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Why Is My AC Leaking Water Inside My Home? A Texas HVAC Pro Explains

May 21, 2019

If you see water leaking from your air handler (the indoor part of your AC system), then it usually means you have one of the following issues:

  • Clogged condensate line
  • Rusted drain pan
  • Frozen evaporator coil

We’ll go into each of these issues in more detail. But first, let’s look at why your air conditioner produces water in the first place...

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Why your AC produces water in the first place

Inside the air handler (the indoor part) of your air conditioning system, there’s a component called the evaporator coil, which is the part of your AC that pulls heat out of your home’s air.

Evaporator Dehumidification Process Healthy With Waves

Here’s how it works:

Your AC pulls in warm air from your home. That air moves across the cold evaporator coil, where heat is absorbed from the warm air. Once that heat is absorbed by the evaporator coil, the now cool air is blown back into your home.

During this cooling process, water (condensation) forms on the evaporator coil, similar to the beads of water that form on a glass of cold water on a hot day.

Normally, this moisture collects in a drain pan and then flows outside via a condensate drain line.

However, if you have one of the issues below, this water can leak out of your AC and into your home.

Let’s look at how to troubleshoot these problems...

Problem #1: Clogged condensate line

Like we mentioned above, the moisture collected by your AC should normally drain out of the condensate line.

But if your condensate line is clogged with dirt and debris, the water can’t exit your home. It will collect in the drain pan until it overflows.

Evaporator Dehumidification Process Blocked

How to fix the problem: Contact a professional to clear the drain line. They will use a special vacuum to suck out all of the debris.

Problem #2: Rusted drain pan

Drain pans can rust over time. If your AC drain pan is severely rusted, it can form a leak, and the condensation that drains from your evaporator coil can leak out of the pan. This could explain the water leak you’re seeing.

How to fix the problem: If your drain pan is leaking, it needs to be replaced. If you know the dimensions of your drain pan, you can go to a home improvement store and purchase a new one. Otherwise, contact a professional to replace your drain pan for you.

Problem #3: Frozen evaporator coil

If your evaporator coil gets too cold, it can cause the moisture that collects on the coils to freeze. When the ice eventually melts, the drain pan can overflow, causing water to gather around your air handler.

In addition to possible water leaks, a frozen evaporator coil also raises your energy bills and reduce the performance of your AC system.

What causes your evaporator coil to freeze?

The most common causes of a frozen evaporator include:

  1. A dirty air filter: A filthy air filter blocks warm air from entering your AC system. If the evaporator coil can’t get enough warm air blowing over it, it will freeze.
  2. Closed/blocked air vents: Similar to a dirty air filter, closed/blocked air vents restrict airflow into your system, which could cause the evaporator coil to freeze.
  3. Refrigerant leak: Your evaporator coil uses refrigerant to remove heat from the warm air. If refrigerant levels drop too low, the coils will get cold and start to freeze. If you have low refrigerant levels, this means there’s a leak somewhere in your system. Since refrigerant is a potentially harmful substance, only a professional should find and repair any refrigerant leaks.

How to fix the problem: Change your air filter (if it is dirty) and make sure your vents are open. If the leaking water persists, contact a professional for help. They will check your refrigerant levels and find what else could be causing your AC to leak water inside.

Need AC help from a San Marcos pro?

No matter what type of air conditioning repair you need, our trusted techs can handle any job. All of our technicians follow the highest industry standards and offer world-class customer service for every repair.

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