What to Do When Your AC Leaks Water

Water on the floor by your indoor air handler is a problem you want to catch early. Most of the time it is not a disaster. But left alone, that slow drip can soak drywall, rot a subfloor, and grow mold in a closet you rarely open. Here in Mount Gilead, our long humid summers make this one of the most common calls we get. Your AC pulls a lot of moisture out of the air, and all that water has to go somewhere.

This guide walks you through what to do the moment you spot a leak, what is usually causing it, and how to tell a quick fix from a real repair. Read the first section first. The rest can wait until the water is under control.

Do This First: Stop the Damage

Before you go looking for the cause, protect your home and your equipment.

• Turn the system off at the thermostat. Set it to "Off," not just a higher temperature. Running a leaking unit keeps making water and keeps feeding the leak.
• Flip the breaker if water is near the electrical. If you see water dripping onto the air handler's wiring, control board, or the disconnect box, shut the unit off at the breaker. Water and electricity do not mix.
• Mop up standing water and pull anything valuable out of the way. Boxes, carpet, and stored items soak fast.
• Put a bucket or shallow pan under the active drip if it is still coming. A few towels under the air handler help too.
• Check the secondary drain pan. Most attic and closet air handlers sit in a metal or plastic safety pan with its own drain. If that pan is full, the main drain is already backed up.

Once the water has stopped spreading, you can figure out why it happened. A short, controlled shutdown will not hurt your system. Running it while it leaks will.

Why Your AC Leaks Water in the First Place

Your air conditioner makes water on purpose. Warm, humid Piedmont air passes over the cold evaporator coil inside your air handler, and moisture condenses on the coil just like it does on a glass of iced tea in July. That condensation drips into a pan and runs out through a drain line, usually a white PVC pipe, ending outside or at a floor drain.

When you see a leak, that normal process has been interrupted somewhere. Here are the usual suspects, roughly in the order we find them.

The Most Common Cause: A Clogged Condensate Drain Line

Eight times out of ten, the problem is a plugged drain line. The pipe carrying water away from your unit gets blocked by algae, slime, dust, and gunk. Our humidity makes this worse than almost anywhere, because the line stays wet and warm all season, and that is exactly what algae loves.

When the line clogs, water backs up into the drain pan, overflows the pan, and ends up on your floor or your ceiling.

What you can check yourself:

• Find the drain line where it exits the air handler, a small PVC pipe, often with a T-shaped fitting and a cap on top.
• Look at the outdoor end. A healthy unit drips water outside while it runs. If the inside is leaking but nothing comes out outside, the line is blocked.
• Try a wet/dry shop vac on the outdoor end. Hold the hose tight over the open pipe and run it for a minute or two. This can pull the clog free and is the single most useful thing a homeowner can do.

A backed-up line is exactly why we recommend a yearly cleaning. A clear drain and a small dose of treatment in the line during a tune-up prevents most summer leaks before they start. Our seasonal AC maintenance visit includes flushing and treating that line.

A Frozen Coil That Melted

If you found a sudden flood of water, not a slow drip, your evaporator coil may have frozen and then thawed. A block of ice forms on the coil, the drain pan cannot keep up when it melts, and water pours over the edge all at once.

Coils freeze for a few reasons:

• A dirty air filter choking airflow. This is the most common cause and the easiest to fix.
• A blocked return vent or closed supply registers reducing airflow.
• Low refrigerant from a leak in the system.
• A failing blower motor not moving enough air.

If you suspect ice, turn the system off and switch the fan to "On" at the thermostat. Running the fan without cooling helps the coil thaw faster. Then change your filter. If the coil freezes again after that, the cause is deeper, low refrigerant or an airflow problem, and you need a tech to check it. Do not keep running a unit that freezes. You can damage the compressor, and that is an expensive part.

A Dirty or Clogged Air Filter

A filter packed with dust does more than freeze coils. Restricted airflow drops the coil temperature, which leads straight back to ice and overflow water. Pull your filter and hold it up to a light. If you cannot see through it, replace it.

Change filters every one to three months during heavy cooling season. Homes with pets, lake-area pollen, or a lot of dust need them more often. A clean filter is the cheapest preventive maintenance you own.

A Cracked, Rusted, or Misaligned Drain Pan

The drain pan under your coil catches condensation before it hits the line. Pans corrode over time, especially in humid and lakeside homes where the metal stays damp for months. A pan with a rust hole or a crack will leak even when the drain line is perfectly clear.

This is common in older systems. If your unit is fifteen years old and the pan is rusted through, a new pan is a fair repair, but it is also a sign the whole system is near the end of its life. We will tell you honestly which way to lean.

A Disconnected or Improperly Sloped Drain Line

Sometimes the line itself comes loose at a joint, or it was never sloped correctly during installation. Water needs gravity to drain. A line that runs flat or uphill will pool and back up no matter how clean it is. If your leak started right after a new install or a recent service, this is worth a look. It is a workmanship issue, not wear and tear.

A Full Condensate Pump

Not every home drains by gravity. If your air handler sits in a basement or somewhere below the drain exit, a small condensate pump moves the water up and out. When that pump fails or its float switch sticks, water has nowhere to go and overflows. Listen for the pump cycling. If it is silent or the reservoir is full, the pump likely needs service or replacement.

When to Call a Professional

You can safely handle a filter change and a shop-vac on the drain line. Call a tech when:

• The drain line will not clear with a shop vac.
• The coil keeps freezing after a fresh filter.
• You see oily residue or hear hissing, possible refrigerant leak.
• The drain pan is cracked or rusted through.
• Water reached the electrical components or the control board.
• The leak comes back within a day or two of your own fix.

A refrigerant problem in particular is not a DIY job. It takes gauges, EPA-handled refrigerant, and leak detection to do right. If your system is short on refrigerant, the leak that caused it has to be found and sealed, not just topped off. Our AC repair team handles diagnosis and the fix in one visit when we can.

If your home is one of the older houses near historic downtown without much ductwork, or an addition that never cooled well, sometimes the real answer is a better-matched system. We will talk through whether a repair or a ductless mini-split makes more sense for your space, no pressure either way.

How to Prevent the Next Leak

A leak you never have to mop up is the best outcome. A few habits keep your drain clear all summer:

• Change your filter on schedule, every one to three months in cooling season.
• Keep the area around your outdoor unit clear of leaves and grass clippings.
• Pour a cup of distilled white vinegar down the drain line a couple times a season to slow algae growth. Skip bleach, it can damage some fittings over time.
• Watch your secondary drain pan. Standing water there is an early warning the main drain is struggling.
• Book a tune-up before summer. A spring visit clears the line, checks the coil, and catches a rusting pan before it floods your closet.

Humidity is the quiet stressor on every system in Montgomery County. Long compressor run-times mean more condensation, more drain-line algae, and more corrosion on outdoor units, especially out toward Lake Tillery. Staying ahead of it with maintenance and clean filters is cheaper and easier than chasing leaks. If poor air quality or a musty smell came along with the water, our indoor air quality work addresses the humidity behind both.

Call EM Contractors LLC in Mount Gilead

If your AC is leaking and you cannot stop it, or you cleared the line and it came right back, give us a call. EM Contractors LLC has been the Mabe family's local heating and air business since 2005, right here in Mount Gilead. We will find the real cause, explain it in plain language, and charge a fair price for the fix. No upsell, no scare tactics, just honest work from a crew that lives and works in Montgomery County. We serve homes and businesses across Mount Gilead, Troy, and the surrounding towns, often same day when we can. Call us and we will get your system dry and cooling again.