2020 Silverado Blend Door Noise

[Crone9]

2020 Silverado RST with 14500 miles, bought new last April.  The blend door makes an audible noise when opening and closing.  It happens at stop signs when engine shuts down and when pressing the recirc button.  Best description of the sound is similar to imagining a golf ball in the vent 'thunking' each time the blend door opens/closes.  GM tech said its normal and all trucks make that noise, and there is nothing to be done.  Can anyone out there confirm you hear a knock or thunk every time the blend door operates?

[Adamace1]

I hear it in auto mode the most. It seems in auto it opens and shuts alot more. This is the loudest blend door I have ever had on any of my cars. It's just louder than I'm used to.

[Anacortes Army Guy]

17 hours ago, Crone9 said:

2020 Silverado RST with 14500 miles, bought new last April.  The blend door makes an audible noise when opening and closing.  It happens at stop signs when engine shuts down and when pressing the recirc button.  Best description of the sound is similar to imagining a golf ball in the vent 'thunking' each time the blend door opens/closes.  GM tech said its normal and all trucks make that noise, and there is nothing to be done.  Can anyone out there confirm you hear a knock or thunk every time the blend door operates?

Mine does not make a noise as you describe, and operates very quietly.  Read this article and see if it applies in your case:

 

 https://wrench.com/blog/what-is-a-blend-door-actuator-and-how-do-i-know-if-i-need-a-new-one/