Most efficient A/C mode?

[Genoz World]

HAHAHAHA.....wow. cheers to you all. for me, i dont want to feel like i've just finished a 5 set tennis match, so the air goes ON.

man, you guys are hardcore. isn't life too short not to enjoy our drive??

[wfolta]

I've been assuming that you can crank up the fan and it uses less energy than cranking down the temperature. Anyone have any specifics on this or tradeoffs?

For example, is running at 78 degrees, but fan on it's highest setting, more efficient than running at 72 degrees with the fan on a low setting? I know there are a lot of variables, but does anyone have any data points?

[hyo silver]

No data points, but that seems to work.

[hyo silver]

Originally Posted by patsparks

...I drove across the Nulabour Plain in my Prius, the temperature outside was a lovely 48 degrees celsius. (118.4 f)

How tough is that, driving in the car with the air conditioning blasting?

The hottest I've cycled in was 44 celsius. I sat in the air-conditioned restaurant at the top of the hill for an hour, drinking root beer and chewing on ice cubes, before half-coasting the last few km.

[wfolta]

I might add that when I first saw someone mention keeping the temp at 78 degrees, I thought they were really fanatical. But I've found that it actually does keep it comfortably cool. It would be uncomfortably hot in the house, but with the vents right in front of you -- even without the air blowing straight onto you -- it's a good temperature. Point the air straight onto you when you need more cooling.

[eddiem]

I have the least MPG hit by, setting the fan and temperature to lowest setting, set air flow selection to face, point the two driver vents to blow on the driver and if your by yourself close the two passenger vents. If you start getting cold increase the temperature, I have also tested this by listening for the wine of the A/C compressor and this appears to make it run less.

[Shawn Clark]

Originally Posted by wfolta

I might add that when I first saw someone mention keeping the temp at 78 degrees, I thought they were really fanatical. But I've found that it actually does keep it comfortably cool. It would be uncomfortably hot in the house,

81 in the house is actually comfortable as long as the humidity is under 50%. The main problem is that some points in the home have a lot more heat gain and will hit 83 or 84 during peak sun with the setpoint at 81. That's why I had to turn the set point down from 82...

Running 78 F in the home is pretty low. The only time temps like this feel stuffy to me is when I'm getting a lot of radiative heating from windows, or more importantly when the indoor humidity is rising because the home is near the balance point and the AC has not run in 12+ hours.

Comfort in the car is influenced a lot by radiative heating through the windows. Direct sun with the car temp at 78 can be pretty uncomfortable...while a shaded passenger will have a different impression.

[timberwolf]

Originally Posted by hyo silver

How tough is that, driving in the car with the air conditioning blasting?

The hottest I've cycled in was 44 celsius. I sat in the air-conditioned restaurant at the top of the hill for an hour, drinking root beer and chewing on ice cubes, before half-coasting the last few km.

Yay, root beer, I can't get it here in the UK. Although that's probably a good thing as I gave up soft drinks.

[zonie911]

Originally Posted by Genoz World

SHAWN - OOUCH. it's 91 degrees here in hollywood today. come on..............

Shawn, it was 95 (that felt to be 97) here in Nashville yesterday and it's still June.
And the humidity is so bad, I've been in Hollywood in the summer and I know it gets hot, too, but setting auto AC on 74 has pretty much kept me fairly comfortable with the auto fan setting, also.

[alevinemi]

Originally Posted by wfolta

For example, is running at 78 degrees, but fan on it's highest setting, more efficient than running at 72 degrees with the fan on a low setting? I know there are a lot of variables, but does anyone have any data points?

You can do that? I thought manually setting the fan shut off the thermostat, shoving you into manual temps.

Also, this might not work for me - I usually have 2 kids in the back seat without a fan hitting them directly. Might work when I drive alone though.

-->Adam