Flush AC Condensate Drain Line

The condensate drain removes moisture pulled from the air during cooling. Algae and mold grow in the standing water inside the PVC line and can cause clogs that back up into the air handler, overflowing the drain pan and potentially damaging ceilings, flooring, and drywall below. Locate the condensate drain line (a PVC pipe, usually white or grey, exiting near the air handler to the outside or to a utility drain). Find the clean-out cap — a T-shaped fitting or end cap near the air handler. Pour 1 cup of distilled white vinegar into the clean-out access and let it sit 30 minutes to kill algae. Follow with a cup of clean water. Repeat quarterly during peak cooling season. If the drain line is fully clogged, use a wet/dry vac at the exterior end to suction the clog out. Many modern air handlers have a float switch that shuts the system off when the pan fills — if your AC is short-cycling, a clogged drain is a common cause.