I’m a completely non-mechanical/technical person, but if spoken to as though I’m a semi-moron, I can often grasp the concept (analogies always work well). This being said, and presuming anyone out there has an interest in educating this clueless newbie, I’ve always wondered:
Does raising the temp or fan speed of your car air conditioner use up more horsepower or energy or gas or whatever?
Does driving with a window open a few inches and the AC on affect gas use / horsepower (I don’t even know if I’m using the right words!)?
How much horsepower does running the AC take from the engine? (Again, I’m probably wording this badly…)
How much more gasoline is used when I run the AC (if any)?
Many thanks for any help!
Disputin, The Debauched One
1 a archaic : to make disloyal
b : to seduce from chastity
2 a : to lead away from virtue or excellence
b : to corrupt by intemperance or sensuality
Anything that requires energy is going to reduce your fuel efficiency according to the law of conservation of energy (Energy cannot be created ior destroyed except in a nuclear reaction) so unless you have CANDU under you hood, and I don’t think you do…
As for whether it reduces your horsepower, i doubt it because the condesnor and fan are probably powered by a seperate motor which is electric and runs off your battery. The batteryu does derive it’;s power from the ICE, but think it receives a constant current anyway, so…
Plus the ammount of energy required to move a small motor like that is minimal.
Fuel yes, horsepower no.
Peace.
“Mmmmm, Sacrilicious…” – Homer Simpson
If you need a graphic solution, http:\ alk.to\Piglet
The compressor certainly does run off the engine, and will require additional HP and fuel to make it run. The blower/fan, while powered by the battery, will also increase the total current load on the battery/electrical system. To keep the battery from discharging, the alternator will output additional current, again at the expense of fuel/HP. Running headlights, playing obnoxious rap at 127 DB Spl @ 1 meter, or using the cigarette lighter will do the same. There is no such thing as a free lunch …
A point in every direction is like no point at all
Thanks for the informative link (black mark for me, for not finding that on my own)! I hadn’t even thought of the aerodynamics angle.
Disputin, The Debauched One
1 a archaic : to make disloyal
b : to seduce from chastity
2 a : to lead away from virtue or excellence
b : to corrupt by intemperance or sensuality
#1)The blower motor, which is just the electric motor attached to the fan that blows the air for the heat or AC, draws lots of current when on hi speed and will cause the alternator (the thing that keeps the battery charged. It is attached to the engine and driven with a belt) to increase drag on the engine. This is like puttin’ on the brakes just a little bit.
Increase the temp? There may be some different systems out there, but, the amount of hot/cold balance usually has no effect on how much the compressor (the thing that pumps the rifrigerant gas and increases drag on the engine to a greater extent than the alternator)runs. MAX AC usually runs the compressor all the time, normal setting will cycle the compressor.
Modern cars are extremely aerodynamic, so using the AC uses up power from drag on the engine, and putting the windows down also increases drag, except the drag is on the body which the engine is pushing through the air.
3)The amount of HP it takes to run the AC is different for different systems. One would need a dyno to know for sure, but it is easy to feel the loss in power when the AC compressor comes on.
Since most systems turn the AC compressor off when more than about 75 to 85% throttle is applied, the total power that the engine may produce is not affected by the AC system directly. The extra heat created by the AC system is likely to create a loss in power.
The amount of power used is different for different cars. If the AC uses 20 HP, the mpg loss in a Camero Z-28, or a Cadillac (they usually have at least about 250 HP) will not be that great. In a Toyota, the AC will use more gas, but opening the windows will probably use more gas than running the AC.
I think I said that so a non-mechanical type person could understand - HTH
Excellent info, 1420Vel.GN! Thank you. Your explanation was right on. I think I get it now!
Disputin, The Debauched One
1 a archaic : to make disloyal
b : to seduce from chastity
2 a : to lead away from virtue or excellence
b : to corrupt by intemperance or sensuality