Imagine this scenario: it's a hot summer day, and you come home to escape the heat by turning on your trusty air conditioning unit. But as you walk towards it, you notice something troubling - a small puddle of water on the floor, and drops of water coming from the unit itself. You have a leaking air conditioning unit, and you're left wondering what could be causing it.

A leaking air conditioning unit can be frustrating and stressful, but don't worry - we're here to help you understand why this might be happening and how to fix it. In this comprehensive guide, we'll explore the various reasons why your air conditioning unit might be leaking, and provide you with some practical tips and tricks to get it back in working order.

Leaking Air Conditioning Unit

Understanding Your Air Conditioning Unit

Before we dive into the reasons why your air conditioning unit is leaking, let's take a moment to understand how it works. Your air conditioning unit contains two coils - the evaporator coil and the condenser coil. The evaporator coil is responsible for cooling the air in your home, while the condenser coil releases the heat outside. The coils work together to create cool air that's circulated through your home via ductwork.

Common Air Conditioning Problems: Causes of AC Unit Leaks

Air conditioning is an essential component of modern living, providing cool air during hot summer months. However, just like any other appliance, air conditioning units can experience problems. One of the most common issues that homeowners face is a leaking air conditioning unit. Not only is this issue frustrating, but it can also be an indicator of more significant problems. There are several reasons why your air conditioning unit may be leaking, and it's important to identify the root cause to address the issue effectively. Here are some of the most common air conditioning problems that can cause leaks:

Clogged Drain Line

Your air conditioning unit has a drain line that's responsible for removing the moisture that's extracted from the air. Over time, this drain line can become clogged with dirt, dust, and other debris. When this happens, the moisture has nowhere to go and can back up, causing your air conditioning unit to leak.

Dirty Air Filter

Your air conditioning unit's air filter is responsible for removing dust and other particles from the air. If the filter becomes clogged with dirt and dust, it can cause the evaporator coil to freeze up. When this happens, the ice can melt and cause the air conditioning unit to leak.

Low Refrigerant Levels

Refrigerant is a crucial component of your air conditioning unit. It's responsible for absorbing heat from the air in your home and releasing it outside. If your air conditioning unit has low refrigerant levels, it can cause the evaporator coil to freeze up and eventually leak.

Damaged or Dirty Coils

If the evaporator or condenser coils are dirty or damaged, it can cause your air conditioning unit to leak. Dirty coils can cause the unit to work harder than it should, which can lead to leaks. Damaged coils can cause refrigerant to leak out, which can also cause leaks.

Frozen Evaporator Coils

As mentioned earlier, a dirty air filter or low refrigerant levels can cause the evaporator coil to freeze up. When this happens, the ice can melt and cause your air conditioning unit to leak. This is because the excess water created by the melting ice can overflow the drain pan and spill onto the floor.

A dirty air filter can restrict airflow to the evaporator coil, causing it to become too cold and freeze up. It's essential to replace your air filter regularly to ensure proper airflow and prevent this from happening.

Broken Condensate Pump

Your air conditioning unit has a condensate pump that's responsible for pumping the moisture that's extracted from the air outside of your home. If the pump is broken, it can cause the moisture to back up and eventually leak.

Improper Installation

If your air conditioning unit was improperly installed, it can cause leaks. For example, if the unit was not installed at level, it can cause the condensate to accumulate in the wrong area and eventually leak. Improper installation can also cause problems with the refrigerant lines, leading to leaks.

When installing an air conditioning unit, it's essential to ensure that it's installed correctly. This includes ensuring that the unit is level to prevent condensate from accumulating in the wrong area. Additionally, refrigerant lines must be installed correctly to prevent leaks.

How to Fix AC Unit Leaks

Fixing an AC unit leak can seem daunting, but with the right tools and knowledge, it's a task that can be easily tackled. Before you start fixing your AC unit leak, you need to ensure you have the necessary tools.

Some of the tools you may need include a bucket, a wrench, a screwdriver, a refrigerant recharge kit, a coil cleaner, a pipe cleaner, a wet/dry vacuum, and a soft brush or cloth. You may also need refrigerant if low levels are causing the leak. Now that you have your tools and have identified the common causes of air conditioning unit leaks, let's discuss how to fix them.

Clearing the Drain Line

The first step is to locate the drain line, which is typically a PVC pipe that runs from the indoor unit to the outside of your home. Once you've located the drain line, turn off the power to your AC unit to prevent any accidents.

Next, you'll need to remove the cap from the end of the drain line outside your home. This cap is typically located near the ground and can be easily removed by hand or a wrench. Once you've removed the cap, you should see water flowing out of the drain line. If you don't see any water, the drain line is likely clogged.

To clear the clog, you can use a wet/dry vacuum to suction out any debris or buildup from the drain line. Alternatively, you can use a pipe cleaner or a long, thin brush to gently push the clog through the drain line. Be careful not to damage the drain line or push the clog further into the line.

After you've cleared the clog, replace the cap on the end of the drain line and turn the power back on to your AC unit. Monitor your unit for any further leaks or issues.

Changing the Air Filter

Locate the air filter, which is typically located behind the return air grille or in the air handler unit. The air filter may be a disposable filter or a washable filter, depending on your unit. To change a disposable filter, simply remove the old filter and dispose of it properly. Then, replace it with a new filter of the same size and rating. Make sure the filter is installed in the correct direction, with the airflow arrow pointing towards the unit.

If you have a washable filter, remove the filter and wash it with mild soap and water. Rinse thoroughly and let it dry completely before reinstalling. It's important to clean your washable filter regularly, ideally once a month during peak usage.

