Does airconditioning effect my fuel consumption?

Archi on 10/01/2014 - 11:21

I have been lead to believe that having the air conditioning on all the time effect the fuel usage of the car,

I have read that at high speeds having the windows down will increase resistance and drag and therefore also effecting your fuel consumption.

so at low speeds maybe under 60km/hour having the windows down
at speeds above 60km/hour its better to have the air conditioning on.
makes for better fuel economy.

what is everyone's thought on this. ?

doesn't obviously factor in the really hot days where you wouldn't care about fuel consumption and staying cool would be the absolute priority

and doesn't factor in the times when you are stationary

Automotive

Comments

  • Cyphar on 10/01/2014 - 11:29
    +6

    When your aircon is on and kicks in (Once the compressor starts up), if you look at your RPM odometer, you'll see it jump up as the compressor needs the engine to run to work. If it's forcing your engine to be used more to power it, it will use more fuel as a result.

      • Scrooge McDuck on 10/01/2014 - 16:03

        He's probably talking about an automatic transmission when the torque converter isn't engaged.

        • pmupsinep on 12/01/2014 - 15:08
          +2

          Pretty sure he'd be talking about the RPM when stationary (and probably in neutral). Once you're driving the RPM would not change in a manual and in an auto you would probably not see any difference.

        • John Dough on 16/01/2014 - 09:27

          Although RPM is linked to road speed in a manual transmission and in most Post say 90's Autos are lock up torque convertors, this is about LOAD on the engine.

          Turning an AC on whilst driving is like going up a hill. The RPM and road speed do not change, BUT the engine works harder by burning more fuel due to the LOAD on it.

          Of course there are many many other factors but if you add load to a car, it will burn more fuel - simple.

        • MATTDAMON on 16/01/2014 - 14:24

          Some vehicles do increase idle engine speed when the AC is engaged, my Mitsubishi challenger comes to mind.

        • John Dough on 16/01/2014 - 22:58

          Yes agree at Idle rpm often fluctuates as load is applied and the cars ECU compensates.

      • _Bruce_ on 10/01/2014 - 16:13
        +4

        In addition to Scrooge McDuck's comment, an auto may even change gears when the AC is on.

    • airzone on 14/01/2014 - 00:21
      +1

      This effect is normally caused by a solenoid on the inlet that will allow a small amount of extra air to bypass the throttle to give the engine a bit more kick when the A/C compressor activates while the car is idling.

      But yes, the compressor requires horsepower to run, and the engine burns fuel to provide for it.

  • retiredfeline on 10/01/2014 - 11:30
    +18

    http://www.environment.gov.au/settlements/transport/fuelguid…

    recommends using air conditioning above 80 km/h due to air drag. Obviously this depends on the car and other factors.

    BTW, it's affect.

    • strangeloops66 on 10/01/2014 - 11:38
      +3

      Mythbusters suggested* 55mph (~90kph), but they used a 4WD (which would indicate a lower speed, not a higher speed, as appropriate for windows up, so I give up!).

      *Series 2, episode 22

      • hellbound on 10/01/2014 - 12:27
        +4

        They revisited it in a later episode and acknowledged that it does depend on both the car design and the speed travelling.
        I use 80km/h as my guide, below that use windows, above that aircon, but that's more to avoid that buffeting effect that annoys me

      • ProjectZero on 10/01/2014 - 12:28

        I was gonna quote them too lol

    • diddy50 on 11/01/2014 - 13:59
      +4

      The effects of the air con affects the car

    • Dollarsandsense on 13/01/2014 - 23:53
      +1

      I have been toying with the button which circulates air in the car rather than taking new air in. Today I opened the windows until the car dropped to outside temp. Closed the windows, turned on air con until I was at a happy temp and then pressed the button to keep the cold air circulating without dragging in new warm air which it would need to cool. And then I turned the air con off and let the air continue circulating.

      • Tuba on 14/01/2014 - 00:08
        +2

        You do realise the AC works quicker and more efficiently using the 'recirculate' setting, not fresh air? It also gets much colder using recirc. I ask as your description suggests you run the ac with it set to 'fresh'.

        • Dollarsandsense on 14/01/2014 - 23:05

          Yeah, I think it's my idea that the air will be fresher in the car if converted to cold on the way in not turning hot air in the car into cold. Now that I type it this idea sounds stupid so I'll just go straight for the recirculation!

