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front defrost

Discussion in 'Gen II Prius Care, Maintenance and Troubleshooting' started by bobkat21, Dec 9, 2005.

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  1. bobkat21

    bobkat21 New Member

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    I am having trouble turning on my front defroster. I puch the button on the streering wheel and the light lights up but the defrost des not work. I tulk it to the dealer 3 times and now they are going to replace the button in the steering wheel. I was just wondering if anyone else is having this problem?
  2. Bill Merchant

    Bill Merchant absit invidia

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    I've had no trouble at all. Now that it's colder, I'm actually turning it and the rear defogger on when necessary, and it takes very little time to clear. Sorry you had the problem. BTW, you can turn on "Recirc" for the front defrost, as well as the regular AC mode.
  3. afternoonnap

    afternoonnap New Member

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    Try pressing the Auto A/C button, and setting a desired temperature, before pressing the front defrost button. That will let the system control all aspects, whereas otherwise defrost will not override fan speed.

    BTW, you can turn on front defrost on the Climate screen of the MFD as well as from the steering wheel button. It's at the bottom left.
  4. DanMan32

    DanMan32 New Member

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    If the light turned on, nothing is wrong with the steering wheel button.

    Are we talking about front defrost, or rear defrost? The former will have a curved top edge, the latter will be almost rectangle.
  5. paprius4030

    paprius4030 My first Prius

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    Yeah, Dan is on to something LOL. I don't think anything lights up when you turn on the front defroster. Are you sure your hitting the right button?
  6. jeromep

    jeromep New Member

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    1. Put the system into full auto by pressing the auto a/c button on the wheel until the AUTO A/C light on the dash is on.
    2. Set temp to a temp you want to be at, something comfortable, but not too cold.
    3. Press the front defrost button on the wheel. That is the one with the curved shape on it, not the oblong shape. The oblong shape is rear/mirror defrost.
    4. If having the system in full auto and then pressing the correct defrost button doesn't work, then you have a problem, however if the defrost light is iluminating on the dash then the button isn't the problem. Why would the dash light come on if there were a problem with the switch.
    Sure you might have a problem, but I'd start with the suggestions of this group before having the dealer do surgery. I would strongly advise you to run your climate control system in auto all year long and let the car take care of itself. Set it and forget it.
  7. hdrygas

    hdrygas New Member

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    And then no crying when your M.P.G. goes down because the ICE is running all the time.
  8. engunneer

    engunneer Member

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    If the light lights up, then the button isn't broken! Does the indicater also come on on the MFD in the climate screen? it says front with the curved window logo.

    Also, you can set the temp even with the defroster on. The higher the temp, the harder the fan will blow.

    Press Auto/AC on the steering wheel twice when in defrost to turn the climate control off.

    When you say "Doesn't work" what exactly do you mean? No heat? No fan? are you set at "max cold"?
  9. DanMan32

    DanMan32 New Member

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    Exactly, if you see a light in the dash, then obviously the steering wheel button (or MFD) has told the AC Amplifier (ECU) that you desired defrost, and the amplifier told the dash to turn on the light. Now that doesn't mean there isn't something wrong with the amplifier, or its ability to control the defrost, though it is unlikely there's something wrong with the front defroster if everything else works, since the front defrost uses the same fan, heat and AC that plain old heat and AC would use. However, the rear defroster has window resistive heating that is independent of the AC system itself.
  10. Mojo40

    Mojo40 New Member

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    I keep my 05 in the garage. In the morning, I keep the climate control off for the first 5-10 minutes. No problem even at 28 degrees F. The ICE runs a bit at first, then shuts off to give me the pleasure of stealth mode until I leave the neighborhood. Later, after the engine runs a bit (to support higher speeds), I turn on climate control. I'm not sure if this helps MPG much, but I noted the engine runs a lot more if climate control (and especially defrost) is on. Truth be told, I'm just an engineer looking for any excuse to screw with all the fun controls and hack my Prius.
  11. DanMan32

    DanMan32 New Member

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    You observe correctly. The system will be less tolerant of the coolant temp dropping if you demand cabin heat, and therefore will run ICE more frequently to maintain coolant temp for the benefit of your comfort.
    At least for your temperature comfort. Not so comfortable if you are more focused on MPG than cabin temperature.
  12. galaxee

    galaxee mostly benevolent

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    i think afternoonnap was the first to hit it on the head. you have to have the fan on in order for the defroster to do its job.

    i say, the less they do to the car the better. DH has taken it apart enough for me. of course, i do trust the work he does but i prefer it to be left well enough alone.
  13. Mojo40

    Mojo40 New Member

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    Actually DanMan, I have forgotten to turn on Climate Control. About 10-15 minutes into the commute, I start to notice. I'm originally from northern Michigan and used to drive a 73 VW beetle, so perhaps I am used to not getting heat.
  14. adllewellyn

    adllewellyn New Member

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    I can't seem to get my front defrost to work at all (light comes on and all, it's just not effective) - will try the whole set-to-auto thing. I live in Texas (where it is still hot and muggy in October) and wonder if that's part of my problem... thanks.