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Heater not blowing warm air after long way downhill?

Discussion in 'Prius c Care, Maintenance and Troubleshooting' started by DKTVAV, Jan 12, 2015.

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  1. DKTVAV

    DKTVAV Active Member

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    On my way back down from Big Bear mountain the heater stopped blowing warm air, just like outside air, before reaching the 10 freeway. I turned it to Max but still no warm air, what's wrong? It's working today on the way to work though but it's only less than 4 miles trip.
     
    #1 DKTVAV, Jan 12, 2015
  2. bisco

    bisco cookie crumbler

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    all i can think of is the engine turning to dissipate excess regeneration, (no combustion) and cold air blowing through the radiator. maybe if you put it in neutral, (illegal?) and use the friction brakes, the engine can run normally to produce heat.
     
    #2 bisco, Jan 12, 2015
  3. GregP507

    GregP507 Senior Member

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    Right, when the engine is being used to dissipate energy, it's not burning fuel, therefore it's not producing heat for the heater. This is where electric elements in the heater housing would make sense. That would help dissipate excessive regen energy.
     
    #3 GregP507, Jan 12, 2015
  4. DKTVAV

    DKTVAV Active Member

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    It's not a good idea when going downhill from 8000' and also like you said "illegal".


    So is my electric heater not working?
     
    #4 DKTVAV, Jan 12, 2015
  5. GregP507

    GregP507 Senior Member

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    News to me if the Prius has it.
     
    #5 GregP507, Jan 12, 2015
  6. bisco

    bisco cookie crumbler

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    they would make sense, but you don't have any. actually, they wouldn't make financial sense for toyota.
     
    #6 bisco, Jan 12, 2015
  7. GregP507

    GregP507 Senior Member

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    So they said.
     
    #7 GregP507, Jan 12, 2015
  8. bisco

    bisco cookie crumbler

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    i didn't hear them but i'll take your word for it.(y)
     
    #8 bisco, Jan 12, 2015
  9. DKTVAV

    DKTVAV Active Member

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    So how to get warm? Plug in a portable electric heater?
     
    #9 DKTVAV, Jan 12, 2015
  10. bisco

    bisco cookie crumbler

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    if you ride the brakes hard, the engine will run.
     
    #10 bisco, Jan 12, 2015
  11. GregP507

    GregP507 Senior Member

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    Plug in where?
     
    #11 GregP507, Jan 12, 2015
  12. jdcollins5

    jdcollins5 Senior Member

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    The engine coolant temp would have to drop drastically to not have any heat. Assuming the coolant was up to temp, would the engine temp drop that much coming down the mountain?
     
    #12 jdcollins5, Jan 12, 2015
  13. GregP507

    GregP507 Senior Member

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    We either take him at his word, or we say it can't happen.
     
    #13 GregP507, Jan 12, 2015
  14. bisco

    bisco cookie crumbler

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    i guess it would help to know the outside temp, the heater setting before starting down, how long he had been driving before starting down, how far down he got before the air turned cool, how fast he was going, if he's grille blocking...
     
    #14 bisco, Jan 12, 2015
  15. GregP507

    GregP507 Senior Member

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    If you believe that grill-blocking works.
     
    #15 GregP507, Jan 12, 2015
  16. bisco

    bisco cookie crumbler

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    i don't have any scientific data, but i believe it would help slow cooling of the engine if it's really cold out and you're at highway speeds.
     
    #16 bisco, Jan 12, 2015
  17. GregP507

    GregP507 Senior Member

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    I'm sure it helps, it's a common practice here, but I'm skeptical it could account for much of a difference in this case,
     
    #17 GregP507, Jan 12, 2015
  18. fuzzy1

    fuzzy1 Senior Member

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    Absolutely!

    Get a ScanGauge or other engine monitor, dial up the engine coolant temperature, and just watch it plummet. It won't drop to ambient, but it will fall sharply until a threshold is crossed and the engine is forced to burn some fuel.
     
    #18 fuzzy1, Jan 12, 2015
  19. DKTVAV

    DKTVAV Active Member

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    Cigarette lighter?
    I remember I used the brakes a lot to slow down and lot of traffic ahead.
    I started at the top of Big Bear mountain and immediately going down from 8000' so I don't know the engine is warmed up to temp or not.
    And yes, I use grill blocking but only haft of both parts.
    My stupidity: I have a scangauge but didn't remember to check the engine temp. I haven't looked at it for more than a year so I forgot it's there.
     
    #19 DKTVAV, Jan 12, 2015
  20. GregP507

    GregP507 Senior Member

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    I believe the Prius 12V lighter socket tops out at around 300W overall, so you may be asking for the moon there.
     
    #20 GregP507, Jan 12, 2015
    Last edited: Jan 12, 2015
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