        • Tuba on 14/01/2014 - 23:14

          Not really. I do it too sometimes as I dont need it so cold. But if the temp outside is too hot, I will use recirc all the time. Again if not ridiculously hot, sometimes I also open the sunroof with the ac running too. The cold air falls so it mostly seems to stay in the car, and the pop up shield thingy stops outside air blasting inside.

          I too like fresh air, and cold.

        • Dollarsandsense on 17/01/2014 - 00:15

          I have been toying with running aircon on recirculation until cold enough and then turning the air con off and letting the cold air continue to recirculate. Probably only need to cover every third minute of aircon this way :-) company pays for fuel so call me a considerate employee!

        • Tuba on 17/01/2014 - 00:41

          company pays for fuel

          Your reluctance to rape the crap out of that offer is not in the spirit of OzBargain.

          Good day to you Sir!!

  • _Bruce_ on 10/01/2014 - 12:00
    +5

    Yes AC uses lots of petrol. If you have climate control don't just set it to 20 and leave it, set it to low enough to be comfortable, every extra degree takes even more energy. If you have a fixed on/off button don't leave it on, turn in off once you are comfortable.

    Also mixing AC and open windows doesn't work well, if your car is cooler than outside openning the windows just lets the heat back in. On the other hand on a hot day openning the windows first then closing them and turning the AC on will save petrol.

    • MATTDAMON on 11/01/2014 - 10:35
      -2

      Its not that much more, in the region of around 1L per hour more or so for most vehicles. I wouldnt personally be worrying much much about it, is your comfort worth that little money?

      I leave mine on all the time, never turn it off, all i do is ensure during the colder months that it drys out regularly otherwise it will start to smell.

      The one in my truck (its an electric unit located ontop of the cab) is also run 24/7, its far far more powerful then the average car AC though, and sucks down some serious electricity even on 24v.

      • _Bruce_ on 11/01/2014 - 16:08

        sucks down some serious electricity even on 24v.

        The power is measured in watts, 24V just means it needs more current to do the same job.

      • HerpDerp on 13/01/2014 - 19:06
        +2

        How do you dry it out regularly during the colder months Copie?

        • MATTDAMON on 14/01/2014 - 19:11

          Run it on heat for several hours. The AC portion still works on my system since it doesnt use engine coolant for the heater core, its reverse cycle almost exactly the same as what you find at home.

        • John Dough on 16/01/2014 - 09:31

          In this case, the trucks alternator will be under more load to provide the current needed to power the AC, therefore using more fuel. As trucks are usually a diesel big torque monster this load would be barely noticeable.

    • pmupsinep on 12/01/2014 - 15:02
      -2

      Car air conditioners don't work like house air cons. The compressor will still be engaged regardless of what temperature you set, it will simply increase or decrease the hot air from the heater being mixed into output.

      • _Bruce_ on 12/01/2014 - 15:29
        +1

        I assume you are referring to my advice for climate control? Many modern cars with climate control will turn off the compressor. Some will even scale down the compressor load.

        • pmupsinep on 12/01/2014 - 17:15
          +1

          Yes. Which ones?

        • _Bruce_ on 12/01/2014 - 19:37

          My 2004 Volvo does this (on/off, not load scale).

        • John Dough on 16/01/2014 - 09:35
          -1

          Absolutely cars AC will vary load and will switch on and off based on your in car settings. If you open the engine bay with the AC running (and the car temp inside the car is at its climate controlled temp) you will hear a click. This is the AC compressor engaging and disengaging.

          Every car with an AC drives the accessory belt that loops through the AC compressor regardless if the AC is on or not. Turn the AC on, and the electromagnetic solenoid engages and the compressor is started. This is the point where more fuel is instantly used to drive the compressor.

      • zeomega on 12/01/2014 - 21:49

        The REALLY old tech does it that way. Think early 1990s.

      • chiefbodge on 14/01/2014 - 17:16
        +3

        The opposite is actually the case in pretty much every single automotive compressor I have ever seen (and I have seen quite a few).

        The compressor is usually driven by a belt (often the main belt that drives the alternator etc..) while it's true that the pulley on the compressor is constantly spinning there is a solenoid/clutch system which is electronically engaged / disengaged when you press the "AC" button on your dash. When the AC is off in your car the AC compressor pulley is freewheeling and not actually driving the compressor.

        All climate control does is automates the process of engaging/disengaging the compressor based on cabin temperature.

      • cvas on 14/01/2014 - 17:23

        Nope they have an electromagnetic clutch which disengages/engages the compressor. The compressor is not "permanently" on

  • cloudy on 10/01/2014 - 13:54
    -3

    Answer is, more than you think!

