Efficiency question

[bakedweasels]

OK, here's something that has been bugging me for a while: if I want a certain temperature in my car and I achieve do that either by turning the air conditioning down really low and the fan very low, or by leaving the A/C significantly higher and turning the fan up, which is better for the car/my fuel economy?

Comments

[twe]

You're not the only one. Though I'll probably still blast my A/C when it's very hot.

[algorithmancy]

My idle conjecture is that the fan is better bang for your energy buck than the A/C, especially if you point it at your skin.

My reasoning is that some of the fan's benefit comes from "wind chill factor;" it doesn't have to cool the whole car, it just has to get your sweat to evaporate.

I suspect it actually depends on how many people you are keeping cool. The more people in the car, the more efficient I would expect AC to be.

As to which is better for the car, I'm not sure your car cares. :)

[izmirian]

That was also my line of reasoning. I would rely more on the fan, though clearly at some point increasing the fan speed doesn't increase the cooling much. But if your starting point is a very low fan speed then I suspect that increasing it is efficient.

[bakedweasels]

Thanks all. Yeah, I had been running with low temp/low fan for a while thinking how clever I was, but I think in reality that with just me in the car the fan is going to get me most of the way there and is less energy-intensive than cooling off air another 10 degrees. So I thought I'd ask.

[countertorque]

I agree. In watts, I think it's a push. But, because the fan is only making you think it's cooler, it's allowing the cabin to run hotter and easing the work load on the A/C.

BTW, I read an article in Consumer Reports awhile back where they tested effect of having the A/C on and the windows down. They discovered that the car did not care if the A/C was on and that having the windows down at like 50 mph was a very small effect. I was surprised.