The AC on my 300E was not very intuitive - I had to read the manual to correct some wrong assumptions on my part. My controls had a defrost, EC, and O button which I figured out correctly. The remaining 2 buttons each had arrows pointing up and down. I assumed the one with the black up arrow and white down arrow meant "Heat or cool the feet area", and that the button with 2 white arrows meant "heat/cool all areas". Wrong! Turns out that the first one means "normal operating position", and the 2 white arrows mean "temporary position to dehumidify windows, switch back to normal (black and white arrow)position when clear"!!! I wonder if something similiar is going on with your controls.
2003 Firemist Red/grey leather SL 500
2015 Palladium Silver/black mbtex GLK 350
1987 Smoke Silver/burgundy mbtex 300E Sportline (SOLD)
Click to see 87 300E