2004 Tahoe LT unusual noise from rear air conditioner a/c area

[Robbie_04LTawd]

Hello--within the last several weeks, I've been dealing with a weird noise coming from the rear a/c cover area--only happens when vehicle is running and is independent of the radio being on/off, low/high volume. It also comes and goes as well--I've posted a short 20 sec video of the noise being very loud at: https://youtu.be/lq_xueH5TaY

Curious if anyone else had experienced this--any ideas where I could start? Thanks

-Robbie (04 Tahoe LT AWD, 161K miles, 1-owner)

 

[M1Gunner]

Remove the right rear trim. Unplug the blend door actuator and turn the ignition on see if the noise goes away. If it does, take the actuator off the rear hvac case and plug it back in and turn the ignition back on, listen. If the noise is still gone check the operation of the blend door. Well either way check the blend door too just verify it’s not both that have failed.