Air Conditioning

I would say it hardly affects fuel economy as the a/c compressor is powered by the traction battery instead of by a belt connected to your engine like a normal car.

 

I think you will be pleasantly surprised how little effect the a/c has on fuel economy. Now that nice weather as come here to NC, my mpg has skyrocketed (10+ mpg) and I run the a/c daily in the 76-78 degree range. The heater seems to be the real mpg enemy on our beloved Prius'.

Happy Cooling!

 

A/C consumes energy. There is no free lunch. That said, as others have pointed out, the A/C on the Prius is very efficient. Likewise you have losses from open window driving, and you do need to keep the HV battery cool, so you are limited in your options.

If you are worried about mileage, go ahead and use the A/C, but use it in moderation.

Tom

 

I seem to be down 2mpg on this tank, but I am not in eco mode and don't have my windows tinted yet. I don't have enough miles to really know the effect. I wouldn't worry about it. Showing up hot, sweaty, and uncomfortable versus maybe 20 miles less per tank isn't a good trade off. If anyone has good numbers from last summer I would like to know them.

 

Re: Air Conditioning - How to use?

Q1. Will setting the temperature to, say 70 on a 85 deg day automatically use the AC if the climate control is set to Auto but the AC button is off? Or is the use of the AC button required for the AC function?

Q2. If the climate control is set to Auto, then will having the AC button on force the use of the AC all the time? or will the Auto function use the AC only as needed to maintain the set temperature?

Q3. Like in winter, there was a temperature (68 deg) that minimized the use of heater functions, is there a similar temperature that will result in the AC getting used in a less aggressive manner?

 

Re: Air Conditioning - How to use?

A1: The AC button controls the AC compressor. If it is off, no cooling is done, even when climate control is set to auto.

A2: No. AC is only used as needed for cooling and dehumidification. The AC compressor is variable speed, so it runs only as much as needed.

A3: There is no magic number. The cooler the setting, the harder it works.

Tom

 

I have been averaging a real 48.43 mpg in mixed driving (city stop and go 5 miles/hwy commute 15 miles) with just me (sorry HOV practitioners). Today I took my first longer hwy trip with the family (5 total), full load of luggage and AC on for 235 hwy miles. My real (not car readout) mpg was 49.56mpg. I drove at different speeds, but mostly hwy 70-80.

As noted on this thread, the AC doesn't run off belts (no drag on engine), so, realizing that fact and that I am driving with a full load of humans and luggage, I would say you can use the AC without penalty to MPG. I believe it has been proven that over a certain speed, it is more fuel efficient to keep the AC on than lower thw windows in any car, let alone with the Prius aero-conscious body design.

 

the AC has surprisingly little effect on the mileage. Was also true on my '07.

 

One way to save fuel when using A/C is to set it so that it is always about 5C (about 10F) less than outside temperature. I read that this should feel already cool enough, considering that the A/C removes humidity.
In any case A/C is not for free as mentioned from others, though I expect the Prius A/C to be the mot efficient on the market. I don't know how many cars out there have an all-electric A/C system.

 

I have the AC on all year around even in winter to reduce humidity. It has no effect on the MPG as I see it compared to heating. Heating kills MPG in the extreme sense. I feel poor in the winter because I don't even turn on the heating till atleast after 10 minutes driving when the engine heats up a bit.

 

To repeat another responder, there is no free lunch. AC always uses some power. Whether through belts or electricity or some other path, some drag must get back to the engine.

That said, the 2010 Prius serves up this lunch at a lower gas cost than any previous automobile. But do remember the inherent problems of expressing fuel use in MPG instead of L/100km, magnifiying the apparent difference. A 1 mpg reduction to a 20 mpg SUV is actually a greater fuel cost than a 6 mpg reduction to a 55 mpg Prius.

This is also the first car to use a newer type of valve (ejector?) that is more efficient than traditional expansion valves.

 

I've only had my Prius since April, and it is just starting to get really hot in Vegas this week. My last car was a 2004 Acura TSX and the A/C in the Prius sucks in comparison. I have 35/5 3M High Performance tint, AirBlue80 on the windshield, and the solar roof package, and the A/C still gets nohwere near as cool as my old car. MPG is suffering as well because I am running in Power Mode to get the additional boost out of the A/C. Anyone else in Vegas or AZ have any comments or suggestions?

 

Set the temperature to 68 degree or below, you will be surprised how cold it blows.

 

Thanks, I will give that a try on tomorrow's commute. I've only been running it in the 70-76 range.

 

Please explain the logic that "running in Power Mode will get additional boost out of the A/C."

 

Yes that person only needs to get out of eco mode to get the ac to work at full power. Switching to power mode does nothing to help with ac.