  • Storm on 10/01/2014 - 14:58
    -4

    I have a Prius so it doesn't affect me as much :) The electric side of the motor handles the aircon most of the time (and it recharges as you drive anyway).

    • Austin 316 on 10/01/2014 - 15:15
      +8

      You shouldn't really be commenting here :)

    • _Bruce_ on 10/01/2014 - 15:15
      +10

      It affects you exactly as much. The engery has to come from somewhere, either the petrol engine directly, or from the battery which then means the petrol engine needs to start sooner to recharge.

      Potentially due to losses in storage/transmition it actually affects you more.

      • PresidentClinton on 12/01/2014 - 01:46
        +2

        That's why Storm's a prius owner.

        • _Bruce_ on 12/01/2014 - 11:45
          +3

          Because they are powered by magic pixie dust?

    • hubertlam on 12/01/2014 - 21:58

      Our two Camry hybrids does show a dramatic increase in fuel consumption when AC is used at lower speeds.

      The electric vehicle mode takes longer to kick in as the AC requires the power from somewhere — whether battery or engine.

      Also, to save fuel, we match the temperature of the inside of the car to the temperature outside as long as it's between 19 - 24 degrees. If the outside temp is > 24 degrees, we leave it at 24. If it's lower than 19 (e.g. winter rainy day) we leave it at 19. However, on the newer Camry hybrid there are full sized front weathershields, thereby avoiding the AC entirely on winter rainy days unless it's absolutely freezing outside and a bit of heating is needed.

      At 80+km/h we always close the windows. However, if weather permitting the AC may still not be used as we then let the air in from outside, but that is quite rare. Inside tunnels the AC always goes on regardless.

      If driving alone without passengers, there is a far less likelihood I'd use AC as well.

  • Scrooge McDuck on 10/01/2014 - 16:06
    +3

    Turn your AC on when braking or coasting and back off when you apply the throttle again. That way it should only take power from the car's kinetic energy which you're wasting anyway.

    • _Bruce_ on 10/01/2014 - 16:14
      -2

      This logic is flawed. It only works in specific circumstances to help with engine breaking, in most circumstances it does not help.

      • Scrooge McDuck on 10/01/2014 - 16:37

        When braking or coasting you are engine braking. Unless you ride the clutch which you shouldn't.

        • _Bruce_ on 10/01/2014 - 18:41
          -2

          Coasting yes, braking no (mostly). And this will increase the amount of engine breaking, which may or may not be what you want.

        • strangeloops66 on 11/01/2014 - 01:09
          +8

          No way I want a broken engine ;)

        • zeomega on 12/01/2014 - 21:51

          Explain how would engine braking kill your engine?

        • pmupsinep on 13/01/2014 - 19:52

          If you break your engine, you have killed it.

    • John Dough on 16/01/2014 - 09:37

      I thought I was the only one that did this. True Ozbargain style!

      • John Dough on 16/01/2014 - 23:08

        If you want to get really frugal, you can manually minimise fuel consumption;

        1. Turn the ac off at lights/stops and when you are about to accelerate.

        2. Turn the ac back on only once at a constant cruising speed or de-accelerating.

        3. Turn the ac off when overtaking (most modern cars will automatically disengage the ac under a kick down scenario or when 100% throttle is applied - not recommended if you are trying to save fuel!)

        4. Turn off the ac when arriving at a hill or a road scenario that will require more throttle input than normal as the ac will exponentially raise the percentage of normal fuel consumption because of the excess load of the ac, only turn it on when you are back on light throttle.

        Of course these 'rules' will apply more to some cars than others, particularly older, smaller 4cyl cars that are low in the tourque/power department.

  • peterw1 on 10/01/2014 - 17:09

    yes (thanks cleaseau!)

  • Amaris on 10/01/2014 - 18:01

    The energy needed to drive the A/C compressor has to come from somewhere….usually petrol/ diesel!

  • maybeamacy on 11/01/2014 - 00:39
    -1

    I like to use my car to watch DVD's in with the aircon on for about 30mins during a lunch break. Is that really bad for fuel or only a few dollars?

    • _Bruce_ on 11/01/2014 - 10:09

      It's bad for fuel and the environment. It will be 'only' a few dollars, but that is a matter of perspective.

      • Grent on 11/01/2014 - 12:10
        +1

        Bad for the environment compared to using a home residential aircon running at several kW off coal power through the grid?

