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Driver side face vents not blowing

Discussion in 'Prime Care, Maintenance and Troubleshooting' started by fkat, Feb 28, 2023.

  1. fkat

    fkat Junior Member

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    2017 Prius Prime
    Model:
    Prime Advanced
    I hope this helps others that may come across the issue I had.

    Last week all of a sudden the driver side vents stopped blowing on our 2017 Prius Prime 68K miles. Upon turning the car on, the AC control grayed out for a minute or so before you can control it. Diagnostic mode (push AUTO and recirculate within 5 sec) displayed the code 43. Techstream also showed B1443 Air Conditioner-Air Outlet Damper Control Servo Motor Circuit. As always, I searched PC for anything similar, and found 1 post with the same issue on Prime with no solution. So, I reviewed the manual and got some ideas from few Gen 3 posts I saw.

    I tried some noninvasive ways first. Disconnected the 12V to attempt to clear and reset the car which didn't fix. With Techstream I cleared the MIL but B1443 came right back. Next, I tried initializing the motors via Utility. It runs for about a minute to complete but the code did not go away. The motor in question is the No 1 radiator damper servo motor on the driver side.

    It was time to dig deeper. The repair manual says to remove the motor and manually check the dampers. It also says to connect the motor to the No 3 motor connector harness, then perform a manual test with Techstream Active Test. There was no way I was going to remove the entire dashboard as the manual says. Gen 2/3 posts and some YouTube indicated you can go through the footwell. It was tight but managed to remove the motor assembly. Here are the steps compiled from few sections of the repair manual to remove trims to get to it.
    1. DISCONNECT CABLE FROM NEGATIVE AUXILIARY BATTERY TERMINAL
    2. REMOVE INSTRUMENT PANEL FINISH PANEL END LH
    3. REMOVE INSTRUMENT CLUSTER FINISH PANEL GARNISH ASSEMBLY (2x connectors)
    4. REMOVE FRONT DOOR SCUFF PLATE LH
    5. REMOVE COWL SIDE TRIM BOARD LH
    6. REMOVE NO. 1 INSTRUMENT PANEL UNDER COVER SUB-ASSEMBLY (2x 8mm bolts, connector)
    7. DISCONNECT HOOD LOCK CONTROL LEVER SUB-ASSEMBLY (unclip and pull out)
    8. REMOVE LOWER INSTRUMENT PANEL FINISH PANEL ASSEMBLY (1x 10mm bolt, 2x connectors)
    9. REMOVE LOWER NO. 1 INSTRUMENT PANEL AIRBAG ASSEMBLY (2x 10mm bolts, 10 Nm)
    10. REMOVE FRONT NO. 1 CONSOLE BOX INSERT LH
    11. DISENGAGE LH LOWER CENTER INSTRUMENT CLUSTER FINISH PANEL SUB-ASSEMBLY
    12. REMOVE NO. 1 AIR DUCT (3 claws, 2x 10mm bolts 9.8 Nm)
    13. REMOVE NO. 1 AIR CONDITIONING RADIATOR DAMPER SERVO SUB-ASSEMBLY (2x screws)
    upload_2023-2-28_18-56-21.png
    Everything was pretty straightforward but these tips may help. Make sure you disconnect the battery before. To remove the hood release you have to pry up the tab located underneath the lever then slide it out. Before removing the bolts for the airbag unit, I removed its trim. It’s held by hooks on top and bottom of the airbag unit so you’ll need to undo them. I didn’t disconnect the airbag but just set it aside. I also couldn't remove the air duct (step 12) but it would've given me more room and visibility.

    With the motor out, the dampers moved fine. I separated the servo motor from the gear assembly (2 screws) then cracked it open. It was clean inside with no sign of damage or loose connection. I tested the battery with a 9V battery just to see if it moves and it did. The motor contacts looked clean so I snapped the housing back together. Tested the motor by itself without the gear assembly on the No 3 connection which is at the bottom of the radiator. The motor tested fine and all normal. If it passes the test then the manual concludes AC harness is bad and to replace it but I was not prepared to do that.

    At this point I connected the No 1 servo motor to its connector and reconnected No 3 motor. Then I attempted to initialize the servo motors again with Techstream. Voila, the code cleared and I was back in business. I put it all back together and the vent mode control is working again.

    removed trims
    upload_2023-2-28_18-57-35.jpeg

    upload_2023-2-28_18-58-22.jpeg

    couldn't remove the air duct
    upload_2023-2-28_19-0-48.jpeg

    good look at No 3 servo motor for the rear vents
    upload_2023-2-28_19-1-4.jpeg

