Rogelio Alvarez

By: Rogelio Alvarez on February 15th, 2024

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Why Is My AC Leaking Water: Top 5 Reasons


You are walking through your living room when you accidentally step on a puddle of water and almost fall as you struggle to avoid slipping. After mopping and wiping the floor dry, you realize the water came from a leaking air conditioner. A leaking AC poses many problems besides slips and falls, so why is it leaking in the first place?

Millions of homeowners across Los Angeles rely on their central cooling system to help keep their houses cool during the hot southern California summers. At Monkey Wrench Plumbing, Heating & Air, we’ve seen and repaired all sorts of AC issues, including a lack of cool air and water leaks. 

With over 15 years of experience, we’ve seen many problems with AC leaks. Here are the top five reasons why an AC is leaking.

  • Dirty air filter
  • Clogged drain line or cracked drain pan
  • Low refrigerant
  • Frozen evaporator coil
  • Badly sealed ducts 

In this article, we’ll explain how each one of these scenarios can be problematic for your AC and cause it to leak. By understanding these issues, you can feel assured about speaking with a technician who can help further diagnose your AC leak. 


5 Reasons Why AC is Leaking Water

There could be a number of reasons why an AC unit is leaking water. Even if a homeowner doesn’t see a visible leak, they may smell a musty, damp odor coming from within the walls or ceiling of a home. 

Although we cover the top five most common reasons why an AC leaks water, it’s highly recommended to contact a professional HVAC technician to come and inspect an issue. The HVAC technician is certified and has the proper tools and resources to diagnose a possible AC water leak. 

During the inspection, the technician can run into the following issues, starting with a dirty air filter. 


Dirty Air Filter

Dirty air filters can allow dirt and debris to build up on AC components, lowering their efficiency in draining condensation and leading to a water leak. This scenario is more likely to happen in homes with AC systems that haven’t had their air filters replaced for years. Air filters are designed to capture any dust that passes through an AC to protect crucial parts from being negatively affected by accumulated dirt.

Air conditioning system manufacturers recommend replacing the air filters every three to six months to help maintain the AC’s cooling efficiency. Duct cleaning can also help prevent dust and debris from building inside an AC unit.

Often, a leak may be located near an air conditioner’s drainage system. 


Clogged Drain Line or Cracked Drain Pan

An AC may leak water if its drain pain is damaged or the drain line is clogged. During a cooling cycle, central air conditioning systems produce moisture collected by a drainage pan and released outside through a drain line. If something blocks the flow of wastewater from exiting, it can overflow and leak. 

Some air conditioners have a second drainage pan underneath the first one to capture overflow. If either of these are cracked or damaged, water may leak through. The connecting area between a drainage pan and the drain line can get clogged up with dirt and debris, causing an overflow, which can lead to a leak. 

If the leak comes from the drain line or pan, these parts can be replaced or cleaned from any gunk clogged inside. Other components inside an AC could also be causing it to leak water.


Low Refrigerant 

Low levels of refrigerant can indirectly cause an air conditioner to leak water. Refrigerant is highly essential during the cooling process because it helps absorb heat and, under normal conditions, shouldn’t deplete. There may be a small crack or hole along the AC unit leaking refrigerant. 

If there’s a decrease in the amount of refrigerant, it may cause the evaporator to freeze. As the ice begins to melt, it can cause the drainage plan to overflow. The overflow of water can start to leak.

An HVAC technician must detect where the refrigerant leaks to prevent further AC water leaks. Once the leak is fixed and the refrigerant levels are back to normal, the water leak may cease to continue. 

Even after sealing refrigerant leaks, an evaporator coil may freeze due to other issues and cause an AC to leak water once the ice melts.


Frozen Evaporator Coil

Excess ice formed on an evaporator coil can melt and cause a water leak inside a central air conditioning system. Restricted airflow, refrigerant leaks, or other issues within an AC can cause the coil to freeze. Frozen evaporator coils can affect the cooling efficiency of an air conditioner and lead to a lack of cool air circulation

It’s also possible that the coil is faulty and unable to work correctly, causing it to freeze. The evaporator coil is another critical element of a central air conditioning system, so it’s highly recommended to have it inspected and repaired or replaced by a technician. An annual HVAC tune-up can help protect the AC unit from future leaks.

Most leaks are usually near the evaporator coil, but air conditioning system leaks can appear anywhere throughout the system, such as poorly sealed ducts.


Bad Sealed Ducts

Inadequately sealed or insulated ducts can create an environment where warm air exhausted from an AC can’t escape, producing condensation within the ductwork. As the moisture builds up, it can overflow on the drainage pan, leak out through some cracks, or accumulate in the ductwork, where it can become warped or harbor bacterial growth like mold. 

One of the leading causes of badly sealed ducts is improper air conditioner system installation. The issue should be addressed by a professional HVAC technician only.  


Addressing Air Conditioner Water Leaks

A sudden body of water or a damp odor from air ducts are major signs of an air conditioner leak. Now that you know what may be causing your AC to leak, you can better communicate with a technician about the problems behind the air conditioner leak. Regardless of what caused the leak, homeowners should address the source immediately to return to enjoying cool air from an AC. 

At Monkey Wrench Plumbing, Heating & Air, we work with the top air conditioning system manufacturers to learn how to address AC water leaks. Our technicians have successfully repaired leaking air conditioners in hundreds of homes across Los Angeles and the surrounding areas. 

If your central cooling system is experiencing water leaks, contact us using one of the buttons below. You can also schedule an appointment with an HVAC technician directly through our HVAC online scheduler

Leaks can be troublesome but fixable. Still, some homeowners may consider replacing their AC entirely to avoid further system issues. Understanding the factors that affect installation costs can help homeowners prepare a budget for a new air conditioner.