AC Leaks and Mold: How Your Air Conditioner Can Cause Water Damage

In Central Florida, your air conditioner pulls a surprising amount of water out of the air every day. When the drain line clogs or the pan fails, that water can quietly soak ceilings and walls and lead to mold.

Most people think of air conditioners as machines that make air cold. But in a humid place like Lakeland, an AC system is also one of the hardest-working dehumidifiers in your home. As warm, moist air passes over the cold evaporator coil, water condenses out of it, sometimes gallons in a single day during the muggy months. All of that water has to go somewhere, and when the system that carries it away fails, it ends up in your walls, ceilings and floors.

How AC condensate is supposed to drain

Water that collects on the evaporator coil drips into a drain pan beneath it. From there, a condensate line carries the water outside or into a drain. Many systems in attics also have a secondary pan and sometimes a float switch that shuts the system off if water backs up. When everything works, you never notice any of this.

The most common causes of AC leaks

• Clogged condensate lines. Algae, mold, dust and debris build up inside the line over time, especially in warm climates. When the line clogs, water backs up and overflows the pan.
• Rusted or cracked drain pans. Older metal pans can corrode and develop holes, letting water drip straight through.
• Disconnected or damaged lines. Lines can be knocked loose or crack, especially in attics where people store belongings.
• Frozen coils. Dirty filters or low airflow can cause the coil to freeze. When the ice melts, it can release more water than the pan can handle.
• Failed float switches or condensate pumps. If a safety switch or pump stops working, a backup can go unnoticed until water appears.

Warning signs of an AC leak

Because many AC units sit in attics, closets or utility rooms, leaks often go unnoticed for a while. Watch for:

• Water stains or discoloration on the ceiling, especially near the air handler or vents
• Sagging or soft spots in drywall ceilings
• Water pooling around an indoor unit in a closet or garage
• A musty or moldy smell when the AC runs
• Wet insulation or dripping in the attic
• The AC shutting off unexpectedly, which can mean a float switch has tripped

Why AC leaks lead to mold so quickly

AC leaks tend to be slow and steady, which makes them especially good at causing mold. Drywall ceilings and insulation soak up the water, and the space around the air handler is often dark and warm. Mold can begin growing within 24 to 48 hours, and because the air handler moves air through your whole home, a mold problem near the unit can spread musty odors and spores through the ductwork.

What to do if your AC is leaking

If you see water coming from your AC or a stain spreading on the ceiling below it, turn the system off at the thermostat to stop more water from forming. If the ceiling is sagging, stay out from under it, since wet drywall can give way. Move furniture and belongings out of the area, take photos, and put down towels or buckets to catch dripping water.

Next, call an HVAC technician to clear the line and repair the unit, and call for water damage drying if ceilings, walls, insulation or floors got wet. Fixing the AC stops new water, but it does not dry out the materials that are already soaked. Moisture meters can show how far the water spread, and professional drying keeps it from turning into a mold problem.

Simple ways to prevent AC leaks

• Change your air filter regularly so the coil does not freeze
• Have your system serviced, including cleaning the condensate line
• Check the drain pan and line near the air handler every few months
• Keep stored items in the attic away from AC lines and pans
• Pay attention to musty smells and ceiling stains near vents

In Lakeland, where the AC may run most of the year, a few minutes of prevention can save you from a ceiling repair and a mold problem later.