I still might try to find a manual system from a 240D, but I have never liked Mercedes's approach to HVAC. The Japanese companies have always had a better approach, a point that I first noticed this back in high school when I bought an early 70's Dodge Colt (made by Mitsubishi). The ventilation system was everything you need to control the environment in a car. It was simple, flexible, and effective.

As poorly designed (in my humble opinion) as the Mercedes manual systems are, I think that their automatic systems are even worse. For that matter, I don't see why anyone would want automatic climate control in a car. There are too many variables that the automatic system can't control. All the system knows is cabin temperature and whether the occupant wants defrost, or bi-level, or whatever air distribution. Human comfort is affected by numerous other variables that the system can't control such as the level of sunlight coming in, humidity levels, whether the windows are open or closed, and probably other factors that don't come to mind right now. To me, a manual system gives the highest comfort level. Part of why I think that is the psychological benefit of being able to tell the system what to do rather than depend on an automatic controller to figure it out.

My plan is use the HVAC control unit from a junkyard Honda Accord. If it works, I will post pictures. If it is a debacle, I will disavow any knowledge of this thread.