1981 Mercedes Benz 380sl Cabin cooled air

I have the Service Manual, Heating, Air Conditioning, Automatic Climat Control, Model 107. In Section 83-600, B. Control Unit-AUTO-LO reference is made in the second paragraph, line 4 of that section to ".A leak share from defroster jets." With no leak after August 1978. On the car referenced above I do get cooled air coming out of the defroster vent, it appears that I should not.

My VIN is: WDBBA45A4BB001219 ON PILLAR POST
WDB10704512001219 ON X- FRAME ABOVE THE RADIATOR

My question is: is it correct to have cooled air coming out of the defroster vents on this car? The question is important because I have converted to R134a which idoes not cool as effectively as the original R12, and cooled air coming out of the defroster vents is warmed by the heat on the dash, and that combined with the less effective R134a results in the cabin being not as cool as one would like. FYI the compressor was rebuilt and the condenser rebuilt, so all elements of the system should be OK, except I don't know about expansion valve as it is difficult to get to. Your comments please.

Also I have spent considerable time studying the Function Diagrams for example Diagram 2 83.1-604/3, I have a difficult time understanding how the Main Air Flap, Item 42 functions. I understand that they are dual elements, but looking at Function Diagram 2 and Funtion Diagram 6, I do not see any difference in the interanl positions of eith element. Your guidance please.