        • retiredfeline on 11/01/2014 - 12:11

          Worse. Petrol costs more.

        • _Bruce_ on 11/01/2014 - 16:09
          +1

          Much worse. Petrol engines are at most 30% efficient.

        • outlander on 12/01/2014 - 23:04

          Most electrical energy in australia comes from coal powered power stations, with typical efficiencies of 35%

        • _Bruce_ on 13/01/2014 - 07:49

          That is average, most cars will average half that.

        • jagsman on 14/01/2014 - 00:09

          I'd love to see your research how you arrived at this value. The turbines themselves all have efficiencies upwards of 90%. Even with transmission losses that is a really low number.

        • eug on 14/01/2014 - 15:49

          If a car engine was very efficient, it wouldn't need such an elaborate cooling system. It would also be very quiet!

        • outlander on 15/01/2014 - 00:15

          @jagsman were you talking to me?

    • MATTDAMON on 11/01/2014 - 10:31
      +1

      Id be more worried about glazing the bores having it idle like that for long periods. Motors arent designed for that (well ones found in cars anyways)

      • maybeamacy on 15/01/2014 - 03:46

        The car locks me out of the navigation functions while in motion though so there's no choice but to use it except for when stopped.

        Maybe I'll just watch DVD's on battery then instead of the aircon too :(

        • Dollarsandsense on 17/01/2014 - 00:26

          Maybe consider watching movies on your laptop and let your car have a break? I get that there is novelty value though!

  • bigticket on 11/01/2014 - 13:03
    +1

    This being ozbargain, to save fuel, there are ways to optimise your AC.

    AC uses a compressor which is essentially a pump that requires energy to run, thats where your fuel comes in and your hip pocket.

    If your AC system is low on charge, assuming its in good condition, then it will be inefficient and produce 'warmer' cool air. So when having the AC serviced have it recharged to specs and if not done for some time replacing the drier at the same time may be a good idea. Also servicing is cheaper in winter months if you can wait that long.

    Most people know when there engine is most efficient, i.e. bad waiting at traffic lights, stop/starting in traffic and good at constant highway speeds. Therefore running your AC when your car more fuel efficient will decrease the amount of fuel used by the AC.

    • _Bruce_ on 11/01/2014 - 17:15

      Most people know when there engine is most efficient, i.e. bad waiting at traffic lights, stop/starting in traffic and good at constant highway speeds. Therefore running your AC when your car more fuel efficient will decrease the amount of fuel used by the AC.

      I don't follow your logic. The engine efficiency you are talking about depends on speed because it is measured over KM traveled. AC energy requirement is fixed regardless of speed. The best speed (purely for the AC) is as fast as your car can go, so you get there sooner and turn it off.

      • bigticket on 13/01/2014 - 16:47

        Your assumption 'AC energy requirement is fixed regardless of speed' is wrong - depends on engine rpm(direct drive off the motor) with increased friction, pumping losses and other variables.

        If you're potting along at 1500rpm and come up to a hill and the engine increases to 4000rpm the corresponding compressor rpm increases proportionally. Where do you think this energy comes from?

        • _Bruce_ on 13/01/2014 - 17:06

          All of this is gear dependent - ie: don't over rev. This is very different to being at idle vs 40 vs 80. Also the energy requirement IS fixed. For climate control the higher rev condenser will cool more, and be turned off sooner. If you have a manual button the temp will still drop quicker and you can turn it off.

        • Tuba on 13/01/2014 - 17:31

          Is there a need to factor in HP of the engine. Power curve over the full range of RPM will rise sharply then flatten on a graph such as those from a dyno? Torque etc is relevant here.

          ie: Engines deliver an increase in HP very cheaply at particular RPMs, and the necessary RPMs for a given increase in hp vary based on factors like cam, head work etc, within a specific model and factory spec. Not to mention gearing and where that places the engine within that power curve for a given speed. When you factor various models and makers and factory specs, you get endless possibilities due to various standard factory power outputs and power curves, then add in custom, and the various makers of compressor, and you get endless possibilities without even considering road and environmental impacts.

          Yes its true the compressor requires a set amount of hp to run it (and various compressors require different amounts of HP), but the cost to deliver that hp varies with much more than simple speed. Obviously it will cost something, but the notion that it must add a similar amount to someone elses, at a specific generic speed is wrong.

          There is no way to give an accurate or even ball park figure. There are just way too many variables.

          Look at a graph from a dyno and look at the steep increase in hp or torque. 100 rpm increase could add 10hp. While 100 rpm at 2200 rpm is less than 5% increase in RPM but will not necessarily equate to nearly 5% increase in fuel consumption.

