Defroster Humming Noise

[Borntorun]

Recently my 2024 GMC Sierra Denali has an annoying humming noise when my defroster is on high speed fan. There is no noise when heater is on using dash or floor vents with high fan speed. I took it to dealer and they figured out that the actuator doors are vibrating and thats what is making the noise. They said there is a Preliminary Bulletin on problem. They say they will need to remove dash and install flocking tape by actuator doors to stop vibration sound. I’m wondering if any member had this problem and had this repair done. I’m concerned about them removing dash and reinstalling dash . Concerned I might have future problems from having dash removed and reinstalled . If sound wasn’t so annoying or if I lived in an area where I didn’t use defrosters much I might just deal with noise and skip repair. I don’t know how to post bulletin but here is info if someone wants to look up and view for more info. Preliminary Bulletin PIT6132B . Dealer had to order material / parts for repair so it’s giving me time to think things over. Thanks in advance for any reply’s! 

Edited November 6, 2025 by Borntorun

[davester]

It depends on the person/people doing the work.  The job is removing a bunch of nuts/bolts/screws/connectors/clips, then reinstalling those nuts/bolts/screws/connectors/clips.  They either do it all correctly and carefully, so trim clips don't get busted off, screws are tightened enough, parts are lined up right, or they don't.  This attention to detail will vary with the dealership and even the individual doing the work.

[Borntorun]

Thanks divester for your thoughts ! The more I think about it the more I think I might just pass on tape repair  job ! My thinking now , Deal with a noise during winter where most of the time when defroster are on high will be when I use remote start and not in truck . When in truck heat might be blasting but there’s no noise with heat out of vents dash or floor. Or deal with potential rattles or something else not working after dash removal and reinstall. Answering is becoming more clear at least in my mind . Skip job with dash removal. 

Edited November 7, 2025 by Borntorun