HVAC making noise

2008 DODGE CARAVAN
111,000 MILES • 3.8L • 6 CYL • 2WD • AUTOMATIC
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HADAVIS
  • MEMBER
  • 2 POSTS
rhythmic knock in area of heat/AC blower in cold weather-mn-sys locks in floor heat position then will blow dash vents after knock stops-20-30 seconds. when fan is in re-circulate knock stops immediately no other electrical issues.
Jan 22, 2022 at 9:20 AM
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KASEKENNY
  • AUTOMOTIVE REPAIR CONTRIBUTOR
  • 18,907 POSTS
This sounds like a door actuator that is running through the calibration, but I would like to try and hear the noise before we are sure of this.

However, if I am correct, we are going to have to figure out which door.

https://www.2carpros.com/articles/replace-blend-door-motor

I am attaching the info below to show the locations but the best way to figure this out is touch each actuator when they are knocking, and you will feel it on whichever door it is coming from.

Please see the locations below. If you have dual zone temperature control, then you have two blend doors.

Let's see if you can start with a video and then you will need to access the actuators and start the vehicle to get them to do it and see which is making the noise. Clearly, I would not want to have you do this until I can be sure this is the noise, I am thinking it is.

Thanks
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Jan 22, 2022 at 2:36 PM
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HADAVIS
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Thanks, i appreciate your help.
Jan 22, 2022 at 2:44 PM
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KASEKENNY
  • AUTOMOTIVE REPAIR CONTRIBUTOR
  • 18,907 POSTS
You are welcome. Please let us know how this turns out. Thanks
Jan 22, 2022 at 6:46 PM