Why is water leaking from my AC?
Learn why your AC unit is leaking water with our guide. Understanding the cause of the problem is crucial. Read on to find out how an evaporator coil and warm air create condensation.
“Why is water leaking from my AC? "
..There are multiple causes of this problem.
So, Before we get into the causes of a leaking AC unit; In order to better understand why this is happening, you must first understand exactly how and why the water is forming on your AC in the first place.
Why does water form in my air conditioner?
An air conditioner has two main pieces that work together to provide the cooling we all enjoy in our comfortable homes. The indoor section of the AC unit is called an evaporator coil.
The moisture on this coil is called 'condensation' produced by the mixture of the cold pressurized pipes within the evaporator coil and the warm/hot air from your home that passes through the evaporator coil during the A/C's operation.

Once the water trickles down the evaporator coil, it depends on the drain pan within the coil box to catch the water and begin its journey through the condensate drain line. (a white PVC pipe) that leads out of your home. The evaporator coil is usually attached to a gas furnace that’s located inside the home or garage. The gas furnace is the heating unit, but it also contains the blower which is used for both the heating & cooling, as it distributes the conditioned air throughout your home...
When the A/C is operating, all three of the units we’ve discussed up to this point, are in operation. Refrigerant is pumped through the evaporator coils by the condenser; which is the unit outside we typically label as the air conditioner
That’s an easy question to answer, but not an easy task to resolve for good. The condensation line is the drain for the water that’s dripping from that indoor coil, meaning, that the water is collecting the debris from the coil.
Again you’ll need to ask yourself, “why is my coil so dirty?”
The short answer to that question is, your filters aren't being changed enough, or there are leaks in the air system, allowing the dirt to get into the airflow. This is not just draining into your home, but that means your air quality is not good.
Cause 1: A plugged up condensate drain line
So, with all that in mind, here are a few things that cause a water spillage or leak in your home:
A clogged condensate drain line is one of the most common causes that water may be leaking from your AC into your home. If the drain line gets plugged up with dust, dirt, or sludge, that water backs up into your home. In that case, you’ll need to unclog it. Unclogging the pipe is an easy task when attempting to resolve this issue.
If there is dust, dirt, or sludge in the drainpipe; you must ask yourself, "why?, How did it get in there?”
This is a huge problem that you must resolve before additional property damage occurs, or the backpressure being backed up into the furnace may begin to damage the internal parts of both the gas furnace and the condenser unit.
The only way to resolve such an important issue is to perform a full restoration of the equipment, by cleaning it all out, piece by piece. The coil should be removed and thoroughly cleaned out, as well as the blower motor and wheel.
In an old air conditioner around 12-15 years old, The drain pan may be damaged or rusted through, allowing it to fall right through. You'll need to replace the pan.
If there is dust, dirt, or sludge in the drainpipe; you must ask yourself, “why?, How did it get in there?”
Cause 2: Damaged/rusted drain pan
A dirty air filter limits the amount of airflow passing over the evaporator coil. When this happens, the evaporator coil gets too cold and freezes. Often, this may even cause the coil to freeze into a solid ice cube, and once it melts, an excess amount of water will have problems draining because the primary condensate pan may not handle the extra water load.

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Cause 3: A dirty air filter or Evaporator coil
That’s an easy question to answer, but not an easy task to resolve for good. The condensation line is the drain for the water that’s dripping from that indoor coil, meaning, that the water is collecting the debris from the coil…
Again you’ll need to ask yourself, “why is my coil so dirty?”
The short answer to that question is, your filters aren't being changed enough, or there are leaks in the air system, allowing the dirt to get into the airflow. This is not just draining into your home, but that means your air quality is not good.
Cause 4: Low refrigerant
If you have a low refrigerant charge, the lower pressure of the refrigerant will cause a lower temperature of that refrigerant you do have, causing the lines to ice up on the AC system. This will cause the evaporator coil to freeze. When the ice begins to melt, water overflows the drain pan.
You'll notice you're low on refrigerant when:
- The air conditioner can't cool your home efficiently.
- The copper lines connecting your indoor and outdoor AC equipment will turn white with ice covering the pipes and the compressor.
- If you see oil saturation on or around the piping, it will typically indicate a leak from the copper fittings. That's a sign that the installing company didn't braze the pipes correctly, and they neglected to perform a leak test on the lines they installed.
You may find that a professional is the easiest way to go forward if you’re experiencing water leakage from the indoor AC unit. Call us @ Silicon Valley Comfort for quick 24-hour service and a precise diagnosis of the issue(s) that you are experiencing.\

This article’s emphasis on the need to understand why water is forming on the AC before addressing the causes of leaks is a helpful approach for troubleshooting the issue. By noting that there are multiple potential causes of AC leaks, this article acknowledges that this is a complex problem that may require professional expertise to fully resolve.
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