Does running the AC affect your gas mileage?

 

Anything that requires power to operate will effect fuel mileage.
How much is always the question.
A 2 liter engine will take a larger hit than a big loafing along 460.
My 460 consumes so much fuel that I see no difference ac on or off but it has to be something because the power it takes to operate the compressor and fan as well as the added heat load to the cooling system has to consume power.

 

Yes. Any engine-driven accessory requires power and therefore fuel to run. A/C, mechanical fans, alternators, etc all cause a drop in MPG. How much will vary.

 

Thanks for yalls tips, its cause summertime is approaching and its gonna get HOT!!!

 

Yes it does. But you also have to take into account how much wind drag putting the windows down instead takes it toll

 

If you put the windows down make sure you open the back sliding window or you will use more fuel than leaving them up and turning on the A/C if you are going at highway speed.

 

There was an episode of mythbusters where they drove two explorers around a track at a constant speed. One with windows, one AC. No difference between them. But that is just a small part of the story. Acceleration is a killer. I used to drive a car with a 6L v12. Full blast AC with two compressors made no difference on accel. or mpg. But like oleman said, mpg was so bad that it didn't matter.

Friend of mine drives a 4cyl camry. He used to have a sticky note on his AC button that said TURBO

My current DD is a 6cyl. When it's very hot the ac makes a little lag on the engine. But, it has a speed cutoff that disengages the compressor clutch when accelerating. I've got the same car 2yrs older for parts, no speed sensor. With the air running the difference in their MPG gets about 8% bigger. Not too bad, but running 93 octane over $4/gal and getting 12MPG is adds up hah.

Find out if your truck has a compressor shutoff. If it's tuned up well you shouldn't see much difference between air/windows/nothing on the highway. If you're in traffic or accelerating on a ramp try hitting the switch.

 

I almost always agree with Subford, but I wouldn't run on the highway with the windows and slider open. From my experience it causes the headliner to start to sag. From what I can tell, there is virtually no difference between running AC or windows down on the highway. In town is a different story entirely though.

 

There was a deal on the PC the other day Fuel Myths. According to them running the A/C uses no more fuel. This was a gov. run tests. Your foot uses the most fuel lol. Todays newer engines i can belive this easily. On older vehicles you certainly hear a big diff. in motor when turning on A/C.
Running with gate down actually uses more, windows up or down didn't make much diff.
Tounua cover didn't make diff. Take this for what it is worth lol. There were more things that affected mpg can't remeber all of them. oldtimers disease lol.

 

I agree with what everybody else has said. It does take power, but on something like the 460, the exterenal variables (ie weather, traffic, etc) makes it impossible for me to see any difference in fuel economy from tank to tank with and without A/C. My '03 Focus with the 2.0 however sees a 4 mpg hit in highway mileage with A/C and you can feel the car slow down every time the compressor kicks in.

 

Well, I watched fuel consumption like a hawk on farm equipment and construction equipment. In winter months Vs summer months fuel consumption went unnoticed with AC on or off on the same machine. Those were diesels running at lower rpm than gasoline engines but They burned the same fuel in a 10 hour shift AC on, AC off, Ac disabled. I probably turn mine when I get hot, turn it off when its cold, and buy gas when I need to.

 

Yup, big motors don't see the drain a compressor puts on them. My lil 1.9 4banger in my Escort would slow down when it kicked on. It would lose 4-5 mpg in the summer when I ran the air.

My PSD or 460 never noticed a thing. The only thing that killed mileage in those was MPH. Keeping it down at or below 65 really helped. Much faster, the wind resistance really took its toll.

 

Got the A/C fixed in my 89 F250 two months ago, I have noticed only a .5 MPG drop since using A/C. That was averaged over the months before and after AC fixed. I was courious like the rest of us. A .5MPG drop for COOL air works for me. Also I can hear my radio now!

 

I just simply get the cab cool, and then turn the A/C to Vent....And when it starts warming back up...I hit the A/C a lil more..

Save fuel....Less drag....

 

That won't work here in Florida, turn the AC off and the air hits you like a brick with the humidity. I finaly fixed the hard vac line to the AC recirc servo, now I can colder as the air is recirulated and the humidy is removed from the cab. Just got home and stepped out of the truck almost went back in, muggy today and its only the beginning......