Your air conditioner does two jobs: It cools down the air and it dehumidifies the air. If you live in a dry climate, you want the AC to dehumidify as little as possible because it uses extra energy and makes you spend more on lip balm and hand lotion. If you live in a humid climate, you really want it to do that second job as well as it can to keep your indoor air dry and comfortable. But where does all that condensate go?
In most homes, it goes outdoors through a pipe, like the one above. Sometimes there’s a little pump that pumps it out, but most often it drains by gravity alone. Occasionally that condensate line gets clogged. This happened at my condo last week. (We live in Atlanta, Georgia, a mixed-humid climate.) Gunk in the pipe built up to the point where it was barely draining. We could run the AC for a little while and then we’d have to turn it off again.
Source: How to Clean Out Your Air Conditioner’s Condensate Line