Who to serve papers to at a condo association?

I am a process server chiefly in the County of Cook, State of Illinois. We have been given the additional problem of determining who to serve on behalf of the condominium association. It would seem easy to simply ask the residents in any given complex to whom they make assessment payments, but that isn't as easy as it may appear. People who will tell you how long they've been out of work, why they're getting divorced and how much they had to pay to get their kid out of jail will balk, look at you as though you were putting your hand in their pockets and almost universally decide you are running a scam of some sort if you ask how to contact their condo association. Is there some kind of website that conveys this information?