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Why Is My AC Leaking?

May 20, 2021

If water is pooling near your indoor or outdoor AC unit, you’re likely wondering what the problem is and how you can fix it quickly.

If your AC is leaking water inside your home, common causes may include:

  • A clogged drain line

  • A frozen evaporator coil

  • A damaged drain pan

On the other hand, if your AC is leaking water outside your home, it may be caused by:

  • A refrigerant leak in the outdoor unit

  • A frozen evaporator coil

No one wants a broken AC in the sweltering Texas heat, so let’s review each of these problems and help you solve them right away.

Need a pro to repair your AC ASAP? Our NATE-certified technicians can quickly figure out what’s causing your AC to leak and provide 5-star service to fix the problem.

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If your AC is leaking water inside your home ...

Cause #1: A clogged drain line

An AC unit that is working correctly will dispose of all the condensate that is collected in the drain pan by running it outside through a drain (condensate) line. The drain line runs from the air handler inside your indoor unit and is transferred outside where it is dumped out.

Sometimes, the drain line can get clogged with debris, which can cause the water to back up into the drain pan and overflow. This is problematic because it can cause drywall damage or mold may develop.

How to fix it: You can loosen and remove the clog by connecting a wet/dry vac to the outside of the condensate line (look for the white PVC pipe located near your outdoor AC unit). When you turn the vacuum on, it should suck out any debris or obstructions.

If the clog doesn’t loosen or come out, it may be located higher up in the drain line. If this is the case, you’ll need to call an HVAC technician to unclog the line.

Cause #2: A frozen evaporator coil

The evaporator coil is located above your furnace in the indoor part of your AC system and is filled with refrigerant, which is a substance that extracts heat and moisture from the air. If the temperature of the refrigerant gets too low, the evaporator coil can freeze over. Eventually, all of that ice will thaw and spill into the drain pan located underneath it, which may overflow. This might explain a puddle of water near the indoor part of your AC system.

Several different issues may cause the evaporator coil to freeze over, including:

  • Excess dirt and debris on the evaporator coil: A thick layer of dirt and grime on the evaporator coil will reduce the amount of warm air that enters the AC system. The lack of warm air passing over the evaporator coil can cause the temperature of the refrigerant inside to drop. Eventually, it may develop ice.

  • A refrigerant leak: If refrigerant is leaking out of the AC system, the overall pressure and temperature will drop, which may lead to ice developing on the coil.

  • Reduced airflow: A dirty air filter or blocked vents can reduce the amount of warm air that enters the AC system. Without enough warm air, the temperature of the refrigerant inside the coil will drop.

  • How to fix it: If your evaporator coil is frozen, you’ll need an HVAC technician to take a look. They can accurately diagnose the underlying issue and recommend the repair that’s needed to get your AC working properly again.

Cause #3: A damaged drain pan

Your AC drain pan (which is made of galvanized metal or plastic) is located inside your AC unit underneath the indoor evaporator coil. It is designed to capture condensate that forms when warm air passes over cold evaporator coils. The collected condensate flows into a PVC drain pipe that is directed outdoors. However, if the drain pan is damaged and has cracks in it, the water will just leak onto your floor.

How to fix it: You’ll need to contact an HVAC professional to replace the damaged drain pan with one that fits your AC unit.

If your AC is leaking water outside your home …

Cause #1: A refrigerant leak in the outdoor unit

Refrigerant (the substance that removes heat and moisture from the air inside your home) looks similar to water in its liquid form. A puddle near your outdoor unit might look like water but it could actually be refrigerant.

The refrigerant may be leaking from a few places, including:

  • The compressor: The pump that pressurizes the refrigerant

  • The condenser coil: The warm coil that releases heat into the outdoor air

  • One of the refrigerant lines: Two copper lines that connect the outdoor AC to the indoor evaporator coil

How to fix it: A certified HVAC professional should handle any refrigerant leaks, since the substance can be harmful to humans. Contact a professional to inspect your outdoor unit for leaks.

Cause #2: A frozen evaporator coil

If you’re seeing water pooling around the outdoor drain line, the outdoor leak could be caused by a frozen evaporator coil inside. If the coil is continually freezing over, the ice will melt and all that water will drain outside. This could be the culprit.

How to fix it: You’ll likely need to contact an HVAC professional to diagnose the root of the issue and recommend a solution.

Need an AC repair from a San Antonio tech?

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Visit our AC repair service page to learn more about our process.

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