Turning on the a/c

[caineroad]

I know turning on the a/c decrease fuel economy, is it true the colder you turn the a/c, more fuel it wastes? or does not matter?

And the fans, if I switch it to 4 max setting or the circulation button, does it use more fuel as well?

Lastly, does the alternator generate more electricity through fuel burning if the battery is losing charge because I use too much cigarette lighter accessories, or turning the speakers loud?

During the summer, it's really hard to resist, I get grumpy when I am sweaty in the car.