Why Is My Air Conditioner Leaking Water?

As summer humidity settles over the Greater Portland area, discovering a pool of water around your indoor air conditioner can quickly cause panic. While cooling systems naturally produce condensation during operation, an active moisture leak inside your living space means something is wrong. Ignoring this dripping water can lead to severe drywall damage, mold growth, or electrical hazards. Catching the source of the leak early helps you determine if your system needs a quick adjustment or if it is time to call for professional AC repair to protect your home.

Since 1939, our team at First Call Heating & Cooling has helped thousands of Pacific Northwest families stay safe and comfortable. Understanding why your air conditioner is leaking water lets you act quickly and avoid costly property damage.

The Top 5 Reasons Your AC Is Leaking Water

An air conditioner handles an immense amount of moisture every single day. As the system draws warm, humid air across the cold evaporator coil, that moisture condenses into water droplets. Under normal conditions, this water flows down a channel and exits your home safely, but a failure anywhere along this path will result in a leak.

Here are the five most frequent reasons why water might be escaping from your cooling system:

1. A Clogged Condensate Drain Line

This is the most frequent culprit behind indoor water leaks. Over time, the dark, damp environment of the drain line allows algae, mold, dust, and sludge to accumulate. Once a blockage forms, the continuous flow of condensation has nowhere to go and quickly backs up, overflowing the internal drain pan right onto your floors.

2. A Frozen Evaporator Coil

When airflow through your system is restricted—usually due to a heavily clogged air filter or blocked return vents—the evaporator coil temperature will drop below freezing. Ice will physically wrap around the coil. When that ice eventually melts, it produces an overwhelming rush of water that easily overflows the standard drainage system.

3. A Cracked or Damaged Drain Pan

If your cooling system is a bit older, the secondary drain pan underneath the indoor coil may have rusted through or developed structural cracks. Water that should be safely funneled outside seeps through these physical cracks, forming steady puddles beneath the unit.

4. A Malfunctioning Condensate Pump

If your air conditioner or heat pump is installed in a basement or a space where gravity cannot naturally pull the water outdoors, it relies on a small electric pump to push the moisture away. If this pump burns out, loses power, or gets stuck, the water accumulation will trigger an overflow immediately.

5. Dirty Evaporator Coils

When dust and dirt bypass your air filter, they can accumulate directly on the evaporator coil. This grime blocks the condensation from cleanly dripping into the drain pan. Instead of flowing smoothly, the water becomes trapped by the dirt and drips off the sides of the coil housing directly onto your floor.

Restoring Peace and Quiet to Your Portland Home

Allowing water to pool around your mechanical systems can compromise sensitive electrical components and ruin your flooring. If you notice your system leaking, turning it off immediately and replacing a dirty air filter is an excellent first step to minimize the damage while you wait for an expert assessment.

Whenever you encounter an unexpected moisture issue, reach out to the experienced team at First Call Heating & Cooling by calling (503) 557-0962 for honest advice, dependable troubleshooting, and rapid same-day care that Portland homeowners have relied on for over 85 years.