How does AC affect gas mileage?

how many miles to the gallon do you lose from using air conditioning on a 90 integra 5spd?

i moved my air filter to my intake manifold and that almost made my miles to the gallon 1/3rd as much (ran way rich cuz the air was so hot, couldnt get enough air) so i moved it back... it was so much more throaty way back there though, i miss that noise :(

With running it full blast I usually get about 5 less MPG.

from what i hear (maybe not correct) you actually get better milage on the freeway (freeway speed --not necessarily no the freeway for us SoCalers) with the a/c instead of the windows rolled down.

i usually have it on 2 clicks out of 4 if i use AC

how much horsepower does 2 clicks of just fan, no AC.. what about 3 or 4 clicks?


i have my windows down a lot and it bogs a LOT more with the AC on and windows up compared to windows down

doesn't matter how much the fan is on with the a/c. The a/c works as either on or off like that (compressor clutch is engaged or not). On some cars, if you take the temp. switch all the way down, the a/c will stay on no matter what. I keep my temp a little bit above that just in case. Other cars just mix hot hair with a/c depending on temp. position.

does just regular fan affect mileage? i heard it takes away a few HP while using it

it shouldnt be anything noticable. It is electric. I know that electric radiator fans use only a couple horsepower and the blower has to use less than a 1/4 of the power of the radiator fan since it si much smaller.

I lose about 2 mpg with the a/c on my 91 civic lx with a sohc zc engine. Normally I get about 30 but now that its summer and I use that shit on the way back from school (40 miles) I get 28 mpg