96 E320 Loud High Pitch Noise on cold start

[gatsu]

Hi guys,

I own a 96 e320 here in hawaii and this noise happens everytime on a cold start.
Has been now for the past 2 months. It's a loud high pitch whirring/squeal (like a mini siren) and after 45 secs it goes away. For example, in our community we have the siren that lets us know if theres some kind of warning (war or disaster), the noise comes on, whines, and then when it shuts down it dies down like the siren does (i hope that was a good analogy haha). It usually comes back again for maybe 5 seconds once the car goes back to idle (like if i start it and take off, at the next traffic light itll come back on for less then 5 secs). The noise will not come back at any other time unless the car sits for hours before the next start.

I know it's not a drive belt. I'd think its some kind of pulley or bearing but the type of sound it is and then cycles off within a minute doesn't seem right. I've given up and now see if someone else has dealt with this issue before. I best guess is some kind of vaccum or ac noise. All components on car works fine and nothing changes the pitch or length of the sound while doing anything (turning ac on, driving, etc)

Thank you for your time.