Why Does My Air Handler Keep Filling Up With Water?

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When there is water buildup in your air handler drip pan, the first place to look is to a clogged condensate line. However, the simplest answer may not always be the only answer. There are several components to the air conditioning system that may be contributing to your condensate line clog. It also helps to have a basic understanding of the air conditioning system and how it works.


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If your air handler drain pan keeps filling up with water, there may be a clog in the condensate line.

Cooling Your Air

The refrigerant inside your air conditioning system is designed to remove heat from your house and transfer it outside. This movement of heat allows your house to cool. The air handler is inside the house and contains the evaporator and a blower fan that circulates the air. Usually there is a filter close by. The refrigerant takes the heat that it collects at the evaporator and pumps it outside to the condensing unit, where the refrigerant releases its heat before it is pumped back into the house.


Dripping Caused by Condensation

Moisture is left on the evaporator when the warm air inside contacts the cool evaporator. When enough moisture is present, it drips into a pan. The evaporator works along the same principle of water accumulating (condensing) on the outside of a cold glass. As a coaster would collect the water from your glass, the drip pan collects the water from the evaporator, and it flows out the condensate line that usually leads outside the house.


Clogged Condensate Line

There are several reasons why the condensate line clogs and then the drip pan will fill with water. One is that the evaporator is loaded with debris like hair, dirt, or dust. The evaporator will then not operate properly, and the humidity level will be higher in your home and in the air handler. Algae may grow in the drip pan and the condensate line, causing it to clog. Another reason for a clogged condensate line is that dirt, dust, and hair can clog it directly. In the wintertime when air conditioning units aren't typically used, the slime or algae can grow then, or pests can clog the condensate line from the outside.


Regular Preventive Maintenance

Regular preventive maintenance solves a lot of problems. An air filter can be replaced once a month, but in a household with pets or smoking or during a dry season, it may be necessary to change the filter more often. This helps to keep the evaporator clean.


Occasionally pouring a little bleach down the port of the condensate line will kill any algae. A professional air conditioning company will remove all the dirt from the evaporator and the condenser outside to allow the system to function properly. This will allow the system to work longer and can help to reduce maintenance costs.


Unclogging the Line

If you've got a clogged condensate line, there are several things that can be done to unclog the line. The best way is to try to remove the clog using a wet/dry shop-type vacuum. This will usually pull the clog through from the outside end. If your condensate line is removable, you may have to take it outside and force water through it with a water hose. It is not recommended that you pour drain cleaners down the line. If you cannot remove the clog, call an HVAC professional.