Why Is My Air Conditioner Leaking Water?

Do these three things first

Switch the system off at the thermostat. Not at the breaker, at the thermostat. This stops the coil producing more condensate while you work out what is going on, and it is the single most useful thing you can do before a technician arrives.

Contain and soak up the water. An overflowing drain pan ruins drywall, ceilings and flooring long before it ruins the air conditioner. Towels and a shop vacuum now cost less than a ceiling later.

Look at where the water is actually coming from. Water inside the air handler closet, dripping from the unit itself, points at the drain pan and the drain line. Water staining a ceiling below an attic unit means it has been overflowing for a while. Water outside at the condenser is normal and is not a fault at all.

Why this happens so often in Florida

An air conditioner is a dehumidifier that happens to also cool. Warm, humid indoor air passes over a cold evaporator coil, moisture condenses out of it exactly as it does on a cold glass, and that water runs into a drain pan and out through the condensate line. A Florida system does this for most of the year, and in a humid house it can pull several gallons a day.

That constant flow of water through a dark plastic pipe is an ideal growth medium. Algae and biofilm build up on the inside wall of the line, narrow it, and eventually block it completely. The water has nowhere to go, so it fills the pan and spills. This is not a sign that anything was installed badly. It is ordinary Florida maintenance that gets skipped until it announces itself.

The five causes, most common first

1. A clogged condensate drain line. The cause in most cases, for the reasons above. A technician clears it by vacuuming the line from the outside end or flushing it back through the access tee, then treats it so it stays clear.

2. A frozen evaporator coil that has melted. If the coil ices over and then thaws, it releases far more water at once than the pan can handle. The ice itself is the real fault, and it usually comes from restricted airflow (a filter that has not been changed, a blocked return, a failing blower) or from a low refrigerant charge, which always means a leak rather than a system that has "used up" its refrigerant. Frost on the copper line at the air handler is the giveaway.

3. A cracked, rusted or misaligned drain pan. On older systems the pan itself corrodes through. Water then leaves the unit without ever reaching the drain line, and clearing the line changes nothing.

4. A disconnected or badly sloped drain line. A line that has come apart at a joint, or one that does not fall continuously toward its exit, will pool and back up. This shows up most often after other work has been done near the air handler.

5. A unit that is not level. A pan tilted away from its drain outlet holds water on the wrong side and overflows there. Common after a system has been moved, or on a platform that has settled.

What a repair visit actually involves

A technician confirms where the water is leaving the system before touching anything, because the fix for a blocked line and the fix for a rusted pan are not the same job. The drain line is cleared and flushed, the pan is inspected for corrosion and correct fall, and the float switch is tested — that is the small safety device that shuts the system down when the pan fills, and it is the only thing standing between an overflow and your ceiling. If the coil was frozen, the cause of the freeze is chased down rather than just thawed, because a coil that iced once will ice again.

Expect the visit to need access to the indoor air handler, usually in a closet, garage or attic. EagleAir quotes a flat rate for the repair before any work begins. See AC repair and installation for what a full diagnostic covers.

How to stop it happening again

Get the drain line cleared on a schedule, not on failure. This is the single item that prevents most recurrences, and it is a routine part of a maintenance visit. Twice a year suits a Florida system, which runs close to year-round and therefore produces condensate close to year-round.

Change the air filter. A loaded filter restricts airflow, a restricted coil gets too cold, and a frozen coil is cause number two on the list above.

Make sure the float switch works. It is cheap, it is often already fitted, and an untested one is not protection.

If the house sits empty, leave the cooling running at a moderate set point. A closed-up Florida house with the system off climbs to high humidity within days and grows exactly the biofilm that blocks the line — and there is nobody there to notice the overflow. This matters most for seasonal properties in Englewood, Rotonda West and Siesta Key.

When it is an emergency

Call immediately, at any hour, if water is reaching an electrical panel or wiring, if a ceiling is sagging or stained from above, or if the air handler is sitting in standing water. Switch the system off at the thermostat and, where water is near electrics, at the breaker too.

It is not an emergency if there is a small amount of water in the pan and the system is now off — that can wait for a normal appointment. EagleAir answers emergency calls 24 hours a day across Sarasota, Manatee and Charlotte counties on (904) 316-9933.