Is there now a consensus on AC On vs Windows Down to save MPG
- Thread starter Speak2Mountain
- Start date
My dad had a 1965 98 Oldsmobile that would get so cold with the fridgeaire system that it would put frost on the chrome vents and you could scrape it off with your fingernail. That thing would freeze you outa there. I would say on that car yes, windows down would give better mileage. The new cars I would say it about the same. I like have the air on if going faster than 40 mph.
Originally Posted by Donald
The first ACs would run all the time they were switched on I believe. Add hot air to get to desired temp. (I think). New ACs cycle.
Does anyone remember the car AC kits you could buy from JC Whitney to add AC to your car? Of course without a bigger radiator they would overheat.
I've had climate control for the last couple decades. I just leave it on 70-72. The latest one has duel climate control and the A/C is automatically on when it's on auto. Uses a variable displacement compressor so there's no clutch and no cycling.
Haven't used JC Whitney in a while, they're still around. When the catalog was around, some of the cheapest parts you could buy. I think I still have some tools from them for doing brake shoes that I haven't used in a long while.
The first ACs would run all the time they were switched on I believe. Add hot air to get to desired temp. (I think). New ACs cycle.
Does anyone remember the car AC kits you could buy from JC Whitney to add AC to your car? Of course without a bigger radiator they would overheat.
I've had climate control for the last couple decades. I just leave it on 70-72. The latest one has duel climate control and the A/C is automatically on when it's on auto. Uses a variable displacement compressor so there's no clutch and no cycling.
Haven't used JC Whitney in a while, they're still around. When the catalog was around, some of the cheapest parts you could buy. I think I still have some tools from them for doing brake shoes that I haven't used in a long while.
Originally Posted by wag123
Didn't Mythbusters do an episode on this? If I can remember correctly, their results were that A/C ON always uses more fuel.
Correct.
To me personally, windows down isn't really a replacement for AC because only AC removes humidity.
Didn't Mythbusters do an episode on this? If I can remember correctly, their results were that A/C ON always uses more fuel.
Correct.
To me personally, windows down isn't really a replacement for AC because only AC removes humidity.
Originally Posted by Cujet
I
Ford and many others often run the compressor even when you think they don't.
The a/c compressor on my Fords run in every position on the selector knob except vent,floor and off. On the Nissan there's a button where you can manually turn the compressor off/on. During the winter I usually use defrost until the windows are clear then switch the selector to the floor setting.
I
Ford and many others often run the compressor even when you think they don't.
The a/c compressor on my Fords run in every position on the selector knob except vent,floor and off. On the Nissan there's a button where you can manually turn the compressor off/on. During the winter I usually use defrost until the windows are clear then switch the selector to the floor setting.
It's funny how the only contrast is AC on or off. Vehicles built in the last 40+ years have variable speed fans, many with recirculation modes and ability to set temperature, and cycle on/off as needed.
How much heat your AC is removing has a lot to do with the load it becomes. If you are contrasting full blast and the AC was in good condition, windows down probably wasn't an option as it'd be too hot.
Regardless, it's not just dust and pollen that get in with windows down. There's rain (when you forget to roll them up parked) but most of all exhaust from everyone else, and in certain areas of some cities it also makes you a magnet for harassment (or at least more interaction than you wanted) whether it be punks or homeless people or hookers, etc.
How much heat your AC is removing has a lot to do with the load it becomes. If you are contrasting full blast and the AC was in good condition, windows down probably wasn't an option as it'd be too hot.
Regardless, it's not just dust and pollen that get in with windows down. There's rain (when you forget to roll them up parked) but most of all exhaust from everyone else, and in certain areas of some cities it also makes you a magnet for harassment (or at least more interaction than you wanted) whether it be punks or homeless people or hookers, etc.
Originally Posted by DeafBrad
Another way to look at it... on a fuel efficient car, it would be $2-3 maybe over a tank of fuel. In hot or humid areas $2-3 for comfort over a tank of fuel is a bargain.
Exactly.
Another way to look at it... on a fuel efficient car, it would be $2-3 maybe over a tank of fuel. In hot or humid areas $2-3 for comfort over a tank of fuel is a bargain.
Exactly.
Originally Posted by Quattro Pete
Originally Posted by wag123
Didn't Mythbusters do an episode on this? If I can remember correctly, their results were that A/C ON always uses more fuel.
Correct.
To me personally, windows down isn't really a replacement for AC because only AC removes humidity.
Being in the PNW, I totally agree!
Originally Posted by wag123
Didn't Mythbusters do an episode on this? If I can remember correctly, their results were that A/C ON always uses more fuel.
Correct.
To me personally, windows down isn't really a replacement for AC because only AC removes humidity.
Being in the PNW, I totally agree!
Originally Posted by wag123
Didn't Mythbusters do an episode on this? If I can remember correctly, their results were that A/C ON always uses more fuel.
Yes. But their findings were busted later. If I recall correctly, Mythbusters used a constant speed of 50 mph or less for their study. I can't recall if it was Mythbusters themselves or someone else that proved their conclusions in err. Their speeds weren't real world, and didn't produce the sort of wind resistance that is typical of highway driving.
Didn't Mythbusters do an episode on this? If I can remember correctly, their results were that A/C ON always uses more fuel.
Yes. But their findings were busted later. If I recall correctly, Mythbusters used a constant speed of 50 mph or less for their study. I can't recall if it was Mythbusters themselves or someone else that proved their conclusions in err. Their speeds weren't real world, and didn't produce the sort of wind resistance that is typical of highway driving.
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MythBusters did this ages ago, yes, it's better with the windows up and the A/C on.
In my Fiat 500, turning on the AC will drop MPG by 5-7 at 65 mph.
Originally Posted by BHopkins
Originally Posted by wag123
Didn't Mythbusters do an episode on this? If I can remember correctly, their results were that A/C ON always uses more fuel.
Yes. But their findings were busted later. If I recall correctly, Mythbusters used a constant speed of 50 mph or less for their study. I can't recall if it was Mythbusters themselves or someone else that proved their conclusions in err. Their speeds weren't real world, and didn't produce the sort of wind resistance that is typical of highway driving.
Correct. The track and vehicle they chose for the experiment could not handle higher speeds. The tires would squeal in the turns at higher speeds so they limited it to 50 MPH for safety.
Originally Posted by wag123
Didn't Mythbusters do an episode on this? If I can remember correctly, their results were that A/C ON always uses more fuel.
Yes. But their findings were busted later. If I recall correctly, Mythbusters used a constant speed of 50 mph or less for their study. I can't recall if it was Mythbusters themselves or someone else that proved their conclusions in err. Their speeds weren't real world, and didn't produce the sort of wind resistance that is typical of highway driving.
Correct. The track and vehicle they chose for the experiment could not handle higher speeds. The tires would squeal in the turns at higher speeds so they limited it to 50 MPH for safety.
At this time you probably want your windows up anyway. Less chance of catching any germs that might be floating around. The homeless are really crazy to be asking on the road, about 1/4 of them have it around here so they're basically asking you for a donation and potentially giving you something in return too. Although you're more likely to get it indoors than outdoors.
At low speeds, windows up always uses less fuel, assuming you can tolerate the resulting temperature and humidity. In any other circumstance, the answer depends on numerous variables, including but not limited to
Speed
How many windows, how far down
Efficiency of AC system
Shape of car body
Temperature setting of AC
Wind
Speed
How many windows, how far down
Efficiency of AC system
Shape of car body
Temperature setting of AC
Wind
I would guess that the difference between the two choices is minimal. Depends on whether you want fresh air straight from the window or cool air from the blower.
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