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Reasons Your AC Is Leaking Water

Reasons Your AC Is Leaking Water

March 25, 2025

Discovering water pooling around your air conditioner can be frustrating and concerning. An AC leak can lead to water damage, mold growth, and reduced system efficiency if not addressed promptly. Understanding the causes of an AC leak can help you fix minor issues or know when to call a professional. In this guide, we’ll explore the most common reasons your AC is leaking water and what you can do about it.

How Does an AC System Produce Water?

Before diving into the causes of an AC leak, it helps to understand why air conditioners create water in the first place.

  • Condensation Process: Your AC cools warm air by passing it over evaporator coils filled with refrigerant. As the air cools, moisture in the air condenses on the coils, just like water droplets forming on a cold glass.

  • Drainage System: The condensation drips into a drain pan and exits through a condensate drain line.

  • Potential Leaks: If anything disrupts this drainage process, water can back up and leak out of the unit.

Now that we understand how water forms in an AC system, let’s look at the main reasons it could be leaking.

1. Clogged Condensate Drain Line

One of the most common reasons for an AC leak is a clogged condensate drain line. Dust, dirt, mold, and algae can accumulate over time, blocking the drain line and preventing proper drainage.

How to Fix It:

  • Turn off your AC unit.

  • Locate the drain line (usually a PVC pipe near the indoor unit).

  • Use a wet/dry vacuum to suction out any debris.

  • Flush the line with a mixture of vinegar and water to prevent future buildup.

  • If the clog persists, contact an HVAC professional for assistance.

2. Dirty or Frozen Evaporator Coils

When evaporator coils become dirty, they can cause water to accumulate and overflow the drain pan. In some cases, extremely low temperatures can cause the coils to freeze, leading to excessive condensation when they eventually thaw.

How to Fix It:

  • Replace or clean your air filter regularly (every 1-3 months).

  • Keep your evaporator coils clean with routine maintenance.

  • Ensure your system has proper airflow to prevent freezing.

  • If the coils are frozen, turn off the system and let them thaw before restarting.

3. Rusted or Cracked Drain Pan

The drain pan collects condensation before it exits through the drain line. Over time, the pan can develop cracks or rust, causing water to leak instead of being properly drained.

How to Fix It:

  • Inspect the drain pan for cracks, rust, or holes.

  • If damaged, replace the pan with a new one that fits your system.

  • Apply a waterproof sealant as a temporary fix until a replacement is installed.

4. Low Refrigerant Levels

Low refrigerant levels can cause the evaporator coils to freeze. When the coils eventually thaw, excess water may overflow the drain pan, leading to leaks.

Signs of Low Refrigerant:

  • Weak or warm airflow from vents.

  • Hissing or bubbling sounds from the AC unit.

  • Increased humidity levels in your home.

  • Ice forming on the refrigerant lines or coils.

How to Fix It:

  • Contact an HVAC professional to inspect refrigerant levels.

  • If a leak is detected, have it repaired before refilling the refrigerant.

  • Regular maintenance can help detect refrigerant issues before they lead to bigger problems.

5. Improper AC Installation

If your air conditioning unit was not installed correctly, the condensate drainage system may not work efficiently, leading to water leaks.

Common Installation Issues:

  • The unit is not level, causing improper drainage.

  • The drain line was not connected properly.

  • Incorrect sizing of components leads to excessive condensation.

How to Fix It:

  • Ensure your AC unit is installed on a level surface.

  • Have an HVAC professional inspect and correct any installation issues.

  • If upgrading your AC, work with a trusted contractor to ensure proper installation.

6. High Humidity Levels

In areas with high humidity, your AC system may struggle to remove excess moisture, leading to more condensation than usual. If the drainage system cannot keep up, water may begin to leak.

How to Fix It:

  • Use a dehumidifier to help control indoor humidity levels.

  • Keep windows and doors closed to prevent excess moisture from entering your home.

  • Schedule routine maintenance to ensure your AC can handle high humidity conditions.

7. Blocked Air Filter

A clogged air filter restricts airflow, causing the evaporator coils to freeze. When the ice melts, excess water can overwhelm the drain pan and leak onto the floor.

How to Fix It:

  • Check your air filter monthly and replace it as needed.

  • Choose a high-quality air filter to improve air circulation.

  • Regularly inspect and maintain your HVAC system to avoid unnecessary strain.

When to Call a Professional

While some AC leaks can be resolved with simple DIY fixes, other issues require professional expertise. Contact an HVAC technician if:

  • Water continues leaking after attempting DIY solutions.

  • Your AC system frequently shuts off or cycles irregularly.

  • There are signs of mold or water damage around the unit.

  • You suspect a refrigerant leak.

  • Your system is over 10 years old and experiencing multiple issues.

At ITAK Heating & Cooling, we offer expert AC repair services to diagnose and fix leaks efficiently. Our technicians can inspect your system, perform necessary repairs, and help you prevent future issues.

Final Thoughts

A leaking AC can lead to bigger problems if left untreated. By understanding the common causes—such as clogged drain lines, frozen coils, or improper installation—you can take quick action to resolve minor issues or seek professional help when needed.

If your AC is leaking water and you’re unsure what to do, contact ITAK Heating & Cooling for fast and reliable HVAC service. We’ll help keep your cooling system running efficiently and leak-free all season long.