    No 1 servo motor sub-assembly with the connector off
    upload_2023-2-28_19-2-48.jpeg

    looking straight up at the motor
    upload_2023-2-28_19-3-57.jpeg

    removed servo sub-assembly
    upload_2023-2-28_19-4-40.jpeg

    upload_2023-2-28_19-5-58.jpeg

    inside the servo motor
    upload_2023-2-28_19-6-19.jpeg
     
    bisco likes this.
  2. jnpSacto

    jnpSacto Junior Member

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    Prime Advanced
    Hello fkat! This is why I love PriusChat! My 2017 Prius Prime Advanced with 59k miles has developed the EXACT same problem about a month or so ago, includiing the grayed out AC controls for the first minute or two of vehicle operation! I appreciate your detailed explanation of the diagnostic steps you took and the steps you took to ultimately resolve the problem. Having said that, given that I have the exact same circumstances, is there a short-cut solution that you would recommend to me without having to do everything that you did?

    Edit: I tried your diagnostic "AUTO + RECIRC" button push and also got code 43.
     
    #2 jnpSacto, Apr 14, 2023
    Last edited: Apr 14, 2023
  3. bisco

    bisco cookie crumbler

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    Someone asked this just yesterday, I hope they find this post
     
  4. ColoradoBoo

    ColoradoBoo Senior Member

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    So you didn't replace anything...just taking it apart and putting back together fixed it?
     
  5. jnpSacto

    jnpSacto Junior Member

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    I'm a little concerned that I wont get an answer to my question. the OP hasn't been on in over a month.
     
  6. bisco

    bisco cookie crumbler

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    @fkat maybe he'll get a notification
     
  7. fkat

    fkat Junior Member

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    Hi sorry, I’ve been away. The issue came back 2 months later. @ColoradoBoo yes I did not replace anything because the motor worked and all the contacts seemed to be okay so put everything back. B1443 didn’t come back until few weeks ago. It’s probably an intermittent contact failure inside the servo motor gear dial thing. It was pretty greased up inside and I didn’t want to take that apart then.

    This issue is causing the AC control locked up for 2-3 min after power on; not great since it’s getting hotter.

    I could get a new servo (P/N 8710647200 $140 from dealer) or swap #1 and #3 servo since they are the same part to see I get a different code. #3 controls the rear vent. I will post an update, hopefully soon.
     
    ColoradoBoo likes this.
  8. fkat

    fkat Junior Member

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    Prime Advanced
    Update:

    Finally had some time to dig in there again and removed the #1 servo sub-assembly. It was not responding at all. Here you can see the pulse is at 128 which means it's not responding at all.
    upload_2023-5-21_15-52-48.png

    When I apply power to the motor (pin 1-2) it turns so I suspect there is a bad contact inside the servo. I disassembled it.
    upload_2023-5-21_15-58-5.png

    Now I just rotated this servo back and forth by hand using the gear. It moves well enough and didn't feel anything wrong. After several turns I assembled all back together then tested with a batter to make sure it rotates.
    upload_2023-5-21_16-3-50.png

    I reconnected the servo motor by itself to the harness and let it hang while I tested. The motor moved as the car started. Techstream shows the Pulse at 256. Proceeded to Active Test.
    upload_2023-5-21_16-8-24.png

    upload_2023-5-21_16-10-54.png

    The motor responds to pulse between 164-256.
    upload_2023-5-21_16-11-4.png

    The problem is gone at this point. Let's see how long it takes for the symptom to come back. If it does again then I will replace the servo.
     
  9. ChapmanF

    ChapmanF Senior Member

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    As you can see when you take the servo apart, the only position indication built into it comes from switch contacts that make two on/off pulse trains.

    The job of counting those pulses and knowing what the current position is belongs to a little IC right in the wire harness connector that plugs into the servo. In some cases, it's those ICs that go bad (fixed by replacing that small harness, if that's what it is).
     
  10. fkat

    fkat Junior Member

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    Thanks for the info on the harness. I believe my servo has an intermittent connection problem. It’s been 2 days of driving roughly 100 mi with AC in AUTO and so far no error code.
     
  11. jnpSacto

    jnpSacto Junior Member

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    Prime Advanced
    hi fkat. Oddly, about two weeks ago, just as a brutal heat wave hit Central California, everything started working again! No longer did I have to wait a few minutes for the climate control to turn on. No longer are the driver's side body vents not working. Everything is working as it should! I don't quite understand how these two seemingly unrelated problems are connected, but they seem to be! I will keep my fingers crossed for now. I will also keep tabs on this feed just to see what might happen with your issue! Thanks for all you do!
     
    fkat likes this.
  12. fkat

    fkat Junior Member

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    Prime Advanced
    It’s been 2 months since I “fixed” this issue (2500 mi), and it’s been hot here also, 90-95 daily. Fingers crossed.
     
  13. gscully

    gscully Junior Member

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    I’m having the same problem but my defroster is blowing instead of my driver vents.