I work in construction management and have some experience with HVAC condensation leaks, but am by no means an expert. Where is the unit located in the house?... attic, basement, crawlspace? Does it have a condensate pump? How old is the house/HVAC unit? I've seen condensation leaks from the following reasons and yours may or may not be one of these:
-Broken condensate pump (or tripped circuit breaker)
-Condensate drain lines installed on wrong drains (most units have 2 drains, one for vertical unit installation (basement) and one for horizontal unit installation (attic or crawlspace)
-Faulty dampers inside unit (may be sticking)
Your unit should also have a service manual. If your house is relatively new, they are usually left near the unit by the installers for future service referencing. If it is an old unit, you could try to find it on the web, but good luck. If you can find this manual, you may be able to troublshoot it. Otherwise, you'll have to do more exploring or call an HVAC tech to look at it.