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Front Defrost HVAC & Code 43

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by natenkiki2004, Feb 9, 2021.

  1. natenkiki2004

    natenkiki2004 Junior Member

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    2008 Prius
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    Hi all. I got a used 2008 Prius a few weeks back and am really enjoying it. However, I noticed that the front defrost wasn't working well, having to drive with fog on the inside of the windshield. Even with the AC on and set to front defrost, it takes a long time, a good 20 minutes before it clears. I ran the diagnostic function and got code 43 on the display, relating to the servo motor. Looking under the dash, I can see and hear the upper servo moving but something is still wrong, it doesn't seem to move fully the other direction to allow air out the top of the dash by the windshield. I have floor and vent air, just nothing out of the very top.

    Can anyone provide insight on what steps I should take going forward? This is all still new to me. Thanks.
     
    #1 natenkiki2004, Feb 9, 2021
  2. ChapmanF

    ChapmanF Senior Member

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    Your code, a/k/a B1443, indicates that the car's HVAC controller did not see the position-sensor signal change as it was trying to move the air outlet select servo, so that's consistent with your symptoms.

    The position sensors in those Gen 1 and Gen 2 servos are a known trouble spot, and not hard to clean (if that turns out to be the issue). Here is a thread with information on that. I think the outlet select in Gen 2 is the higher of two servos visible on the left side of the heater case, no? It may be rather more difficult to remove than the temperature blend servo below it.
    Working on a Gen 2, yitznewton found a specialty thin offset screwdriver useful, mentioned in post #13 of the thread linked above.

    It is also possible that something has mechanically broken or jammed, but getting to the servo is probably the first step of investigation in any case.
     
    #2 ChapmanF, Feb 10, 2021
    SFO likes this.
  3. natenkiki2004

    natenkiki2004 Junior Member

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    Thanks for the link to that thread. I'm getting a handle on how to get up there and pull those out. I was messing around and unplugged the lower one. Naturally, I have more codes now. I went to read the codes in a cheap OBD2 scanner and there's no body/HVAC codes listed. Is there any way to clear those codes aside from disconnecting the battery? I'm wondering if I clear the code, maybe the servo will try to move again and can limp me through winter since I don't have a garage.
     
    #3 natenkiki2004, Feb 10, 2021
  4. pasadena_commut

    pasadena_commut Senior Member

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    This probably isn't your issue, but just in case, have a quick read through it. Bottom line, earlier AC work on my car resulted in a botched reassembly where they neglected to reattach some plugs to their sockets, with one of them giving the 43 error code. They also forgot to reattach the TPMS.

    No air out of defrost vents at windshield | PriusChat
     
    #4 pasadena_commut, Feb 11, 2021
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