Weird sound at the start of AC

[cober]

Hey guys!
Noticed strange noise when I start the engine and turn on an AC.
It's like creaking from the bottom of a truck. Not from under the hood - it's really weird.
And it disappears after 30 sec or so...
Who experienced this kinda sound? What is this?

 

[C420sailor]

I had a loose exhaust heat shield that would rattle like that with the AC on, in gear. If the RPM varied, it would get better/worse

Check your shields