mpg with the temp of the air cond

Hello, just a question about the airconditionner, does anybody know when and why the A/C suck fuel? I don't know if it more we cold the temperature or when we put the fan on the hi or low position.
Do you think it will increase the mileage if we don't set the temperature too cold?

 

When you turn on your A/C, it engages the clutch on the A/C compressor. It causes more drag on your engine, in turn making the engine work harder. If you just turn the temp knob to cool, it won't be as cold as your A/C, but it also won't affect your gas mileage.

 

A/C on = lower mpg in city driving.
the temperature or the fan speen will not make a dif.

Mythbusters did a test between two identical trucks. one using a/c and one with the windows down while driving on the highway. the one with a/c drove farther than with windows down. Im not sure how far it was, I think he drove for about 40 more mins.

 

The over under speed is usually about 40 mph (rough estimate).
If you are going BELOW 40-keep the windows open because the drag from the open windows is less then the drag on the engine of the AC compressor.
ABOVE 40-Roll up the windows and turn on the AC.

And +1 about the temp not mattering.

 

Back in the older cars (say Buick and Olds etc) the A/C could draw up to 20 HP off the engine to run the compressor. Now, ours are much more efficient and only draw 5-10HP when the compressor kicks on. You can feel it mostly on a slight incline where HP becomes challenged by the hill itself as well as windage, then you add the third variable of the A/C engaging, there's that instantaneous slight drop in power for like 10 seconds then it comes back and so on. This is not that noticeable on our trucks with the V6s, but the I-4s will feel it a little more...but still not as badly as the small cars with say 130HP or less. That A/C still requires the same draw of power and the less overall power your engine has the more you'll feel it.

 

Also, turning the temp knob warmer does not help mpg if the AC is on... it's just a way for the girlfriend to annoy me by inefficiently warming previously air conditioned air.

 

why would u leave the windows up and sweat it out? just does'nt make sence u have ac use it. how much money do u think u are saving getting all gross and sweaty in a closed up truck when its hot out. i just dont get people like u. but hey maybe u like sweating?

 

Oh really? Are you sure?So I can turn the temp in the maxcold position and the fan on the hi position and it will not affect the mpg? I will maximise next time my a/c if there are'nt difference with fuel comsuption

 

i agree this is a retarted conversation in the first place.

 

*retarted? Don't you mean retarded?

It's not a stupid thread. It's a valid question that deserves a valid answer.

In simplest terms: A/C on = worse gas mileage than if it's off, due to reasons stated in the above posts.

In addition, your mileage will suffer much more greatly from every 5 mph increase in speed after 55 than A/C will ever hurt it at any speed. I've seen big drops in gas mileage with my scanguage tool when reading between speed increases. It's amazing what wind drag will do to performance.

 

To only add more technical information to this thread, the environmental selector may make a difference in the mid 50/50 position as the AC compressor will engage when the Freon needs to be pumped into the condenser for cooling to take affect. It will cycle on and off as needed. So if the incoming air is already cool, the compressor may run for 10 mins, off for 5, on for 10 and so forth. If the incoming air is warm, it will run continuously. So in recirculation mode with full heat, the air will effectively be warm, fed through the condenser (cooled) and heated again to the environmental setting.
But now were talking technical, not rational; as it would account for only hundredths of a penny in fuel difference (even at $3.6/gal).

 

Recycle gives you more cold air, but run regular vent to dry out the coils before you shut off , turn off the AC a little bit from home and leave on the fan..Rich ....City MPG does suffer, but you bought the truck to be Cool....LOL