Why is My AC Leaking Water?

Arlington, TX – When you experience an AC leak it can be a pretty concerning situation. When you call us,  Metro Express Service technicians will identify the problem, and take care of it for you. If your air conditioner has not been serviced this season, it’s a good idea to call for an AC tuneup. A tune-up can prevent a leaking AC, while ensuring its best performance, protecting your home’s structure and your health.

How Water Forms in AC

An air conditioner absorbs the warm air and moisture from the inside of your home. As the moisture is removed and the air-cooled, condensation forms on the air conditioner’s coils. From the coil, it drops into a drip pan. The water drains out of your home through a drain line from the drip pan. Scheduling routine maintenance helps maintain the proper operation of your air conditioner, including cleaning the pan and condensate drain line when necessary.

In the following, the 6 most common causes of an AC leak are discussed.

The 6 Most Common Causes of an AC Leak

  • A clogged condensate drain is a common cause of an overflowing pan. If not periodically cleaned, the drain can clog due to mold, dust, mildew, or sludge. Routine maintenance will prevent a clogged drain from occurring.
  • A broken condensate pump can cause the drain pan to overflow. The condensate pump isn’t present on all air conditioners. Many air conditioners drain by simple gravity. An example of where the pump would be needed is when the unit is located in a basement. If the pump malfunctions, water can’t be pumped out and the drain pan can overflow.
  • A damaged drain pan can leak due to cracks, rust, or other damage.
  • A refrigerant leak causes the evaporator coil to freeze up. It appears as ice or “frost” on the coil, and you may hear a hissing sound. When the evaporator coil thaws, water in the pan can overflow. Refrigerant leaks should be repaired quickly, and the unit shut off. Some units can be permanently damaged if the safety shutoff doesn’t kick in to shut down your air conditioner.
  • A dirty air filter will block airflow. This can also cause the coils to freeze up, and dripping of water will occur as they thaw. This is a simple problem to prevent if you change your filter as recommended. Generally, a filter with a higher MERV rating requires replacement less often. Check the filter each month, and more often during dusty conditions such as during the spring pollen or when remodeling your home. Homes with smokers will also require more frequent changes.
  • A blocked drain on the exterior isn’t common but may occur in some situations. Check the exterior drain site and clear away soil, overgrowing grass, or other debris.

Signs Your Condensate Drain May Need Cleaning

The condensate pan is located in a dark and humid area with limited airflow. These conditions create a perfect environment for mold, fungus, bacteria, and algae to grow. This can lead to a clogged, overflowing condensate drain and can pose a risk to your health. Maintenance is not only essential to prevent the overflow that damages your home but to prevent air-borne illnesses. EPA-approved products are necessary to control these pathogens. EPA approval indicates the testing and their approval of these products to control Legionnaires Disease. Aspergillus is another dangerous disease that can grow in drain pans.

Preventing air-born illnesses begins with a clean drain pan. While a homeowner can clean the pan, there are risks associated with handling bacteria-laden residue, and from liquids making contact with electricity or damaging components. The power to the AC unit should always be shut off in the home’s breaker box. In addition, an effective product can be caustic posing further risks due to contact or inhalation. Overall, the safest practice is to have your HVAC technician provide professional cleaning with annual HVAC maintenance. Tablets or strips are designed to reduce pathogens and drain clogging slime. The use of these products can promote a clean drain pan and a condensate drain. The treatment is provided based on the tonnage of your air conditioner.

The regular use of treatment will control the following:

  • Musty odors
  • Prevent a fall and injury related to water leaking onto floors
  • Control of air-born disease or other bacteria in the drain pan

How Dirty Coils Affect Performance and can cause an AC Leak

If the coil is dirty, the condensate dripping off of the evaporator coil onto the drain pan is also dirty. The condensation collects in the pan and drain line, contributing to a drain clog and pan overflow. To prevent an ac leak, protect your home and health by ensuring your air conditioning system receives annual maintenance. Metro Express Service technicians inspect every part of your AC to ensure it runs smoothly and is providing its best performance with an AC tuneup.


Randy Murphy

Randy Murphy has been building his knowledge of the air conditioning and heating business for several years now. He first started applying his knowledge while working for his father’s HVAC company. Later, in 1987, Randy started his own business: Metro Express Service. He has been a top 10 Trane & Amana dealer for over eight years. When it comes to heating and cooling, Randy knows the business better than anyone.
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