Typically every air conditioning system has 2 condensate drain lines. The primary line drips continually when the a/c is running. When the primary line becomes clogged (usually with algae or sludge), the secondary or emergency line will provide relief.
Most homes have their secondary a/c drain line located in the eaves of the roof in plain sight. The secondary a/c drain line for condominiums are usually located over the tub or lavatory.
Clarke Kent Plumbing can send any one of our drain techs to clear your a/c condensate drain in the event it becomes stopped up.