Condensate drain

As the indoor coil dries the air, the water it collects runs out through the condensate drain line. In humid coastal UAE that is a surprising amount of water, and a drain blocked by dust or algae is the number-one reason an AC drips onto the floor or stains the ceiling below. Clearing and flushing the drain is routine maintenance; a permanently wet patch usually means the line is clogged or wrongly sloped, not that the unit is broken.