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Not sure if this would help, or if anyone else agrees, but here goes.

1) I use flow throught to cool the car quickly, the switch to recirc to recool already cool air instead of the 90 degree air outside.

2) I set the AC to 78 degrees. That is fine with recirculated DRY air. The A/C lowers the humidity a lot, especially in recirc. With drier air, you will be comfortable at higher A/C settings.

3)Be careful not to have it set to auto, or it will warm your car to 78 when it is a comfortable 70 outside.

4)Use flow through when it is cooler outside and the humidity isn't too high.

EZ

2007 Silver Pine Mica Pkg 6
 

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That's fine if it works for you. I just leave mine in auto at 73 and adjust it up or down a degree or 2 if I feel too cold or hot. Now that's easy.
 

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The thread started with someone seeking better MPG in a hot area. The lower the A/C setting the more load on the system lowering MPG. I will only heat it to 65 when the time comes as well. It gets down to freezing occaisionally, even here in Sandy Eggo. :)

Try various A/C and/or heat setting in the nifty Prius2G program to see the results. A really excellent program (which I registered immediately!).

EZ
 

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davotto said:
I have been noticing that the energy monitor bars on the dash screen are starting to fluctuate rather quickly; i can go from 1 green bar down to 2 pink bars in a matter of 10 minutes driving (usually in town, but a couple times on long distance trips). Do any of you have the same situation? Or i will park the car with 5 or 6 blue bars showing, and when i start up the car an hour later or so, it has gone down to 2 pink bars. At one point on a trip up the mountains (a one time occurance as i live in the flat desert), i got down to only one pink bar. But the car always replenishes back to blue and sometimes to green. Have any of you experienced this?
Here is the first post. It didn't have anything to do with saving energy. Though what you are suggesting probably works if that is what you are trying to do. I get 50-52 MPG while keeping myself comfy all the way.
 

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I stand corrected, I guess it was further into the thread that MPG and AC came up. I will try and refrain from posting anything useful in the future. :)

EZ
 

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Your post was fine. I was just expressing the opinion that the car does very well for people who just use it like a normal car as well. I think it would be a pretty sucky car if you had to put that much thought into how to select a temperature inside the cabing to get good gas mileage.
 

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The difference between 73 and 78 temp settings is pretty minor. Using the auto setting perhaps not so much. These figures are from the Prius2G emulator. http://Privatenrg.com

AC Deg AC&M HP Total HP AC&M % MPG
70 1.78 25.64 6.94% 47.61
71 1.72 25.58 6.72% 47.72
72 1.67 25.52 6.54% 47.83
73 1.61 25.46 6.32% 47.94
74 1.55 25.40 6.10% 48.06
75 1.49 25.34 5.88% 48.17
76 1.44 25.28 5.70% 48.28
77 1.38 25.22 5.47% 48.39
78 1.32 25.16 5.25% 48.51
79 1.26 25.10 5.02% 48.62
80 1.21 25.04 4.83% 48.74
Off 0.63 24.45 2.58% 49.92

Conditions:
90 Ambient temp
70 MPH
5 MPH headwind <-This had more effect than the temp setting, approx. -2.5 MPG.

Sorry about the formatting. Apparently this board treats tabs or multiple
spaces as a single space. I tried both.

I often drive from Santee (20 miles inland) to Sandy Eggo on the coast. It may be in the high 90s in Santee, and 70 in Sandy Eggo. With the car set to auto and 73 or 78, the car will go into heating mode when I get to Sandy eggo. I am comfortable between 65 and 78 in the car, and if the car had a temperature range rather than a single setting I would go for the auto setting.

At home, my central A/C-Furnace is set to 65 and 80. It automagically switches to heat below 65 and cooling above 80. When it's warm, I wear shorts, when it's cold I put on a sweater.

Al Gore Jr was still getting about 32.14 MPG at 103! More than 2ce what a Hummer gets at any speed! :)

EZ
 

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Hey EZ, you look pretty good with numbers, could you add cost ($) to your calculations?

I might have done some estimating in the past and came up with something like it cost $1 extra per day to ride in a cool car of 75 degrees or a warm car of 80 degrees in the summer. I decided I would rather spend the extra $1 than have to arrive at work all sweaty.

Personal hygene can make a big difference when it comes around to promotion time. :wink:
 

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Our company specifies a long sleeved shirt and a tie for work. I wear a short sleeved polo shirt instead and no tie. I am quite comfortable and non-sweaty with my car set to 78 and recirc. Remember that the AC dries the air. Dry air cools better than moist air, as the sweat evaporates more redily.

Promotion? Only two positions above me in the company, and I don't want to be district manager or president! :)

My next promotion will be in two years when I am old enough for Medicare and full SS! :) 8/16/1943-8/16/2009. Hopefully I will live that long.

EZ
 

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EZ Pickins said:
At home, my central A/C-Furnace is set to 65 and 80. It automagically switches to heat below 65 and cooling above 80. When it's warm, I wear shorts, when it's cold I put on a sweater.
This explains our difference of opinion. At home, my range is between 72 and 75. This seems to be close to my office at work as well. I really like living in that comfort range whenever I'm in a climate controlled environment.
 

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RealAle said:
Hey EZ, you look pretty good with numbers, could you add cost ($) to your calculations?
Using the values of 47.94 MPG at 73 degrees and 48.51 MPG at 78 degrees, if you have a 50 mile round trip commute/day, you will use 1.043 gallons at 73 degrees and 1.031 gallons at 78 degrees. This is a difference of .012 gallons/day. At $3.00/gallon, this equates to about 3.6 cents/day. I think I'll continue with what I am doing.
 

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As this thread has sort of shifted to A/C (the probable cause of the battery fluctuation), here goes my findings so far.

I purchased a "National Geographic" indoor/outdoor thermometer (digital). The Prius tells me the outside temp (just in front of the rad) but not the inside. So I stuck this unit on the silver part of the dash on the passenger side just below the vent (velcro tape again). The temps I see are higher than the "auto" setting. With "auto" set at 24 C I see 28 C in the car, and the system thinks the temp is just fine (fan has slowed down and system is in "maintain" apparently).

Still haven't decided what to do with the outside sensor on this unit. Put it outside or in the back of the car? You can see it in the image below.
 

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A/C maintains humidity by running the compressor. The less the compressor runs, the less it controls humidity. Even in recirc, air does flow into/out of the cabin, and moisture can enter/leave even easier.

So, if you set your A/C temp too high, you'll also raise the humidity.
Fortunately, the Prius has a humidity sensor and will adjust the controls to maintain humidity as well as temp. It either lowers the actual temp setpoint (probably the reason the Prius doesn't show indoor temp), or lowers the fan while increasing the compressor. The air directly out of the vent will feel cooler, but since the airflow is slower, the colder outlet air dissipates into the cabin quicker, reducing its effectiveness in overall cooling.
Also the solar radiation sensor also affects A/C and Fan settings beyond what simple temperature control would require, since radiant heat makes you feel hotter without affecting ambient air temp as much.
 
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