on speed.
BUt i will also want to knw if there is anything i need to do in other enjoy these fuel economy well or is it normal like this.

Secondly,i also need help in these area,Normally, my car stays at 1,without ac,but with ac b/w 1 and 800..but i noticed that sometimes ,with ac it will fall as low as 500,and the engine will be shaking,some times it will remain at 1 with ac on.my mind is telling me its not normal..though outside this,i am enjoying the car now. like brand new.this case in like once in while.but i still need to check it.

please Oga ikenna and co ,i need help in this area.

thanks.
Re: A/C & Fuel Consumption In Cars by Nobody: 2:21pm On Nov 07, 2013
i did 198km for 20L this time around.Only within kubwa and bwari.with Ac on as usual.
As for the engine shaking,i found out that once i put on the ac,and press my gas pedal ,there is this high grinding sound around the alternator belt..though i dont knw the exact belt.my mechanic adjusted it and tuned the engine to normal .I think for now no more sound and no more vibrations when ac is on.am still watching it.

plz Oga ikenna and co,Una travel..if you are within internet link,Abeg help contribute to this ,so that i will know if everything is alrite.

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