I'm trying to help my neighbor figure out what this noise on his 2004 V70 turbo is. It's a loud shriek that is usually heard when the AC is on, and occasionally even after the engine is turned off (key out of the ignition).

The video was taken by a family member who must have thought the sound was coming from somewhere on the right side of the engine bay.

Ideas?

Link to video of noise

 

I know this is an old thread but I'll go for it sounds like the alarm has gone south shorting out . The siren is located right behind passenger head lamp and I bet the board in side is shot.

 

Thank you! I'll let you know if that ends up being the issue.

 

I second that diagnosis but if it tails off 10 minutes after shutdown it might be the refrigerant gas equalizing.

 

engine cooling fan always runs when the AC is on, it continues to run after engine shutdown to prevent heat soak under the bonnet.