Buzzing Noise

[MassHoe04]

you can pull the hvac fuse as well to see if the noise goes away, when you put the fuse back in and turn the key on it will do a self calibration

I'll give that a try too. When I was playing with my Tech 2 a couple weeks ago, I did get into the menu that does recalibration. That recalibration had no effect, but I'll see if pulling the fuse confirms the source.

 

[Rocket Man]

I’m betting it’s an actuator. My 02 made a noise similar to that only not as loud. They go through a reset procedure every time the engine is started even if the system is off I believe.

 

[SheniqueTheDenali]

This sounds like the same problem a friend of mine had with her 2006 Impala. Hers made the same sound and it was the blend door.