[rc846]

We all know that when you run the air conditioner you get less MPG. But what I want to know is if the A/C is on low (fan speed) will you get better MPG then if it was on high? Or is it going to be the same MPG no matter what the fan speed?

 

[jdeaton]

id assume the higher the fan is, the less mpg. Higher fan speed uses more energy from the alternator which works the engine harder. Either way, i dont worry about it. If im hot, i will turn on the A/C.....

 

[2qik2see]

i was watching this show on spike tv's powerblock, horsepower tv i believe. anyway they said that running your ac on the lowest setting will increase your mpg. they also recommend re-circulating your air to cool the cabin quicker. also don't blast your ac as soon as you start your truck. apparently this is hard on the condenser and what little mph you would have saved running the ac on low will be lost due to letting the truck idle for a long period of time. they recommend getting in and rolling down all the windows and drive for a minute or two the turning the air on with it re-circulating and then rolling up your windows. it'll save you some gas and keep you ac unit living a long life. i've always done this and i've never had an ac problem. my dad taught me this back when i was 16!

 

[DevinSixtySeven]

you mean that recirculating chilled air with the a/c on low will provide better mileage than blasting the a/c with recirc off? that's correct.

changing the fan speed changes the volume of air drawn over the cooling element, right? so if you're moving more hot air, the a/c circuit must work harder. the electrical load is pretty much negligable.

however...i would guess that the difference between hi and lo on the fan is a very minimal difference compared to the compressor being on or off...just a guess...

-Sean

 

[thumbster]

you mean that recirculating chilled air with the a/c on low will provide better mileage than blasting the a/c with recirc off? that's correct.

changing the fan speed changes the volume of air drawn over the cooling element, right? so if you're moving more hot air, the a/c circuit must work harder. the electrical load is pretty much negligable.

however...i would guess that the difference between hi and lo on the fan is a very minimal difference compared to the compressor being on or off...just a guess...

-Sean

Most AC compressors will rob you 5-7 hp under warmer weather conditions. Inside blower motor speed will have very little affect on these numbers. That's not much draw compared to max hp/torque your engine puts out, but under light cruise/light load driving conditions it's pretty noticable - expect to see a 5-10% decrease in your mpg.

 

[Diego]

With my truck I notice no difference in gas mileage whether I have the air cond on hi, low or off. Use it however you feel comfortable and don't worry about it.