I've heard conflicting information on the effect of the AC compressor on fuel milage. I'm not interested in getting into the whole windows up/down vs. AC debate, but wondering if removing the belt from the AC compressor from September - May would be noticable in the mpg. Has anyone tried the?

I was replacing the serpentine belt on the power steering & water pump last night and it got me thinking about this an I couldn't find a good thread.

 

As long as the compressor is not engaged,i don't think it would make any difference at all

 

Works only if done on moonless night of 13th...

No really there are hundreds variables of this magnitude: biggest is u foot, then leaking fuel lines, tuneup etcetc. Theres no gauges to measure the fuel consumption of rotation of a belt. Theoretically yes: but then what kind of wax are u applying on the wind resisting surface, how long is u dragging antenna and how often is it up?

 

if the a/c is off you wouldn't see hardly any difference compared to totally taking the belt of. the engine is only spinning a light pulley when the a/c is however when its on it starts compressing the refrigerant.

if anyone is curious on the a/c vs. window thing i personally got better gas mileage with the driver's side window down than having the a/c on... but it doesn't bother me either way personally. if its hot, i'm turning on the a/c.

 

I understand there are a lot of variables in this, that is why I was interested if anyone had tried this and had before and after mpg data. There is some amount of power required to turn the belt and I'm not sure if it is significant. If no one has tried it, I may this fall.

 

Good luck trying to use the defrost with the ac compressor unhooked.

 

I would think the defrost would work, it just will not dehumidify. I know this was a battle on cars I've owned w/o ac before.

 

What exactly is the connection between the defrost and ac compressor? I had a feeling that when I turned on my defrost, the compressor was being engaged but didnt know if it was normal or not.

 

To help get the moisture off the glass, the compressor is engaged to blow dehumidified air (as mentioned). Take the belt off and it will just blow air on the glass. Greatly lengthening the time it takes to clear up the glass.

 

it's normal, you A/C pulls the moisture out of the air.
and the frost on your windshield is water droplets (condensation) that froze so, as you dive it starts to thaw and it has to go somewhere.

 

Antenna increases drag. Drag has to be compensated with more pwr. Pwr comes only from burning gas. (Which consumes more pwr:listening std radio or antenna drag? lol)

Are u going to tst drive antenna down, or up? Mark down also all of the other '500 variables' that are on par with u belt... Your task is utopia: drive today, drive tomorrow and your difference will be bigger from weather or tire pressure than one such minuscle engine component. Mind u, engine has some other components also than what u see or feel...

What are u going to test mpg with? Maxima fuel gauge??? lol...

Btw. I am not against testing, really go ahead. But the test results have no value if when error margin is bigger than result: you end in the gloBall warmuppet -hoax that is being used to rob all of US with taxes. Btw. There is absolute no global temp increase as the error margin is bigger than the suggested 0,5C during last 100 yrs. (bubble busting FACTS please view: http://www.junkscience.com/)

 

I tend to fill my tank untill I can't get it to take any more. I figure my mpg using gallons at the pump and miles driven. I also am well versed in statistics and know it would take something more than 1-2 mpg averaged over a month's driving to say it really helped. I was just curious if anyone had tried it, no sense in repeating a test that someone has all ready proven is a waste of time.

 

Sure u will. And will satisfy uself, but not anybody else.

- That station fillup gauge has error margin bigger than what u test
- Fillup "untill I can't ..." depending on the car angle (multiple variables there) , fillup difference could be 1-1½gallons. No how much that represents as errormargin?
- miles driven depend on your gauge, tires, load, road etc variables may vary 1-10%. How u drive, even more.

So your test error margin is AT LEAST about 10x the to the amount what u want to measure. LOL AND MORE LOL.

Just make the calculation of masses: what are the rotational masses in a engine, do research, don be dumb and stubborn. Then take the speed these masses and calulate energy. Your belt might be somewhere 0,001% of all engine consumption. Still you have not touched moving the 3000lb and variables that affect it.

The only way to get smtg else than laughter, is to buy precision measurement gauges capable (600$?) of measuring milliliters of used gas. Set up your engine on a bench, out of car. Do measurements with and without a feature u want to measure. Repeat those measurement 10x, and calculate average. This is the only way to have knowledge. The test setting you depict is fed with humbug numbers, out comes crap.

Do your test, but build your tester first. Then provide pics and tell how your tester works... then give out a diagram on used energy in different belt temps and engine rpm's.

 

At this point I'm sorry I asked the question. I'll take it from the responses, nobody has tried it any nobody thinks it's worth investigating.

 

Then u did not read the detailed answers which do not condese from air without trouble.

Fact: one belt is not worth investigating: whatever u do, dont do without FIRST making a detailed plan and calculations. And getting adequate measurement equipment...

 

Have you ever took off the ac belt and spin the compressor pulley?

 

FWIW, I still get my 23 MPG with the AC compressor on, in the city.