Why Is My AC Leaking Water? A San Antonio Tech Explains

March 17, 2020
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Do you notice water pooling around your AC unit? Don’t wait for it to get worse.

A leaking AC is a problem that needs to be addressed quickly in order to prevent any significant damage to the inside of your home.

Some of the issues that can cause your AC to leak inside include:

  • A clogged condensate drain line
  • A frozen evaporator coil
  • A cracked drain pan

Below, we’ll go through each of these issues in more detail to help you pinpoint exactly why your AC is leaking water and what you can do to fix it. Want a professional to troubleshoot and repair your AC system for you? Just ask!

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A clogged condensate line can cause your drain pan to overflow and eventually leak inside your home.

During normal operation, your AC draws in warm, humid air and removes the heat and moisture from that air. All that moisture is collected in the primary drain pan (a galvanized metal or plastic pan that sits inside your inside AC unit).

The moisture is then transferred out of your home via the condensate line (a white PVC pipe), which finally dumps the moisture outside.


Your AC during normal operation

If the condensate line becomes clogged, the moisture that your AC has collected from the air will begin to back up in the drain pan. This clog can cause your drain pan to overflow, spilling water onto the floor around your indoor AC unit.


A clogged condensate line

The solution: How you go about handling the clog all depends on its exact location in the pipe. For example, if the clog is near the end of the line, it can be cleared with ease.

A condensate drain line

To unclog your condensate line, follow these steps:

  1. Get a wet/dry vacuum.
  2. Find the condensate drain line (pictured above) outside your home.
  3. Connect the vacuum to the end of the condensate drain line and turn it on.

The vacuum should suck out any debris or obstructions that may be clogging the line.

However, if the vacuum is unable to suck out any debris, the clog is probably higher up in the condensate line. In this case, you’ll need a professional to unclog it for you.

If your evaporator coil is frozen, the ice that has developed on the coils will thaw between cooling cycles, causing water to leak in your home. Your evaporator coil is located inside your indoor AC unit. The evaporator coil itself is an A-shaped web that’s made up of smaller, copper coils. These smaller coils are filled with a substance called refrigerant (a heat transfer fluid).

An example of an evaporator coil

With the help of the refrigerant, your evaporator coil works to cool the air inside your home. As the warm air from inside your home blows over the cold coils, the refrigerant absorbs the heat from the air. Your AC system now has cool air blowing back into your home.

If there’s insufficient warm air blowing over your evaporator coil, the evaporator coil will drop in temperature, causing the coil to freeze. When your AC isn’t running, the ice that’s developed on the coils has time to thaw, which leads to water leaking inside your home.

Once your AC turns back on, the coil will begin to freeze all over again.

Typically, a frozen evaporator coil can be caused by one (or several) of the issues below:

  • A refrigerant leak - As we mentioned, your evaporator coil uses refrigerant to absorb heat from your home’s air. If your refrigerant levels drop (due to a leak somewhere in the lines), the coils will become colder than intended and start to freeze over.
  • Blocked or closed return vents - If your return vents are blocked or closed, your AC will struggle to provide sufficient warm air to your evaporator coil, causing the coil to eventually freeze.
  • A dirty air filter - A clogged filter blocks airflow to the evaporator coil. This blockage causes the coil to freeze due to a lack of warm air blowing over it.
A clean air filter (left) vs a dirty air filter (right)

The solution: If you think a frozen evaporator coil is the problem, check your air filter and replace it if it’s noticeably dirty.

Also, make sure that all your air vents are open and free of any blockage/obstruction.

If you’ve tried these suggestions and the problem still persists, it means you likely have a refrigerant leak, which you will need a professional to handle for you.

If your AC drain pan is cracked or rusted, the water that it’s meant to collect will leak out and onto your floor.

As we mentioned earlier, the AC drain pan (made of either plastic or galvanized metal) is located directly underneath your evaporator coil inside the system. During normal operation, the drain pan collects all the condensation that drips off the evaporator coils.

Eventually, that water drains into the condensate drain line and is safely dumped outside via the condensate drain pipe.

Over time, due to age, wear and tear, or rust (if the pan is metal), your drain pan can crack, causing the collected water to leak and pool around your AC unit.

The solution: We recommend leaving this job to the professionals. A pro HVAC Technician can easily replace your old drain pan with a new one and ensure that you have the right pan for your specific unit.

We offer quick, same-day air conditioning repairs. To learn what to expect when you hire us, visit our AC repair page for more information.

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