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Prime's Incredibly Efficient A/C

Discussion in 'Prime Main Forum (2017-2022)' started by stevepea, Oct 26, 2017.

  1. stevepea

    stevepea Senior Member

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    SoCal has been in the grip of a heatwave, with temps well over 100F the last couple days.

    I normally don't use my A/C (I usually just roll down the windows) but when temps are over 100F, there's a limit.

    So yesterday and today was the first day where I had the A/C on the entire time driving around in the Prime -- yesterday on a 25-mile all-EV city trip, and today for almost 200 miles of mixed city and freeway driving (EV & HV) around SoCal.

    I can't believe how efficient the Prime's A/C is. I'm not sure if it's the same in normal Priuses (as this is my first one) but having come from both "normal" cars (ie, Honda Accord, Toyota Corolla), as well as mild hybrids (Honda Civic Hybrid) where the A/C would take a good bite out of the fuel efficiency, I can't believe how little impact the Prime's A/C has. It's barely noticeable.

    I noticed the drain a bit more in EV mode than HV (probably because the AC draws from the traction battery) but it still was quite efficient. And in HV mode -- with the aircon on the entire time -- the MPG seemed to somehow still be pretty much in line with the MPG I normally get with it off in similar driving.

    I tried to be as "efficient" as I could: put the temp at 79F (when it's 106F outside, 79F is actually cool) and turned the fan up to moderately high. I also selected "driver priority" and "econ" mode.

    Honestly, in any other car I've owned (including the Honda Civic Hybrid, which, like the Prime, has real-time MPG meters), turning the A/C on would immediately cut into the MPG a noticeable amount. The Prime hardly at all (especially in HV mode).

    Toyota did a great job with the A/C in this car.
     
    #1 stevepea, Oct 26, 2017
    Last edited: Oct 26, 2017
  2. heiwa

    heiwa Active Member

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    I totally agree with you, driving in the central valley of CA last summer. I too kept AC set at 79-80F in triple digit heat, noticing how quickly and adequately the air felt cool to me. My son who usually demand maximum AC in 2013 Leaf (with heat pump) did not complain my temp setting in PP. The superior efficiency of PP heat pump was also felt in only 1-2 MPG drain compared to 3-4 MPG drain in Leaf's in triple digit heat. PP's heat pump is among many things my wife and I love about our PP!

    Posted via the PriusChat mobile app.
     
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  3. Yeah and even to defog the windshield when there's a lot of rain, the air conditioning had minimal effect on my electric range, AND seemed more efficient than the air conditioning that was in my Prius c. At least in the Prius c, when I used air conditioning, those battery bars would deplete quickly, and the engine used extra energy to recharge the battery, which was also NiMH and needed its own cooling fan.
     
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  4. drash

    drash Senior Member

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    I found an excellent page of Heat Pump info from the Toyota site. Contains basic explanations of how it works.
    HeatPump from priphv1702_en.jpg
     
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  5. Data Daedalus

    Data Daedalus Senior Member

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    The Airconditioning Systems in Prii have always been more efficient than what can be found in standard vehicles. Depending on how hot the weather is, my Prius II suffers no more than a 2 mpg hit - and often less than that.

    Indeed, the highest mpg I ever got out of a tankful (45 litres) of fuel was achieved during a particularly hot summer of commuting in London, with AC in use at least every afternoon on the way home. I got 66mpg @ 634 miles.

    I still marvel at the idea of sitting in congested traffic in 35c heat, with the Prius ICE shutdown and the AC running nonchalantly off the HV battery, while all around you, everyone else is sweltering in the heat with their windows down - especially those with “stop start” technology. Engine shuts down, AC shutdown. Others shut off their ACs to save fuel in heavy traffic.

    I’m not surprised the Prius Prime /PHEV is even more efficient.


    iPad ? Pro
     
  6. Digloo2

    Digloo2 Active Member

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    Here in Phoenix, we've been hitting triple-digits on and of lately, and I've noticed something interesting about my Prime vs. my 2012 Prius V, which is that when I'm running the AC in the Prime, it tends to drop the fan speed when the batteries are under load, like when accelerating from a light or going up a hill. Even manually increasing the fan speed, the computers are limiting them, probably because the system isn't able to cool as much, so the fan speed is cut down to ensure the air coming out is actually a constant temperature rather than warmer at a constant speed.

    The trick will be to see how it fares when it's 110+ outside.
     
  7. Frustrateduser

    Frustrateduser New Member

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    We live in Wickenburg and the temps have been comfortable. But on a trip to Surprise, AZ we found that there is absolutely "NO" air for the person in the back seat. It was miserable. The temp outside was 109 but it was even hotter in the back seat. It took over 40 minutes to cool the car enough so that "myself" in the back seat could breathe. We tried every setting for the air and nothing helped. Not at all happy with our Prius Prime 2018. Why would any company that builds a car that expensive "NOT" have vents for the back seat.
     
