I have a 92 400e and suffer the same problem. I guess I'll have to check the filter as well. But I do have to say that I am no a fan of the ACC! I don't like having only 2 fan speeds to manually chose from. This is the ONLY car I've ever been in that restricts you in this way. What the F***! Are the German engineers really such control freaks? Futhermore I do not like the fact that the ACC determins when air will come out of what vents IT chooses. To futher rant on - I hate how long it takes for the ACC to change air temp when adjusting the temp dial. To me, the functionality of the ACC is one of the things I think really tops the list in what is sub-par in the W124 (don't get me wrong, overall the W124 is a great car). Am I the only one who feels this way?