Using Car Ac And Saving Fuel ?

eyepea · May 15, 2010

When using the car AC, what action will help save fuel ?

1)

If I set the air intake to "re-cycle" rather than "fresh air", I was told it will save fuel as the AC unit need not be cooling air from outside.

Is this correct ?

Is it good to drive long distances (more than say an hour) with air intake set to "re-cycle" due to carbon dioxide build up or what ever? Is there such a consideration ?

2)

Will setting the temperature setting to a comfortable level rather than max cold, with AC on, save fuel ?

Unlike in AC units fixed in buildings where the temp setting actually sets a temperature, I felt that in my car (nissan k11), the temp setting knob seems to be opening and closing some ducts. So will it save fuel or simply let in less cold air or more cold air into the cabin?

3)

If the fan speed is set to a low comfortable setting rather than max speed, with AC on, will it save fuel ?

Of course with fan speed max, cabin feels colder.

in summery

In a normal car (for e.g. Nissan K11), will the setting of the air intake, or temp knob, or fan speed, affect the fuel consumption with AC on or is it a simple case of irrespective of what ever setting of the above controls, if the AC is on, it will consume the same amount of extra fuel and only way to save that extra fuel is to have the AC off ?

jehan80 · May 15, 2010

eyepea said:
When using the car AC, what action will help save fuel ?
1)

If I set the air intake to "re-cycle" rather than "fresh air", I was told it will save fuel as the AC unit need not be cooling air from outside.

Is this correct ?

Is it good to drive long distances (more than say an hour) with air intake set to "re-cycle" due to carbon dioxide build up or what ever? Is there such a consideration ?

2)

Will setting the temperature setting to a comfortable level rather than max cold, with AC on, save fuel ?

Unlike in AC units fixed in buildings where the temp setting actually sets a temperature, I felt that in my car (nissan k11), the temp setting knob seems to be opening and closing some ducts. So will it save fuel or simply let in less cold air or more cold air into the cabin?

3)

If the fan speed is set to a low comfortable setting rather than max speed, with AC on, will it save fuel ?

Of course with fan speed max, cabin feels colder.

in summery

In a normal car (for e.g. Nissan K11), will the setting of the air intake, or temp knob, or fan speed, affect the fuel consumption with AC on or is it a simple case of irrespective of what ever setting of the above controls, if the AC is on, it will consume the same amount of extra fuel and only way to save that extra fuel is to have the AC off ?

Dude, just how much fuel do you think you can save??? Hope I don't sound rude, but if your that concerned about fuel, maybe you should consider public transport.

NPP · May 15, 2010

afaik,

the cooling level never changes.

and once i saw someone saying even the amount selected on the knob doesn't affect the fuel consumption. (correct me if I'm wrong)

if you want to save some precious little drops, switch it off, lower your shutters

charitha19 · May 15, 2010

eyepea said:
When using the car AC, what action will help save fuel ?
1)

If I set the air intake to "re-cycle" rather than "fresh air", I was told it will save fuel as the AC unit need not be cooling air from outside.

Is this correct ?

Is it good to drive long distances (more than say an hour) with air intake set to "re-cycle" due to carbon dioxide build up or what ever? Is there such a consideration ?

2)

Will setting the temperature setting to a comfortable level rather than max cold, with AC on, save fuel ?

Unlike in AC units fixed in buildings where the temp setting actually sets a temperature, I felt that in my car (nissan k11), the temp setting knob seems to be opening and closing some ducts. So will it save fuel or simply let in less cold air or more cold air into the cabin?

3)

If the fan speed is set to a low comfortable setting rather than max speed, with AC on, will it save fuel ?

Of course with fan speed max, cabin feels colder.

in summery

In a normal car (for e.g. Nissan K11), will the setting of the air intake, or temp knob, or fan speed, affect the fuel consumption with AC on or is it a simple case of irrespective of what ever setting of the above controls, if the AC is on, it will consume the same amount of extra fuel and only way to save that extra fuel is to have the AC off ?

ok my two cents....anywya u are not going to save a lot by turning off the AC.. for me comfort far out weigh the saving on fuel..

however here is a tip.. do not set ur AC to fress air all the time.. as in colombo u can hardly call that fresh air.. and also the temp outside would be hotter than inside ur cabin..

the only time this comes in handy is when ur car has been sitting in the hot sun all day.., and u want the car to cool quickly and reach the desired temp quickly.. genearlly when ur car has been sitting in the sun all day the cabin temp is way higher than the outside temp.. so in this instance put to fresh air... this will save u bucks as the cabin will cool quicker...

SeanD · May 17, 2010

NPP said:
if you want to save some precious little drops, switch it off, lower your shutters

That isn't necessarily true, it depends on the construction of your car and how "aerodynamic" (if that's the word) the cabin is. For example, I've noticed I got more than 80km more on a tank in a Nissan Sunny N16 (1.3l) with the A/C off (not to mention better performance out of that underpowered car), but the same did not hold true for a much heavier Eurocar, where the drag encountered due to the low slung back window and probably many other things, gave me much poorer fuel economy (at a time the AC had gone out on it).

anjulau78 · May 18, 2010

eyepea said:
2)
Will setting the temperature setting to a comfortable level rather than max cold, with AC on, save fuel ?

Unlike in AC units fixed in buildings where the temp setting actually sets a temperature, I felt that in my car (nissan k11), the temp setting knob seems to be opening and closing some ducts. So will it save fuel or simply let in less cold air or more cold air into the cabin?

