Is it possible with the air conditioner turned on to get better gas milage than with the A/C off?

I have always been told or led to believe that A/C kills gas milage. Two weeks ago I drove up north and around all weekend with the A/C on and thought I had more gas left than my same usual running around with the A/C off.

???

Steve

 

Not really.

When the air con is engaged, it's a parasitic load on the engine which takes horsepower to drive the compressor.
There must have been some other variable.

 

AC - windows up
No AC - windows down

Windows up - less drag
Windows down - more drag

I'm not an engineer but, I did stay at a Holiday Inn Express last night.

 

This is what I've believed all along too, but my results were undeniable. My wife was the one who pointed out that we wouldn't have to fill up to complete the return trip AND I drove around all week...albeit not much...on the remaining tank.

What type of load does the compressor put on the system when NOT running? It's always driven by the same sepentine, so it's never truely disconnected.

FWIW, I removed the AC system from my 94 'Stang for the very reason you mentioned.

Steve
'98 F150XLT 4x4
'94 Mustang (http://www.stangparts.com/howto/supe...ker/index.html)

 

Raoul hit it IMHO. Increased drag at high speeds with the windows down likely saps more power than the AC at those same high speeds.

 

Everything I've read points to the same. Modern vehicles generally are very aerodynamic and the compressors are becoming more efficient. The disrupted air flow with the windows open will suck more mileage than the a/c. There is still a small load on the engine even with the a/c off.

 

This was on Myth Busters (the TV show).

On a banked oval track at open ride type speeds.......AC on got better mpg.
The reason was as stated......windows down = lots more drag.

 

It just amazes me when Raoul is correct!

 

I have noted on several occasions that using A/C did in fact seem to offer better fuel milage but have done no fillup tests to see except that there was more gas in the tank at the end of the same runs that are done at about 2 week intervals, 140 mile round trips at upwards of 70 mph.
Hard to believe from previous old standards but it seems to happen.

 

You ain't no more amazed than I am.
I guess that Holiday Inn Express stuff really does work.
I kinda feel bad now that I stole their towels.

 

most efficient is windows up and no ac. no hp loss on engine and now drag from windows down. but who could stand that in 100 degree heat

 

I have kept track of my gas mileage in previous trucks and have noticed no discernable difference with the air on or off.
On the 97-03 trucks I think the compressor even turns on in winter if you are on certain heat settings (I believe floor and vent the compressor will not be on and all others it is on). I used to hear mine cycling on & off in winter and the dealer said thats fine.

 

I'm getting significantly better mileage with the windows down. I get opposite results from my wife's Navigator though. I just got my new 2001 Supercrew but there is a noticable drag on the motor when the air is on. With 107,000 maybe I just need a tune-up?

 

That's just wrong

 

The advantages of a properly working air conditioner system far outwiegh the cons of any "parasitic load". (i.e.: not swetting your *** of in 90 degree plus temps)