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Defrost not working -- sort of?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by cyberpriusII, Nov 29, 2011.

  1. cyberpriusII

    cyberpriusII Prodigyplace says I'm Super Kris

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    Checked past posts, not finding anything much about defroster not working..

    I'm in the Northwest rain forest. No problems until this year. Car has about 31K on it.

    The last week or so, car fogs up horribly. Defrost doesn't do much and it takes forever to do what it DOES do. No wet dogs, no wet hair. Just standard human passengers in the typical damp Northwest climate.

    Something like this DID happen about two years ago on a trip to Tacoma in January, but I just figured it was the Tacoma air pollution.

    Anything I should check or try?
     
    #1 cyberpriusII, Nov 29, 2011
  2. seilerts

    seilerts Battery Curmudgeon

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    How is the airflow coming out of the vents? Do you have front defrost selected, as opposes to defront+feet?

    Possible problems: damper malfunction inside the evaporator core, malfunctioning PTC heater (fuse, relay, signaling), malfunctioning temperature and/or humidity sensors, clogged drain line in evaporator core (check passenger floor for moisture), lack of engine coolant in system (check the expansion tank level). Take to dealer if you still have 3/36 warranty.
     
    #2 seilerts, Nov 29, 2011
  3. tv4fish

    tv4fish Member

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    Have you checked your cabin air filter? My 2005 was having problems with good air circulation in the passenger compartment - the cabin air filter had a nice layer of leaves/crap which was obstructing air flow. Just a thought.
     
    #3 tv4fish, Nov 29, 2011
  4. cyberpriusII

    cyberpriusII Prodigyplace says I'm Super Kris

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    Well, not the drain line...I had checked that already (amazing, I'd like to say I came up with that myself, but I had checked online before posting here and that seemed like a possible).

    Coolant is not a problem, I checked it over the weekend just because I had a wild idea that wet leaves clogging the inlet screens (whatever those plastic grids that allow air to flow into the car are called) might be the problem -- no leaves, but as long as I was under the hood, oil/fluids got a glance.

    Dampers, PTCs are all greek to me, although I am trying to figure it out by googling the terms.

    Hadn't thought of Cabin Filter. I did check it a few weeks ago and it was spotless, but one never knows what those rascally rodents have been up to recently.

    I'll report back any findings. Meanwhile, any other help is appreciated. Towels and wide open windows in 30-degree weather are getting a bit old
     
    #4 cyberpriusII, Nov 29, 2011
  5. wick1ert

    wick1ert Senior Member

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    Are you able to get coold air and warm air out of the vents? Could it be the refrigerant for the compressor? If that's low/out, you'll just get blasted with moist air, which doesn't help too much. You don't by chance have the A/C off (is this an option in the Gen2?) on accident, and not bringing in the conditioned air?

    I had a Geo Metro without A/C, so the defroster didn't work too well. Wonder if your compressor isn't engaging or is out of refrigerant for some reason (seems unlikely with an 09, but is possible).
     
    #5 wick1ert, Nov 29, 2011
  6. seilerts

    seilerts Battery Curmudgeon

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    You can also run the HVAC DTC check. With your left hand -- thumb and pinkie, hold down the Auto and recirculate buttons on the steering wheel. Then, foot on the brake, turn the Power On (Ready). Things will start flashing, then you will hear a beep as the MFD switches to the climate control screen. If you have a DTC, it will flash in the top right corner of the screen. 21 is the most common, for the solar sensor, and is normal, especially in sun-less OR. Other codes could indicate the source of problem.
     
    #6 seilerts, Nov 29, 2011
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  7. 2009Prius

    2009Prius A Wimpy DIYer

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    Would the same info show up in the diagnostic mode of the MFD?
     
    #7 2009Prius, Nov 30, 2011
  8. seilerts

    seilerts Battery Curmudgeon

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    I don't know. The HVAC diagnostic mode is easier to get to though, as long as you can coordinate holding down three buttons at the same time.

    Can PriiDash read B codes? e.g. B1421 for the solar sensor?
     
    #8 seilerts, Nov 30, 2011
  9. 2009Prius

    2009Prius A Wimpy DIYer

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    Sorry I haven't got the need (or the time) to add DTC reading functionality. If the code is on the CAN bus then it's most likely doable. If it's on the KWP2000 bus then I don't know.
     
    #9 2009Prius, Nov 30, 2011
  10. seilerts

    seilerts Battery Curmudgeon

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    No problem, I was just curious.
     
    #10 seilerts, Nov 30, 2011
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