When the blend door actuator recalibration makes things WORSE(!?)

Discussion in 'Interior' started by Z71Tahoe2004, Nov 24, 2018.

  1. Z71Tahoe2004

    Z71Tahoe2004 TYF Newbie

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    After noticing that my driver side blend door actuator (the one that controls air direction - floor, front, defrost) had stripped gears, I installed a new actuator. I plugged it into the wiring harness and performed the re-calibration procedure (pulling and replacing the fuse, turning the electricity on and off, etc.) After I recalibrated it, there's a new problem. When I turn the engine on, the actuator cycles through the range of motion before stopping on defrost. It won't respond to A/C head unit controls. I've replaced a few BDAs before and never seen this happen. The A/C head unit was replaced with an AC Delco OEM part just a few months ago. Everything was good before the recalibration. Anyone seen this before or have any idea how to fix this? Thanks!
     
  2. swathdiver

    swathdiver Full Access Member

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    There are internal BCM codes that explain which door failed and why.

    Alternate Method (w/o Scan Tool)
    1. Clear all DTCs.
    2. Place the ignition switch to the OFF position.
    3. Install the HVAC actuator.
    4. Connect all previously disconnected components.
    5. Remove the HVAC/ECAS fuse for a minimum of 10 seconds.
    6. Install the HVAC/ECAS fuse.
    7. Start the vehicle.
    8. Wait 40 seconds for the HVAC control module to self-calibrate.
    9. Verify that no DTCs have set as current DTCs.
     
  3. Z71Tahoe2004

    Z71Tahoe2004 TYF Newbie

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    Thanks Swathdiver. That's the recalibration technique I used initially. When I restart the engine after replacing the fuse, the actuator actually cycles all through all the door positions before stopping on the defrost position. Once that initial cycle takes place, I can't adjust the position. So it's not that the actuator isn't getting a signal from the head unit. It's just that it won't respond after that initial cycle. Oddly, it cycles through every time I start the ignition, but again, it won't come off defrost once it stops there. That full cycle never happened when starting the ignition before the recalibration steps taken today...
     
    Last edited: Nov 24, 2018
  4. swathdiver

    swathdiver Full Access Member

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    Duplicate post.
     

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