Greetings,

Somewhere from the late 70s into the early 90s MB used a 5-button with red/white/blue thumb wheel as the the climate control unit (CCU). The air is then directed to either the feet, defroster, center and/or side vents. The w210s and later w140s I have seen have a newer unit with separate left/right settings and an LCD display that often fails.

I was in my friend's w140 yesterday and when I turned on her car air was being discharged from her various vents including her center vent. That got me to thinking, "I can't remember air coming out of my (the older 5-button CCU) center vent unless I put the temp wheel on min and the push-button on EC."

Are there other settings/conditions that result in air being discharged from these older CCU besides the one setting I describe above?

Thanks.