Air recirculation in the winter--automatically disabled under 32 degrees

Discussion in 'Gen 3 Prius Technical Discussion' started by PriusOnTheFence, Feb 18, 2021.

  1. PriusOnTheFence

    Joined:
    Sep 26, 2009
    75
    29
    0
    Location:
    MA
    Vehicle:
    2010 Prius
    Model:
    II
    The purpose of using air recirculation in the summer is totally clear, as well as the fact that you want to wait, obviously, till the car has cooled and not to use it for too long.

    All sites that I have read warn against using it in the winter, however, but the only reason they give is that it fogs up the windows. Though this may happen, it does not always.

    So I was wondering if there is something else going on.

    This is especially so since when I start the car and the outside temp is 32 degrees or below, the setting automatically goes to "Outside Air", even if it was set to outside air previously, and I think it reverts to air recirculation when the temp goes up.

    Is this too for the fogging up issue? Because I would have thought that fuel efficiency is helped in the winter too if you recirculate.
     
  2. PriusCamper

    PriusCamper Senior Member

    Joined:
    Mar 3, 2012
    5,164
    2,080
    0
    Location:
    Pacific Northwest, USA
    Vehicle:
    2007 Prius
    Model:
    Two
    I've not read of anything other than the fogging issue... And perhaps the most antiquated thing about this system is how ignorant it is of the toxic nature of air pollution in general. These Prius have no way to protect the occupants if you're for example escaping a forest fire or are stuck in traffic with a bunch of giant diesal trucks. Even when you put the car on recirculate it's still drawing a portion of the toxic air in from the outside. What's most ridiculous about this is as per Tesla, it takes very little effort to use a HEPA air filter to clean out such a small enclosed space while sealing up the external events. Meanwhile, in winter I have to remember to turn off the default back to outside air every time I turn the car off or I'll start to feel sick from the first car exhaust I get behind. It's so ignorant and toxic to assume we're too stupid to prevent our windows from fogging, yet not smart enough to realize that our vehicle won't help protect us whenever we're in a location with toxic air outside the vehicle, regardless of which setting we choose.
     
    PriusOnTheFence likes this.
  3. PriusOnTheFence

    Joined:
    Sep 26, 2009
    75
    29
    0
    Location:
    MA
    Vehicle:
    2010 Prius
    Model:
    II
    HEPA filters for cars do exist.
     
    #3 PriusOnTheFence, Feb 18, 2021
    Last edited: Feb 18, 2021
  4. PriusCamper

    PriusCamper Senior Member

    Joined:
    Mar 3, 2012
    5,164
    2,080
    0
    Location:
    Pacific Northwest, USA
    Vehicle:
    2007 Prius
    Model:
    Two
    Because spending a few extra dollars on every car to protect the lungs of its occupants who presumably are too dumb to know their lungs are at risk would eventually add up to losing millions of dollars in profits over time.
     
  5. Grit

    Grit Senior Member

    Joined:
    Aug 22, 2017
    4,367
    3,313
    1
    Location:
    Wilkes Land
    Vehicle:
    2012 Prius
    Model:
    Four
    Thread topic went off the rails quick. Had it been me, a reply like “off topic” would have thrown my direction.
     
    PriusOnTheFence likes this.
  6. PriusOnTheFence

    Joined:
    Sep 26, 2009
    75
    29
    0
    Location:
    MA
    Vehicle:
    2010 Prius
    Model:
    II
    Ha ha. Agreed. Let's hope someone can really answer the question.
     
  7. sam spade 2

    sam spade 2 Senior Member

    Joined:
    Mar 31, 2018
    4,520
    1,888
    0
    Location:
    USA
    Vehicle:
    2017 Prius c
    Model:
    Four
    It has already been answered.

    The moisture buildup inside can be quite quick and the result quite dramatic........if ICE forms on the inside of the windows.
    This is especially true if there is more than one person in the car.

    The AC will actually turn on automatically in some cold conditions too.
    Best not to second guess any of that.
    In about 99% of the situations, it automatically does the right thing.

    Once it starts producing a decent amount of heat, you can over-ride it to your hearts content.
     
  8. Mdv55

    Mdv55 Member

    Joined:
    Dec 25, 2018
    55
    59
    0
    Location:
    Boston
    Vehicle:
    2011 Prius
    Model:
    Three

    A lot of owners ARE that stupid and some of the others would probably stroke out if they were expected to replace an expensive filter every now and then...

    I drove vehicles for years without a cabin filter and now I have to replace a HEPA filter? Unacceptable Toyota, unacceptable.....DeSiGn FlaW!

    Edit:
     
    #8 Mdv55, Feb 19, 2021
    Last edited: Feb 19, 2021
  9. PriusOnTheFence

    Joined:
    Sep 26, 2009
    75
    29
    0
    Location:
    MA
    Vehicle:
    2010 Prius
    Model:
    II
    Νο, Ι've rarely had dramatic build up inside and never ice...Even when it fogged up, a little air on high or open windows quickly clears it up. The question is, air recirculation is more energy efficient and that should be even more so in the winter--why no mention of that, even with the caveats about condensation, which, as I said, can very quickly be remedied?
     