If U feel that the temp setting knob seems to be openning/close some ducts, never use as a temp controler of an A/C system. Cause when U set the temp knob to Hot posision the said duct id pumping air from the engine room. this not an actual A/C temp control, but use for warming the cabin room specialy in very cold climates

Do U have both "A/C" and "Econ" switches? if it is, use Econ mode.

comments are welcome

Edited May 18, 2010 by anjulau78

SeanD · May 18, 2010

anjulau78 said:
Cause when U set the temp knob to Hot posision the said duct id pumping air from the engine room.
comments are welcome

I was under the impression that setting the temp to the hot position activates the heater (which is also part of the engine cooling system), and it is the hot air blowing across the heater that causes the heat inside? Otherwise it wouldn't work if the engine bay is freezing.

NPP · May 19, 2010

SeanD said:
That isn't necessarily true, it depends on the construction of your car and how "aerodynamic" (if that's the word) the cabin is. For example, I've noticed I got more than 80km more on a tank in a Nissan Sunny N16 (1.3l) with the A/C off (not to mention better performance out of that underpowered car), but the same did not hold true for a much heavier Eurocar, where the drag encountered due to the low slung back window and probably many other things, gave me much poorer fuel economy (at a time the AC had gone out on it).

yes i didn't take that into consideration.

once you exceed a certain speed, you need the best aerodynamics.

pardon me, but what I said may be correct for slow city driving

harshansenadhir · May 19, 2010

SeanD said:
I was under the impression that setting the temp to the hot position activates the heater (which is also part of the engine cooling system), and it is the hot air blowing across the heater that causes the heat inside? Otherwise it wouldn't work if the engine bay is freezing.

correct, actually coolant circulates through the heater matrix all the time (if not removed/blocked due to leaky heater matrix). This was there in cars of 40's or 50's for that matter Only a flap will open and makes the air flows through the said heater matrix. Amount of hot air mixed is depends on the position of the temp setting knob or in climate control versions how system controls the said flap.

In most of systems including sophisticated climate control setting up temp low doesn't necessarily mean that compressor will cut off. Having said that, in climate control systems, if you set the temp above certain degrees (depending on the outside temperature again) will make the compressor to cut off frequently.

eyepea · May 19, 2010

Nope there is no Econ setting in this car .

I dunno if there is much diff for the nissan k11 with AC on or off. Did'nt chk it out yet.

Some years back used to move a toyota petrol van on outstation trips frequently. Tried with and without AC entire trip. Got a diff abt 5 litres per trip of well over 300 km. Not sure if this is supposed to be the case or there was something wrong with the AC system .

Thanks very much for all the input.

Any comments on this carbon dioxide or monoxide build up matter when running on air intake set "recycle" w.r.t SL pls ?

Has anyone any experience of feeling drowsy after several hours of driving attributed to this?

harshansenadhir · May 19, 2010

eyepea said:
Nope there is no Econ setting in this car .
I dunno if there is much diff for the nissan k11 with AC on or off. Did'nt chk it out yet.

Some years back used to move a toyota petrol van on outstation trips frequently. Tried with and without AC entire trip. Got a diff abt 5 litres per trip of well over 300 km. Not sure if this is supposed to be the case or there was something wrong with the AC system .

Thanks very much for all the input.

Any comments on this carbon dioxide or monoxide build up matter when running on air intake set "recycle" w.r.t SL pls ?

Has anyone any experience of feeling drowsy after several hours of driving attributed to this?

5 liters means roughly around 500 rupees as per current prices of petrol. Not much comparing the comfort of A/C specially on long trips you'll be fresh untill reaching the destination. You'll hardly feel tired.

about CO₂ build up, it's a myth. Even if you set recirc at closed position little amount of air will be taken from outside, unless otherwise some maka bass fellow has completely closed those ventilation ducts. I know some A/C fellows who welds the original fresh air intakes to maximize the cooling effect!!.

And NO, never felt drowsy though I always run with recirc on simply because I don't want all dust and dirt to block the pollen filter.

Edited May 19, 2010 by harshansenadhir

anjulau78 · May 19, 2010

eyepea said:
Any comments on this carbon dioxide or monoxide build up matter when running on air intake set "recycle" w.r.t SL pls ?
Has anyone any experience of feeling drowsy after several hours of driving attributed to this?

Theoretically it would be have some problems, but I drive 95' corolla wagon/99' Nissan cefiro. I normally set the air intake to “recycle” level. Even in long journeys like Colombo- Matara (journey will take about 3-4 hours). Never had experienced any bad feelings.

Edited May 20, 2010 by anjulau78

L board · May 20, 2010

eyepea said:
When using the car AC, what action will help save fuel ?
1)

If I set the air intake to "re-cycle" rather than "fresh air", I was told it will save fuel as the AC unit need not be cooling air from outside.

Is this correct ?

Is it good to drive long distances (more than say an hour) with air intake set to "re-cycle" due to carbon dioxide build up or what ever? Is there such a consideration ?

2)

Will setting the temperature setting to a comfortable level rather than max cold, with AC on, save fuel ?

Unlike in AC units fixed in buildings where the temp setting actually sets a temperature, I felt that in my car (nissan k11), the temp setting knob seems to be opening and closing some ducts. So will it save fuel or simply let in less cold air or more cold air into the cabin?

3)

If the fan speed is set to a low comfortable setting rather than max speed, with AC on, will it save fuel ?

Of course with fan speed max, cabin feels colder.

in summery

In a normal car (for e.g. Nissan K11), will the setting of the air intake, or temp knob, or fan speed, affect the fuel consumption with AC on or is it a simple case of irrespective of what ever setting of the above controls, if the AC is on, it will consume the same amount of extra fuel and only way to save that extra fuel is to have the AC off ?

May be this is your first car or the first car with AC. I am sure after using your car for sometime, you yourself will think back about this thread and laugh.