I live in a condo with an HFAC unit. In the last two weeks, I have had flooding in my unit, and damage has also occurred in the two units underneath me. I believe I have figured it out - the janitorial services put a plastic tube from my condensation outlet tube to the drain pipe, and there is tremendous force of water when it rains. It rained hard twice in the last two weeks and twice, I have had flooding in my unit. At first, the janitor claimed it was the condensation (I wasn't in the US at the time)l. I dismissed it, until it happened again when I was in the unit. It was only then that I realized the plastic tubing. Another theory is water coming over the gutter, but this has happened before and not caused flooding. And I would have noticed that, since I was here on an early sun morning during the rain. What do you think? thanks.