The idle air control valve in the picture below has an arrow pointing up on the back side between the two ports and I'm wondering if it should be pointing down. The valve can be put in either way.
If it were pointed down the locking tab and Volvo logo on the electrical connector would be on the top side, this alone makes me suspecious of the installation. I cannot see another connector that is installed upside down.
David

 

the arrow points in the direction of flow. it is installed correctly.