For those of you in cooler climates you may not be able to appreciate this unless you climb into a sauna fully dressed and then go to work for the day...
I've spent all week climbing into a car that's been blasting me in the face with scolding hot air all week. It's been in the mid 90's and the temp reading in the 100's when I get into my car. It's in the upper 80's right now. (the best time to work on the car is at night) With the AC on I was getting cold air out the center while hot air out the top. What a tease that was. I found that having the windows down and the sunroof open was more efficient.
After doing some reading on alldata I searched around and looked up the heat control valve that carson356 mentioned and came up with some adjustments.
I found this:
Adjusting Mixed Air Flaps
NOTE: For this heating system the heater output is controlled by the position of the mixed air flaps and not by the position of the water valve in coolant circuit.
Open fresh air flap. Set control switch for heater to position "open". Set adjusting screw in such a manner that the mixed air flaps are tightly closing in position "max. heating".
I pulled out the 4mm and adjusted the center flap by two full turns in and all started working as expected. I can hear the flaps inside moving, the air shifts from top to center as expected.
It is for this reason that I really love MB...
In my experience, it's always something simple.
Thanks for all the replies!