Both the 300D and the 190E that I had blow fresh air through the center. The side vents blow heated air. With the A/C on, all vents blow air through the cores. (I believe they are in the same air path)
I too, have a problem with my 190E now where it blows hot air through ALL the vents now. The A/C does cool it marginally. I have not had time to check the vacuum system for leaks yet as I am in the middle of taking the engine out. (Bent valves due to broken timing chain)