  10. Grit

    Grit Senior Member

    Joined:
    Aug 22, 2017
    4,367
    3,313
    1
    Location:
    Wilkes Land
    Vehicle:
    2012 Prius
    Model:
    Four
    Sources please that Toyota said hepa is required.
     
  11. Mdv55

    Mdv55 Member

    Joined:
    Dec 25, 2018
    55
    59
    0
    Location:
    Boston
    Vehicle:
    2011 Prius
    Model:
    Three

    It's not, that response was sarcastic. I was replying to the fact that someone seems incensed that Toyota doesn't take the air quality in their cars serious enough for them.

    People lose their minds at having to change cabin filters as is. If people want to live in vehicle bubbles they can easily purchase better filters for the cabin....
     
  12. Grit

    Grit Senior Member

    Joined:
    Aug 22, 2017
    4,367
    3,313
    1
    Location:
    Wilkes Land
    Vehicle:
    2012 Prius
    Model:
    Four
    (y)
     
  13. sam spade 2

    sam spade 2 Senior Member

    Joined:
    Mar 31, 2018
    4,520
    1,888
    0
    Location:
    USA
    Vehicle:
    2017 Prius c
    Model:
    Four
    Because......a perceived possible tiny increase in heating efficiency.....perceived and possible......bears very near to NO weight against a possible safety issue.
    Just because YOU seem to know how to remedy the situation doesn't mean that everybody does.
    And your "remedy" likely more than wipes out that tiny efficiency gain that you are so worried about.
     
  14. PriusCamper

    PriusCamper Senior Member

    Joined:
    Mar 3, 2012
    5,164
    2,080
    0
    Location:
    Pacific Northwest, USA
    Vehicle:
    2007 Prius
    Model:
    Two
    Lol... Reddit taught me that anyone who asks for sources to substantiate hypothetical explanations are not the kind of people you want to interact with unless you like getting trolled.
     
  15. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

    Joined:
    Oct 17, 2010
    41,969
    30,096
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    I’d chime in, that (overpriced) cabin air filters are something that just became “mandatory” in recent years; we drive most of spring, summer and fall (non-rainy days anyway) with the cabin air system OFF, just relying on partially or fully rolled down windows. On cool days roll up the windows and use the cabin air system, but mostly without AC. And virtually NEVER on recirc.

    it is good to use AC periodically, to keep oil in the system circulated; I’m cognizant of that. We tend to use AC more through winter, to dispel humidity.

    I also know constant AC use can leave a lot of humidity in the system, lead to mildew problems, so when using it try to turn it off at least a mile before destination, purposely run the fan fast, and maybe bump temp up too, to clear humidity in the system.
     
    #15 Mendel Leisk, Feb 19, 2021
    Last edited: Feb 19, 2021
    mikey_t and Tideland Prius like this.
  16. Grit

    Grit Senior Member

    Joined:
    Aug 22, 2017
    4,367
    3,313
    1
    Location:
    Wilkes Land
    Vehicle:
    2012 Prius
    Model:
    Four
    your turn- sources that say so.
     
    #16 Grit, Feb 19, 2021
    Last edited: Feb 19, 2021
    Mendel Leisk likes this.
  17. ASRDogman

    ASRDogman Senior Member

    Joined:
    May 29, 2018
    2,912
    1,818
    0
    Location:
    Indian River County, Florida
    Vehicle:
    2010 Prius
    Model:
    Two
    The AC removes humidity. That's why it turns on with defrost....

     
    Tideland Prius likes this.
  18. Tideland Prius

    Tideland Prius Moderator of the North
    Staff Member

    Joined:
    Oct 2, 2004
    41,864
    13,422
    41
    Location:
    Canada
    Vehicle:
    2018 Prius Prime
    Model:
    Technology
    Well practically all modern cars have cabin air filters so him saying “recent years” is a bit of an understatement.
     
  19. PriusCamper

    PriusCamper Senior Member

    Joined:
    Mar 3, 2012
    5,164
    2,080
    0
    Location:
    Pacific Northwest, USA
    Vehicle:
    2007 Prius
    Model:
    Two
    Yes it removes humidity but where that moisture builds up before it drains out can be slightly smelly in some cars which makes people freak out for some reason.
     
  20. PriusCamper

    PriusCamper Senior Member

    Joined:
    Mar 3, 2012
    5,164
    2,080
    0
    Location:
    Pacific Northwest, USA
    Vehicle:
    2007 Prius
    Model:
    Two
    Well, for starters, here's a link for a charcoal infused cabin air filter for $8.53: C35479 TOYOTA CHARCOAL CABIN AIR FILTER FOR TOYOTA PRIUS 2001 - 2009 | eBay

    What was it you were saying about overpriced?

    Also how is your sense of smell? Are you a cigarette smoker? Because lack of a sense of smell or having a smoking habit tends to make people unaware of air pollution and thus unable to know when they need to roll up their windows and put vent system on re-circulate to protect both their long-term and short-term physical health.

    How about during the wildfires last Summer when we had more smoke on the west coast of North America than ever before our time? Did you still drive around with your windows rolled down?
     
Loading...