Vent? Above drivers head.

[MC87SS]

Hello everyone.
Just picked up an 04 Tahoe and have a question.
There is what appears to be a vent above the drivers head in the headliner and it is making a noise that is driving me crazy.
Can anyone tell me what it is and how i can fix the noise.

Thanks in advance.

 

[Repo503]

Microphone for onstar...probably has some electrical interference.

 

[HMFDZ28]

Been covered...http://www.tahoeyukonforum.com/forum/showthread.php?t=4859&highlight=climate

 

[MC87SS]

Thank you for the information.
I did a search but came up empty.
I will be fixing this tomorrow.