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Fuel Economy and AC

Discussion in 'Gen 2 Prius Fuel Economy' started by V. Smith, May 3, 2004.

  1. V. Smith

    V. Smith New Member

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    My 2002 Prius is getting terrible mileage 39 city and maybe 45 freeway. Seems to me that my gas engine is always running when stopped when the electric should be on. Most of my driving is city, no traffic, level streets, about 6 miles one way.

    I have Toyota Customer Service involved in this but they are not finding an answer.

    Also, when I press my AC Max button there is no difference in sound or in airflow from the regular AC. Anyone else have that. I am thinking that my mileage is directly related to thinking that my car is constantly in Max air. I also have adjusted my temp gauge to 71 degrees and have seen no difference.

    My car goes into Toyoto tomorrow for them to keep for a couple of days. Any help you might give is appreciated.

    First time in a chat room. Do I look for answers somewhere or what.

    Virginia
     
  2. aarons12

    aarons12 New Member

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    on most cars, Max A/C does 2 things. it speeds up the fan, and it closes the vent that normally mixes in some outside air.

    maybe on the prius it only stops the air mixture, doesn't speed up the fan? i'm just guessing, becuase i DON'T HAVE A DARN PRIUS YET!!! :|
     
  3. mikepaul

    mikepaul Senior Member

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    I settled on 72 degrees for my 'normal' AC setting, and adjust it down if I'm warm. SEEMS like less engine (ICE) use than before...
     
  4. HTMLSpinnr

    HTMLSpinnr Super Moderator
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    In my classic, I left mine set at 75 degrees, it helped the ICE to run a bit less. MAX will force the A/C and ICE on all the time. Normal allows it to cycle a bit.

    That was one gripe w/ the '02. The A/C required the use of the engine. If you can convince yourself to not use it when you don't need it, your gas mileage will go up accordingly.

    The '04 is a godsend in that regard in that the ICE doesn't need to cycle during idle when the A/C is on.
     
  5. Brian

    Brian Member

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    In SoCal it is very hot now, so I have the AC on the second setting and close off the passenger side air vents so I get full power on me. So that way I don't need to cool the car, just me. :D I think that the fuel economy will not be too much effected because of the heat, to keep it warm.
     
  6. jasond

    jasond New Member

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    If your car is warm and you push AutoAC, it should kick the fan in high even if you set it low before. You can then override that if you want, by choosing a lower fan setting manually. Also, if you turn on AutoAC and then increase your temp setting, the fan should slow down as well (not 71... Keep increasing it to 80 or more to prove that this works).

    If you're running with high AC all the time, that would certainly account for the poor mileage, but it might just be because you're running with a high fan and a low temp all the time. Instead of using the auto mode, just turn on the AC yourself, put the fan on the lowest setting, make sure the air is recycling (instead of coming from the outside) and choose a reasonable temp (70-72, say). Shouldn't impact your mileage that much at that point.. My car stays cool in moderate heat with over 50mpg city...
     
  7. randalla

    randalla Member

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    Aside from all of the A/C discussion, since getting your Prius have you modified your driving habits in an effort to strive for higher gas mileage? Things like coasting to a stoplight, minimizing jackrabbit starts and monitoring the power output on the MFD to try to use the engine as little as possible in your driving would help in your quest to improve gas mileage.
     
  8. mikepaul

    mikepaul Senior Member

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    I've been wondering.

    Has anyone had a co-pilot take note of computer reported MPG during acceleration, and seen where easing up to speed at 17MPG (normal for me, espciallly up the hills around here) is ACTUALLY better than jackrabbiting at 7MPG for a shorter time? It would be interesting to see if a shorter acceleration period is actually 'wasting' gas...
     
  9. jasond

    jasond New Member

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    I believe the general consensus is that accelerating rapidly (but safely) to near cruising speed is the BEST way to do it. However, don't accelerate so hard you need to hit the brakes a few seconds later. Engines are more efficient when you give them more to do.
     
  10. V. Smith

    V. Smith New Member

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    Thanks for your answers to my low 39mpg and ac question. What might help is testing the auto by moving my temp higher to make sure it works.

    Could anyone out there actually do a test for me by running your ac with your fan on low, temp whatever, and then hit your max button. Tell me if there is any difference in output of air or sound of the ac. In my car there is absolutely no difference.

    But with my air in ac mode (not auto), temp at 70ish, and fan on low, my gas engine will continue to run at all stops. If I turn my ac button off, the electric engine comes on immediately. Can anyone perform this test on their prius.

    Today at 4 pdt my car goes to the foreman of the shop at a Toyota dealer. The last two times I've had it in diagnostics show nothing is wrong with the car.

    I have consistently gotten 39-41 mpg city for the last year and a half. Driving home from Las Vegas with the ac on the whole way, we got 49 mpg. Make any sense to anyone.

    Thanks.
     
  11. mashmom

    mashmom New Member

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    I can't help you understand your "low" gas mileage, but I am also sitting at around 40 mpg consistently. Granted I only have 1,500 miles on the car. I live in a hilly area and most of my trips are short (5 miles). I'm also using the AC most of the time (set at 72). I'm hoping that maybe I'll get better mileage as the car breaks in better.

    I love, love, love my prius (white #9), but am a little dissappointed in the mpg. Good grief, how could 40 mpg be dissappointing...spoiled brat!
     
  12. mikepaul

    mikepaul Senior Member

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    But would a 'jackrabbit start' be the right way to describe that?

    0 to 35 in how many seconds would be 'rapidly' but not wasteful?...
     
  13. siai

    siai Junior Member

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    Short trips kill the fuel economy---don't expect high numbers with 5 to 8 mile commutes. On the classic never use the A/C max setting. As has been stated before, it forces the ICE to run. Open the windows, cool off the car and then back to A/C auto. Also be sure to check your tire pressures and run them near max inflation pressure--like 44/42 on the classic. Always ran mine there and got great economy and not adverse tire wear.