If my condo's A/C unit's drain clogged causing a flood in the unit below, am I liable?

Some general rules as they regard to condominiums:  unit owners are responsible for the repair of any utility that services solely their unit. Also, a unit owner will only be obligated for damage to the unit below if it can be proven that you were negligent in causing the problem.  So from your question here it apppears that what you have heard may indeed follow the general pattern in other states on these matters.  But in many states, what tends to govern in these matters is the condominium documents.  So I would start there and read yours.  And call your insurance company and send them a copy of the suit papers.  You should be entitled to a defense.  Good luck.