noise from center of dash

Hey guys new to the forum and looking for some help. After I shut off my truck I hear a noise coming from the center of the dash that sounds like a hard drive or small motor of some kind running for maybe 30 seconds or so. Sometimes I notice it when the truck is sitting still and engine running. Can't pin down exactly when or what is doing it and wondering if any of you have an idea.
Thanks,

My silverado makes the same noise and i think it may be the cd player. when yours makes this noise , is there a cd in the player even if it is on radio. I usually have a cd in the player all the time even when i am only listening to the radio, i will have to take out the disk and see if it still makes the sae noise.

No I didn't have a CD in..Thought about that earlier. Sounds like it is behind the radio in that general area...don't know what else would be back there. Sounds like some kind of little motor.

Sure it's not the fuel pump? cuz mine will run for about 5-10 seconds after i shut it off. I have heard of alternators going bad and making a surging sound on shut off....doubtful for that but also remember not every sound is bad.

it is the cd player mine does it too. why, i dont know but i havent noticed any ill effects though. it dont make that noise very long though either.

I was told it is a fan on the back of the radio due to the heat and confined space.

That might be it...kinda sounds like a fan running right behind the radio!!!!Didn't know there was a fan back there.

fan makes sense......first i have heard that bet it does get hot under there though.

fan makes sense......first i have heard that bet it does get hot under there though.
That is right....There is a fan attatched to the back of the radio. It is in plain sight if you have the radio out