'99 E300 CCU Synchronization ???
 

Is it possible to synchronize the two sides of the CCU ? I find it terribly annoying to have to adjust "both" sides to regulate cabin temperature.

Not possible as far as I know. It's a pretty nice feature to have 2 independent controls. I've noticed that my pasengers who are used to manual controls tend to fiddle with the temp WAY more than they need to. Adjust the temp up or down a degree at a time then wait a couple minutes before making another change.

I leave mine on 72 year around. The only things I tend to adjust are the air director controls. I like to have warm legs in the Winter so I send all the heat to the floor unless I'm trying to defrost.

And remember, when your passenger does play with the setting, pressing both up and down at the same time resets the side back to 72F.