Which AC setting do you think is best?

The condenser works by compressing the refrigerant. When that refrigerant later expands, it causes significant cooling. But it needs the fan also to move that cool air into the passenger compartment.

The fan alone works simply by moving air around.

Thus, the fan must use less energy, even if the fan is at maximum and the condenser at low. Compression takes a lot more work than just moving air around.

The AC will cool the car even if you are not in it. A fan will not lower the temperature in the car at all. It relys on the principle that moving air causes water to evaporate off your skin quicker than still air would. And that water pulls heat away as it evaporates. This is why a fan causes you to cool off some.

Thus, a fan is useless without a human with the ability to evaporate water off the skin. So don't leave your fans on when you go off to work. The electric motor actually adds heat to your house, and moving air does nothing for your couch.

 

Get the Huper Optik nano ceramic film installed for all windows but the front glass at a 35 rating. This will actually help reduce the heat load significantly.

I should have done it, but failed due to a snafu at the closest dealer, 100 miles away.

 

76

 

I concur with flareak. I have it set at 76 and my mileage pretty much doesn't suffer because of it, relatively speaking of course.

 

79 in Missouri in the summer? Gaaaaah, I'm glad I'm not in that backseat.

 

I have the auto set for 76 as well and I haved been getting great mileage in heat.

 

I think one of the keys to being comfortable with a highish AC setting is to have the blower aimed at your upper chest. This is the point that Evan made and I wanted to reinforce it. And if there is no passenger, then to turn off the vents on that side. Thus, with the outside temp at 90, you might be just fine with an AC setting at 80.

And if it's super hot out, aim at least one of the vents at your face.

However, if there are people in the back seat, there is no way to aim it into peoples faces. To make it comfortable for them I think you need to have the setting a bit lower.

But the higher the setting that you can tolerate, the better will be your energy use.

And since I was about 40 before I had my first car with a working AC, I have no problem with kids in the back seat enduring a higher setting. But not my in-laws.

 

In my very low humidity southwestern climate, high speed fan works great with cabin set at 77 - 82 -- depending whether passengers are in the back of the car.

If I could aerate my back, I'd be even happier. Perhaps beads would help ?

 

I use 74 and auto.

 

That doesn't actually work for me, Prius04. Initially, I like the driver side vents pointed at my face but after that, I point them up and away. I also keep all of the vents open, pointed in various directions because I like the entire cabin to be cool. It seems to me that the people in the back would be comfortable too, thataway.

 

<div class='quotetop'>QUOTE(prius04\";p=\"110506)</div>

I find that doesn't really work if it's sort of humid and about 80 degress outside. The A/C doesn't turn on and you end up with 80 degree humid air blown at you which gives me a clammy feeling. At which point, I have turn the A/C on to reduce the humidity, and then cool the cabin, since it would be too cold to have it blast in my face at the temperature setting required for the A/C to kick in.

 

<div class='quotetop'>QUOTE(kaysea\";p=\"110566)</div>

Yes, but I thought this thread was heading towards what to set the AC to and at the same time save the most on MPG.

Cooling the entire cabin will have a bigger hit on the MPG than just concentrating the cooling on the driver alone. Seems to me that if you aim the air at your face or trunk, you can have the AC number set higher. Thus, be reasonably cool and at the same time optimize MPG. Actually, if comfort were the issue alone, I too would cool the entire cabin.

This is where I was coming from.

 

Yes, Prius04, but the way I do it, the MPG doesn't go down and even goes up a bit. Using recirculation part of the time helps. But isn't the a/c auto going to dial down as the entire cabin cools anyway? Just having the a/c blowing on me doesn't seem to be efficient in that regard. It feels good initially though.

 

The higher the temp. setting the less the A/C compressor runs and thus, less energy consumed. My 22 miles commute is mostly 60-70 mph with a few stop lights and usually no congestion (HOV lanes No. VA). Mileage with A/C @ 79F 47-48 MPG; w/o A/C, 2 front windows full open, 50-51 MPG. The variable that is unknown is the increase in drag with the windows down. Of course, the drag increases as the speed increases. The A/C MPG effect can be determined by conducting the following test. Pre-test conditions: warm-up car fully; flat highway; temperature greater than 85F; area where you can use cruise control for 40-50 miles; A/C set temp at least 10 degrees lower than outside temp to load compressor. Test: place car in cruise, set A/C, press reset on MFD, drive 20-25 miles, record MPG; turn off A/C including fans, open 2 front windows, press MFD reset, drive same speed and distance as with A/C on, note MPG. Report results to this forum. Improvements to test are requested. Test should be run at different speeds and outside temps.

 

<div class='quotetop'>QUOTE(kaysea\";p=\"110411)</div>

with the air on, it will reduce the humidity, so that wouldnt be bad especially when the outside temp is 20+º hotter.

as for me, i dont do hot very well so my mileage suffers when it gets hot. lately its been in the mid 80's, my air is set to 72º and my mileage is at 54.5 down from 60.5... oh well

 

Wow, you're good, Dave. I can get 60 if I don't run the a/c at all. That's not going to happen this summer, probably. But that's what it reads on days when it's cool out. It's still good enough, though, to be able tell coworkers that "yep, I'm only getting 52 right now". They hate that so I try not to bring it up too often. One coworker said "damn, I only get 42 and that's on my motorcycle."