I think something is not working right. When I push the right-mopt "O" button, ecerything shuts off and stays off - fan, compressor, the works. Pushing the E button to the immediate left shuts off the compressor, but lets the blower fan circulate air. The center button with 1 black up arrow and a white down arrow is the normal operating position. The button to the left of that with 2 white arrows is for use when the interior starts to slightly fog up, and should be switched back to the center button after the interior is clear. The left most button is the major defog button, and pumps hot air out the defrost vents. If you have an owners manual, it goes in to greater depth about how the buttons control different vents under different conditions, and gets a little complex, but O is supposed to be everything Off.
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