Q: Force electric air heater (after exhaust pipe heat exchanger bypass)

Discussion in 'Gen 4 Prius Care, Maintenance and Troubleshooting' started by LinuxGuru, Jan 3, 2025 at 4:00 AM.

  1. LinuxGuru

    LinuxGuru New Member

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    I have well known problem with coolant leak in exhaust pipe heat exchanger used for quick heating. Faulty heat exchanger now bypassed with a pipe, yet now there is a problem with heating - it looks like almost non-existent during drives 15 - 25 min long (so far I had no longer drives after service made few days ago). Windscreen remains icy/foggy even at -1..-2C (30.2 .. 28.4F) for very long time because no hot air stream. Forcing strong air flow to windscreen (with button) helps a bit but its quite annoying anyway.

    Is it possible somehow to force air conditioning system to turn on electric air heater? I tried to raise internal temperature on climate control yet it changed nothing (possibly) because engine coolant stays at low temperature and air heater turns on only if outside temperature well below -1..-2C (30.2 .. 28.4F)?

    A/C is always on, auto fan speed mode.

    Thanks in advance for any suggestion(s).
     
    #1 LinuxGuru, Jan 3, 2025 at 4:00 AM
  2. BiomedO1

    BiomedO1 Senior Member

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    Your thermostat is probably stuck open, allowing hot engine coolant into the radiator before it gets up to temperture or you somehow looped-out your interior heat exchanger on the by-pass.

    Hope this helps.....
     
    #2 BiomedO1, Jan 3, 2025 at 9:35 AM
  3. LinuxGuru

    LinuxGuru New Member

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    Biomed01, thanks for reply, you meant thermostat or valve, or this is valve with built-in (or connected to) thermostat?

    PS. Small update - air stays completely cold after 1 hour of drive (~50 km).
     
    #3 LinuxGuru, Jan 3, 2025 at 12:19 PM
  4. bisco

    bisco cookie crumbler

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    what's the electric air heater, heat pump? shouldn't have anything to do with your bypass, and should come on without being forced.
     
    #4 bisco, Jan 3, 2025 at 1:34 PM
  5. Mendel Leisk

    Mendel Leisk Witness Leader

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    Did you approach dealership? Out of the time/miles limit for the TSB? Or unending "back order" issue with the part?

    There really should be a class-action lawsuit for this horse manure. Ditto for 3rd gen EGR.
     
    #5 Mendel Leisk, Jan 3, 2025 at 1:41 PM
  6. LinuxGuru

    LinuxGuru New Member

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    Yes, I approached domestic dealer, unfortunately, in European Union its NOT warranty.
     
    #6 LinuxGuru, Jan 3, 2025 at 2:46 PM
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