Passenger side vents warmer than drivers side

[740iS]

Okay, I have a feeling it is one of the stepper motors, but not sure which and hope you can help out. All vents are set the same in the IHKA to cold and intensive on our 2008 4.8. But drivers side (both front and back) pumps out ice cold air while the passenger side (both front and back) the air temp is a little less than lukewarm to cool. But not cold. Any idea which actuator would or could be the culprit?

Thanks for your insight.

[absentmathis]

Have you searched the issue? This is commonly low refrigerant.

[740iS]

I'll check it again, but it seemed fully charged.