  8. Tideland Prius

    Tideland Prius Moderator of the North
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    You're absolutely sure S-Flow was turned off and ECO Heat/Cool was in "normal" mode and not "Eco" mode? (And you were in AUTO A/C not manual A/C...)

    I'm sure other AZ owners can chime in with their experiences.
     
  9. PCPrime

    PCPrime Member

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    The a/c outlet for the back seats are under the driver and front passenger seats
     
  10. john1701a

    john1701a Prius Guru

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    Doesn't sound like you tried this...

    20180614_104555.jpeg 20180614_104621.jpeg

    You have the option of shutting off the flow to the back seat.

    It is that "Priority" feature. Turned on, you'll only get air in front... to just the driver if there is no one in the passenger seat (it detects weight)... otherwise to both in front only.
     
    #10 john1701a, Jun 14, 2018
    Last edited by a moderator: Jun 14, 2018
  11. Tideland Prius

    Tideland Prius Moderator of the North
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    Those are heater ducts.
     
  12. jaqueh

    jaqueh Active Member

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    I’ve enabled this setting before and my backseat passenger said they couldn’t feel any difference. I’ve never seen anything conclusive about vents on the bottom of the seat.
     
  13. MNdriver

    MNdriver Senior Member

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    I’ve had the same experience. I’ve switched the rear seat air flow on and off and my rear passengers couldn’t detect any flow. I’ve never sat in the backseat myself, so haven’t experienced it personally.
     
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  14. PCPrime

    PCPrime Member

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    Owner's Manual Page 492 (Page 502 for Premium & Advanced models), they are called "Air Outlets" of the AC system (both Hot and Cold)
    Note the four arrows under the seats showing the 2 air outlets.

    upload_2018-6-15_9-53-37.png
     
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  15. Tideland Prius

    Tideland Prius Moderator of the North
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    Well any pipe that allows air to flow out of it is an outlet lol.

    Unless you're in manual mode, it'll won't blow cold air out of those outlets.

    For those of us that use the heater in AUTO mode, the climate control will blow warm air out of the FOOT air vents. (That's why the rear floor air outlets are typically called rear seat heater ducts). Cold air typically flows out of the upper air vents. So air vents that are mounted higher up in the car like in the rear of the front centre console or the B-pillar are called rear A/C vents. These are the vents they want.
     
  16. PCPrime

    PCPrime Member

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    Are we talking about Prius Prime? Can you point out to me where are the "higher up rear A/C vents"?

    I'm sure you know that "Air Conditioning System" has both Heat and Cold air supply coming out from those same "Air Vents" depends on the outside/inside air temperature especially A/C on AUTO mode.
    I can hardly believe that there are " FOOT air vents" only blow warm air. You are in Canada so you have heat most of the time but for us in Florida, are those "Foot air vents for heat only" become useless?
     
  17. Tideland Prius

    Tideland Prius Moderator of the North
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    Yes we're talking about the Prius Prime. They do not have the "rear A/C vents" which is why we're having this discussion. Someone mentioned that there are ducts under the front seats. I concur. But I'm just stating an opinion that those ducts are typically used for heat (because you want warm toes and hot air rises) if you use AUTO.

    Now as I said in my previous post, there's absolutely no reason you couldn't blast the A/C and manually change the climate control setting to the FOOT vents and blow cold air out those vents. But they won't do you any good in the summer as the upper part of the cabin will still be stinkin' hot. This is why you use the upper vents and why, typically, the "rear A/C vents" are vents that are located higher up in the cabin. (the most common place in a sedan/coupe/hatch is at the rear of the front centre console).

    If you were using the automatic climate control in its AUTO setting, then yeah, those vents are pretty much useless in Florida.
     
  18. john1701a

    john1701a Prius Guru

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    Back on topic, here's a video of that A/C efficiency...



    I experienced similar results from a totally different drive yesterday. It wasn't as hot, but speed of travel was faster. Since that's a new route, I'm hoping to film it to share in the next few weeks.
     
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  19. Mark57

    Mark57 2021 Tesla Model 3 LR AWD

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    It was 112° actual air temp here in OKC yesterday. Can you say hot? That was a near all time state record. I was out most of the late afternoon in EV full ECO everything including the A/C and I was quite comfortable including ending the drive with a ECO score of 98. Can't do that if you crank down the A/C. So I can testify that the Prime's A/C is amazing.

    20180720_171511a.jpg

    PS, no this was not just road heat. When I left the house, it was 109.9° and rising fast.

    20180720_171955.jpg
     
  20. Roy2001

    Roy2001 Active Member

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    I set AC to 72F and the impact to EV range is very noticeable. The mile per kWh is reduced at least 0.5, but in Sacramento it is around 100F so I am not surprised.