From my searching this site I see we are not alone by any means. And, it is not specific to C-class either. Problem is, I cannot find anyone who has described the fix. Often these complaints go unanswered. It's time to get busy and find the remedy.

I invite anyone who reads this, who is motivated by a similar problem, to help by doing their own search. I've been unsuccessful using words like: "w202 AND climate control AND air vent AND PSE pump."

Wouldn't hurt to also try www.mbworld.org and others I may not be aware of.