What Causes AC Units to Leak Water and How to Prevent It

In summer, temperatures in Charlotte, NC often reach the mid-90s. With high humidity and frequent thunderstorms, locals rely on their air conditioners for relief. Unfortunately, these same conditions place cooling systems under tremendous stress. Pooling water around air handlers is a common sign of this stress. Here are five causes of AC leaks plus tips for preventing them.

1. Frozen Evaporator Coils

AC leaks typically occur at or just beneath the air handlers. Your air conditioner’s indoor air handler houses its evaporator coil. During each cooling cycle, your AC blows warm air over this component. Icy refrigerant within the evaporator coil extracts the air’s humidity and heat before traveling to the outdoor condenser unit as a hot gas.

Over time, evaporator coils can develop tacky buildups of dust and other grime. These accumulations inhibit heat transfer, so cold refrigerant remains cold, and evaporator coils eventually ice over. When these frosty coatings melt, they’ll leave small puddles on your floor.

The best way to prevent your AC’s evaporator coil from freezing is to have a professional clean it at least once a year. Coil cleaning is a standard part of professional AC maintenance. Scheduling a preseason AC tune-up will help you sidestep this problem and comply with the terms of your AC manufacturer’s warranty.

2. Blocked Condensate Drains

By regulating your indoor humidity, your AC keeps the interior of your home from feeling muggy and oppressive. If your indoor air feels heavy or clammy while your AC is on, and you notice a large pool of water by your air handler, there’s a good chance that you have a clog in the condensate drain line.

Air conditioners shed collected humidity as condensation. Once condensed, this moisture travels out of the building via the condensate drain line. When air conditioners lie dormant during autumn and winter, condensate drains often develop slimy buildups of biofilms, algae, and other microorganisms.

If your indoor air smells musty or moldy whenever the AC is running, or it circulates damp, warm air rather than cool, dry air, you might have a blocked condensate drain. To avoid this problem, be sure to schedule AC service each year before the summer season arrives.

3. Dirty Air Filters

Dirty HVAC air filters are among the most common causes of air conditioner leaks. All the air entering your air conditioner passes through its air filter. If this air travels through a heavy, lint-like buildup on your filter’s mesh, your AC must work harder to move it. This extra effort can lead to icing or overheating, a frozen evaporator coil, and standing water near your air handler.

To avoid filter-related leaks, inspect your air filter once a month. Simply take it out, and hold it up to the light. If light can pass through built-up filter debris, air can also move through it. The best replacement schedule for standard HVAC air filters is once every 30 to 90 days.

4. Leaky Refrigerant Lines

When AC leaks accompany hissing or screeching sounds from the outdoor condenser unit, they’re often the result of damaged refrigerant lines. AC refrigerant is the lifeblood of your cooling system. Your air conditioner transfers heat and humidity by pumping refrigerant to and from the air handler.

Your air conditioner’s compressor pumps refrigerant throughout your cooling system by pressurizing and depressurizing it. Screeching, hissing, and squealing sounds indicate that your compressor is struggling to do its job.

During annual AC maintenance, our technicians measure refrigerant levels and run compressor tests. This allows our team to catch and correct refrigerant line leaks before they cause premature compressor failure.

5. General Airflow Obstructions

Dirty air filters aren’t the only thing that can compromise airflow throughout your cooling system. Closed HVAC air vents, dirty air ducts, and blocked condenser units can also cause frozen evaporator coils and leaks. Ensure your outdoor condenser unit always has at least 2 feet of clearance by removing overgrown weeds, grass, shrubs, and other debris. Don’t close air vents throughout your home to direct unwanted air to another area, and keep your HVAC air ducts clean. According to the National Air Duct Cleaners Association (NADCA), you can maintain optimum air duct performance by scheduling professional duct cleaning every three to five years.

For more than 30 years, we’ve helped Charlotte homeowners maintain reliable, high-functioning cooling systems. We offer expert AC maintenance and repair, as well as replacement services. If you need help diagnosing, fixing, or preventing air conditioner leaks, give Integrity Heating & Cooling a call today!