          An engine at 60kmh might be delivering 50hp, while at 110 its delivering 140 hp. While another engine might be designed for city driving and deliver the bulk of its hp much lower in speed.

          Seriously, no point listening too much to people with different cars. Just work out your own, and run with that. At least look to similar spec cars.

  • Benicio on 11/01/2014 - 15:50
    +3

    For me, I lose up to 50km a tank when using the aircon. A tank give me 450km roughly.

    source: Tradesman constantly stopping, off/on, work ute.

  • rawm on 11/01/2014 - 17:16
    +2

    I'm often picked on by my wife and family for NEVER using my air-conditioning. I live in Metro Melb, have a 2002 Peugeot 1.6L Auto, and can safely say the air con adds 20% to the cost of running my car + it slows the car down by 20% if going under 100kph. Call me stingy or OzBrainwashed, but I'd rather be hot and have the money in my pocket!

    • May4th on 11/01/2014 - 19:51
      +1

      any facts to back up what sounds like a very overstated claim?

      • Shwayne on 12/01/2014 - 00:27

        He's fairly right, but the 20% cost estimations are a bit extreme.

    • SBOB on 11/01/2014 - 20:23

      it slows the car down by 20% if going under 100kph

      so if you are going 99km/h and turn the a/c on your are then automatically going 79km/h..and then if you leave it on 63km/h and then 50km/h and then….etc etc

      • Shwayne on 12/01/2014 - 00:25
        +2

        He's talking about the effect on his RPM's (or the ability to accelerate rapidly), rather than his speed.

    • dannyboi on 12/01/2014 - 11:16

      Your air-conditioning usage is equivalent to 20% of the cost of depreciation, maintenance, consumables and insurance?

    • smartazz104 on 13/01/2014 - 22:36

      I know this is OzBargain, but do people really calculate how much money it will cost them to run aircon in their car and would rather drive around on a hot day with no aircon and rely on the windows being down to save a few dollars? Windows down does nothing; anyone who says otherwise is lying. But I guess with a 1.6L the aircon really does make a difference to power :)

      • rawm on 14/01/2014 - 20:18

        Don't underestimate the power of open windows! Yep, 1.6L and air con is a disaster.

  • Shwayne on 12/01/2014 - 00:24
    +1

    The compressor uses quite a bit of energy to maintain, at an idle it pretty much doubles your fuel consumption.

    Whilst you are driving it can add 5 - 15% (varies depending on the power of your car of course).

    The compressor is used whilst your A/C is active.

    Next time you're in the CAR, sit on idle, and watch the RPMs, then toggle the A/C on and off and observe the result. Do the same whilst you're coasting or driving, with constant pressure on the acceleration pedal. (Take care!)

    You'll notice a loss in torque if you maintain constant pressure on the pedal and you engage the A/C.

    • mangoburger on 12/01/2014 - 09:46

      Not so obvious in a diesel vehicle. I run aircon all the time as it stops the windscreen from fogging up

    • MATTDAMON on 12/01/2014 - 13:13

      It's not as much as you are implying, remember most modern AC compressors are of a clutch design, so they only engage as needed.

  • Franky23 on 12/01/2014 - 10:24
    +2

    As a diesel driver I notice the aircon at half blast (coldest setting), takes roughly 50-75km off a regular tank of fuel. I get anywhere from 800-950km per tank depending on the driving I'm doing. That's about the highest I ever have the a/c, unless it gets to around 40deg or more

    I often wonder if setting the temperature a bit higher and upping the fan speed is more efficient than setting it to cold on a low fan speed? I have always assumed the latter is more efficient.

    I remember my old Mazda 626 (which was a great car) used to suffer a fair bit of power loss with the AC cranking. Modern cars don't seem to experience this as much.

    • _Bruce_ on 12/01/2014 - 12:00
      +1

      I often wonder if setting the temperature a bit higher and upping the fan speed is more efficient than setting it to cold on a low fan speed? I have always assumed the latter is more efficient.

      The former is much better. Fan speed doesn't take much power, and air blowing over your skin helps to cool you down a lot without dropping the temperature of the car. The AC needs to do a lot of work to drop the temperature, and every degree lower inside compared to outside means that more power is needed to maintain the temperature.

  • NaughtyBoy on 12/01/2014 - 12:28
    +1

    Mythbusters tested this on one of their episodes and found that to improve fuel efficiency:
    80kmph+ aircon on and windows closed
    0 - 80kmph aircon off and windows open

    google it to find the episode.

