Condensate Clogging Problems: Causes and Signs

man fixing an air conditioner
The air conditioner’s (AC) condensate drain line drains water out of the unit. Drainage problems, such as those that occur due to clogging, can cause multiple problems for the AC. Below are some reasons and signs for condensate drain problems.


Various things can clog the condensate line. Here are some common culprits.

Dusty Surroundings
The air filter should trap and keep dirt from the AC, but some debris does end up in the system. The dirt can mix with condensation that forms as the air handler cools the air. If that happens, then the debris will end up in the condensate line along with the condensation. Over time, the dirt might accumulate and obstruct further condensation flow.

Mold and Algae
Mold and algae thrive in humid environments. Your Ac’s drainage system, which includes the condensate line and pan, is constantly wet. The conditions encourage mold and algae growth. The organisms can also block the condensate line if you don’t clear them in time.

P-Trap Issues
A typical AC has a P-trap that keeps air from moving in and out of the air handler outside the designated channels. The p-trap should always have water since it’s the water that prevents airflow.
Unfiltered air can easily blow into the AC if the p-trap dries. The increased air pressure can also push unusually high volumes of water into the condensate drain. Both issues can lead to condensate drain problems.

Poor Line Installation
Lastly, poor installation of the AC’s condensation system can also lead to drainage problems. Such problems rarely arise with professional service. However, A DIY installation gone wrong, say of the p-trap, or condensate line, can hinder drainage. An example is if the condensate line doesn’t have the right pitch and cannot drain under the force of gravity.


A physical examination can help you detect clogging in your AC’s drain channel. However, there are also telltale signs that should make you suspect clogging even before examining the condensate drain line. Below are some of these signs.

Flooding Signs
Drainage issues can lead to spilled water in two main ways. First, blockage or damage to the drain lines can cause condensation to spill over on the floor instead of draining into the pan. Secondly, drainage problems can also send too much water into the pan, spilling some of it.

Thus, you should suspect drainage problems if you can see signs of flooding around the evaporator coil. You should also suspect drainage problems if you can see signs of water damage, including peeling paint or floor stains.

Moldy Smell
A moldy smell points to the presence of mold somewhere in your house. As previously mentioned, mold thrives in moist places. Thus, a moldy smell might mean that your AC has spilled condensation, clogging issues, or has been having standing water for some time.

Constant AC Shutdowns
Various things can cause impaired cooling, including condensate line problems. Condensate line clogging can trigger the water safety switch, which shuts down the AC. In such a case, your AC will shut might shut down every time you switch it on.

Infrequent Flushing
Lastly, you should also suspect drainage problems if you haven’t cleaned the AC in a while. All drain liens collect debris whenever the AC is in use. You need to flush the drain lines regularly to prevent the dangerous accumulation of debris.

AC malfunctions can leave your house uncomfortable and increase your house’s electrical consumption, among other problems. Service your AC regularly to preempt such problems. Contact Steele Bros Heating, Inc., if your AC does break down. You can rely on our skills and decades of experience to have your system running efficiently again.

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