Having trouble with the climate control system on my '87 560SEL, All pushbutton settings result in the exact same airflow pattern. 90% of all airflow is directed to the windshield and side window outlets, 10% to the foot wells. Whether air conditioning or heat the air flow pattern never changes. Anyone have any idea what the heck is going on here?

You have vacuum leak in your air condition system the center vent will not open cause air flow to the top & side vents check vacuum switch unit behind radio at right side you have to remove right side panel to test it. hope this help