    Cheers.

    • cannedhams on 13/01/2014 - 19:55

      That was with windows wound all the way down. I find that at 100 kh I only need to wind down the windows an inch or so to get ventilation.

      In a Toyota Yaris auto I get about 550 ks out of a full tank, maybe 10% less with ac.

  • ddd on 12/01/2014 - 12:43

    My cars trip computer tells me that my air con uses around 0.5L per 100km

  • randompunter on 12/01/2014 - 14:42
    +1

    Although some what irrelevant to this debate, for us whities of Northern European heritage there is an obvious reason to drive with air-con on that for me is significantly more important than maximising fuel economy. Driving with the windows up filters UVB radiation (and UVA if you have appropriate tinting) thus minimising damage to the epidermal layers and the associated risk of skin cancer. Of course you could always "slip slop slap" before driving.

  • philart on 12/01/2014 - 16:56

    I have the windows down when driving around town as my car speed will always be 50-60 as it's mostly 50 limits around here. Once I get on the highway it's windows up as I don't like living in a vortex and the noise of which the chugging is worst. I've noticed that I can get around 5% better fuel consumption in cool winter conditions when I have AC off continuously. I reckon having the aircon on is about as detrimental effect on petrol consumption as is E10. So air con on plus E10 = 10% worse fuel consumption.

    I often wonder what affect the low or high speeds have, I realise that climate control is a whole different thing. I'm under the impression that high and low is basically fan speed. So low fan speed just sends less cold air into the cabin. Though high fan speed would also burn a tiny bit more fuel by itself, but probably not worth thinking about.

  • slipperyslippers on 12/01/2014 - 17:19
    +5

    Its 44 here today in Perth - doesn't make any difference if the window is up or down - its still raging hot !

    • smartazz104 on 13/01/2014 - 22:37

      Bingo, 44 outside, 54 in the car haha.

  • modsec802 on 12/01/2014 - 22:49

    I heard that car air conditioners do not have any lubricant, they apparently use the coolant as lube, so by not using it then chances are it'll cease up and then you'll have to pay to repair it. Not sure if this is true, but we use ours on 24° each zone in summer and it has never let us down.

    • Tuba on 12/01/2014 - 23:02

      AFAIK, there is oil which circulates with the gas. Lube only needs to be in the compressor as nothing else in the air con needs lube. The fan will probably have grease or some such in its motor/bearings, but isnt technically part of the AC.

      Yes, not using them will perish seals throughout the system. The compressor also has seals in it and lack of use will ruin he ability of the compressor to pressurise the gas.

      Run it once a week for a minute or two and you should be fine.

      I live in Qld, so I just run the AC, its far more comfortable to do so.

    • cwongtech on 14/01/2014 - 17:17

      If anyone wants to know how refrigerators (that's what aircon really is), look up Linde Refrigeration cycle.
      The concept is exactly the same for both to cool gases.

  • akasell on 12/01/2014 - 23:03

    my neighbour had her car parked in the hot sun and turned on the aircon and her windscreen cracked. beware of this. best to put windows down a bit i guess?

    • MATTDAMON on 13/01/2014 - 04:49

      This only happens when you have the aircon set to defrost, ive only ever seen it happen once, and it was with an old front window that wasnt laminated, never seen it happen on a laminated one.

  • onlyletters on 13/01/2014 - 08:52

    Yes, it puts extra load on your engine therefore your engine needs more fuel to stay at the correct RPM.

  • [Deactivated] on 13/01/2014 - 10:20
    +4

    My a/c is running whenever my car is running, all year round.

    As a result I have:

    Cool air in warmer weather.
    Dehumidified air in colder weather.
    Filtering of airborne pollutants.

    The benefits far outweigh any extra fuel consumption that may occur (if you're than anal in the first place).

    Plus I don't drive around for leisure. It's to get from A to B (in which comfort trumps all).

  • Koolbargain on 13/01/2014 - 12:15
    +2

    Hi Guys,

    I did my own experiment for this a while ago.

    TEST VEHICLE: Honda Civic Hatch
    Tank size: 40L
    Average kms per 40L: 500-550km
    Kms with aircon ALWAYS ON: 460-480km
    Used only to and from work.

    In conclusion, I saw a loss of about 30km, which in my opinion is well worth it to have the aircon on running continuously. I wouldn't worry too much about it, having said that I only turn it on when its actually needed.

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