Speaker or fan
 

I have a 2003 Z71 What is that fan like noise I hear coming from what looks like small speaker in the headliner over the drivers "seat." Any ideas?

My '04 Silverado Z71 also does this. What I can tell you is that is the speaker for the OnStar system. Why it makes a buzzing noise it beyond me. I haven't gotten into finding the root cause of it just yet, because eventually the noise on mine goes away after a few minutes or if I key off and back on a time or two.

EDIT: whoops, I was wrong. That noise is from a small fan in there that sucks air onto the cabin temperature sensor for the auto HVAC functions. So ... it's normal I guess. I'm going to look into replacing my fan so it isn't noisy anymore.

Heh, Thanks Man. I thought it was a speaker until I noticed it kept going after I shut off the key.

Yeah it's definitely a fan. Look's like it's going to be quite the project to remove the headliner to repair it. Thanks for the info..

Honestly it doesn't seem like you'll need to remove the whole headliner to replace the fan. Seems like if you pull the driver side A and B pillar trim, the driver side sun shade you should be ale to get the headliner down far enough to swap it out. As far as I know, it's just clipped in place.