Need help with ACC vacuum line identification.
 

Somehow in the excitement of replacing pods, connectors, changeover valves, etc. during my ACC adventure, I lost track of where this line goes. It's red with blue stripe and approx. 28 inches long. There is already a red/blue line attached to the red/blue fitting on the changeover valve. Any ideas where this one goes? Thanks in advance. 83 300SD

My pictures from my dash out on my w123 dont have great detail, but assuming your 126 is similar, and if memory serves, there should be a line between the defroster pod and center vent, with a Y fitting at the center vent. I would check there.