How does the fan setting and temperature control on my car A/C affect gas usage?

Everyone knows that running your A/C causes the driver to use more gas. During the summertime the temptation is too great to run my A/C. The question I have is this: Once the A/C is on that's it you are wasting gas no matter what the setting? so you just as well crank it up? or will I use less gas if I turn the fan on low rather than high? or will I use less gas if I turn the temperature knob closer to a moderate temperature rather than all the way to the blue?

How does the fan setting and temperature control on my car A/C affect gas usage?
The fan setting makes no difference on fuel economy because that runs off your battery. However when the compressor kicks in that will make a slight diference in fuel economy. The alternative is to roll down your windows, which effects the stramlineness of your car. So that the fuel cosumption is about the same. So crank up the A/C and enjoy.
Reply:The difference in a higher or lower fan speed setting would be so minimal I can't imagine you could possibly notice a difference unless you plotted it out over the entire life span of the vehicle and then I doubt it would amount to anything.And turning the temperature knob up would only defeat the purpose of using the A/C in the first place so use your A/C and enjoy it,that's what it's for.
Reply:to limit the on time of the compressor use lowest fan speed you can stand and keep the temp lever at the coolest setting and let the evaporator freeze up switch control the compressor [blend air systems only]


[models with real temp control] turn temp setting to an acceptable mid range temp that you can live with and don't touch it for the rest of the trip[newer cars respond faster] older systems a change in the desired temp setting causes periods as long as 15 minutes where heat and ac are mixed, wasting fuel.


note personal fuel savings will probably be insignificant... however if everyone did this i believe it could turn into a LARGE blip on someones radar screen.
Reply:Your right, as long as the Ac is on you might as well crank it up, the fan has no effect on gas because it runs on electricity. Only the AC compressor is run by the engine and robs the engine horsepower and gas mileage. So turn the AC on and crank it up cold.
Reply:when u buy a car the AC costs about1200 dollars.. ...so if u drive a honda getting 30 mpg with no ac and 29 mpg with it on in 100 miles you save 1/10 of a gallon.... at 3.00 per gallon..you save 30 cents on a 2 hour drive......not me i'm running the ac on full if i feel ilke it....