In terms of tools, you may need a screwdriver to remove the return air grille or access panel to reach the air filter. You may also need a vacuum or soft brush to clean any debris or dust that has accumulated in the filter compartment.

Recharging the Refrigerant

First, you'll need to determine the type of refrigerant your AC unit uses. This information can usually be found on the unit itself or in the owner's manual. Once you've identified the refrigerant, you'll need to purchase a refrigerant recharge kit. These kits can be found at most hardware stores or online.

Before you begin the recharge process, make sure your AC unit is turned off and the power supply is disconnected. You'll also need to locate the refrigerant access port on your AC unit. This port is usually located on the outside of the unit and is covered by a cap.

Next, attach the recharge hose from the kit to the access port. The hose should snap onto the port securely. Open the valve on the recharge kit and slowly begin to add refrigerant to the system. It's important to add refrigerant slowly and in small increments to prevent overcharging the system.

As you add refrigerant, monitor the pressure gauges on the recharge kit to ensure you're adding the correct amount. Once the pressure gauge reaches the recommended level for your system, close the valve on the recharge kit and disconnect the hose from the access port.

Finally, replace the cap on the access port and turn your AC unit back on. You should now have a properly charged AC system and any leaks caused by low refrigerant levels should be fixed. It's important to note that recharging the refrigerant in your AC unit, according to EPA regulations, should only be done by a trained professional if you're not comfortable doing it yourself.

Cleaning the Coils

To clean the coils, you'll need to turn off the power to your air conditioning unit and remove the outer cover. Once the cover is removed, you can use a soft brush, cloth, and a coil cleaner to gently clean the coils. Be sure to remove any debris that's stuck to the coils. If the coils are heavily clogged, professional cleaning may be necessary to prevent further damage to the unit. Regular cleaning of the coils can help keep the AC unit running efficiently and prevent leaks from occurring.

Thawing Frozen Evaporator Coils

When the evaporator coils of an air conditioning unit freeze over, it can cause water to accumulate and eventually lead to leaks. Thawing the frozen evaporator coils is necessary to prevent this issue. To do this, the AC unit must be turned off to prevent further damage to the system. Then, the fan setting should be switched to "on" to help circulate warm air throughout the unit and aid in thawing the coils. 

It's important to avoid using any sharp objects to remove the ice, as this can damage the coils. Once the coils have thawed, it's a good idea to check for any additional issues that may have caused the freezing, such as a clogged air filter or low refrigerant levels. 

Repairing or Replacing the Condensate Pump

To replace the condensate pump, start by turning off the power to the AC unit to prevent any electrical hazards. Then, locate the pump and remove it from the unit by disconnecting the electrical wiring and drainage tubing. It's important to take note of the make and model of the old pump to ensure that the replacement pump is compatible with the unit.

Once the old pump has been removed, install the new pump by reconnecting the electrical wiring and drainage tubing in the same way that the old pump was connected. Be sure to test the new pump to ensure that it's working properly before turning the AC unit back on.

Seeking Professional Help

If you're unsure of how to fix your air conditioning unit or if you've tried to fix it and it's still leaking, it's best to seek professional help. A licensed HVAC technician can diagnose the problem and make the necessary repairs.

Preventing AC Unit Leaks

Preventing AC unit leaks can save you from the hassle and expense of frequent repairs or replacements. By taking these preventive measures, you can ensure that your AC unit runs efficiently and smoothly without any leaks. Here are some tips:

Regular Maintenance

  • Clean or replace the air filter every 1-2 months
  • Clear the drain line regularly
  • Have your unit serviced by a professional every year
  • Keep the area around your air conditioning unit free of debris

Proper Installation of your air conditioning unit is crucial to prevent leaks. One of the most important things to ensure during installation is that the unit is level. If it is installed on an uneven surface, water can accumulate in the wrong areas and cause leaks. Additionally, it is important to ensure that the drain line is properly installed and connected.

The drain line is responsible for carrying condensate away from the unit, so if it is not connected correctly or is clogged, water can build up and cause leaks. A professional HVAC technician can ensure that your AC unit is installed correctly and that the drain line is properly connected to prevent any potential leaks. By taking the time to properly install and connect your AC unit, you can avoid costly repairs and replacements in the future.


Air conditioning unit leaks can be frustrating and can cause damage to your home. By understanding the common causes of AC unit leaks and how to fix them, you can save yourself time, money, and frustration. Remember to perform regular maintenance on your unit and seek professional help if needed.

If you do encounter a leak, identifying the cause and taking appropriate action, such as repairing or replacing the condensate pump, can resolve the issue. If you require assistance with AC unit leaks or other HVAC and plumbing needs, GO Heating, Air & Plumbing is available to provide expert service and support to ensure your home stays comfortable and safe year-round. We provide services in Plano and the nearby areas. We hope to work with you soon!

air conditioning unit is leaking


How do I know if my air conditioning unit is leaking?

  • Look at the floor of your house or apartment. If it's wet, then you probably leak. If not, check out the walls around the unit and check for dampness there as well. If nothing seems unusual, turn off the unit and flip on a light switch in an area near it—if you notice moisture on the ceiling or walls in that room, then it's likely that your AC unit is leaking water into those areas.

Can I fix a clogged drain line myself?

  • Yes, you can fix a clogged drain line yourself. However, it is important to know when to call a professional. If you are not sure about your ability to fix the problem, it is best to contact an expert. A plumber can usually determine the severity of the issue and tell you if you need to hire them or if you can do it yourself.

How often should I replace my air filter?

  • You should replace your air filter every 6-12 months, or every 2 months if you have pets.

Is it safe to recharge the refrigerant in my air conditioning unit myself?

  • While you can recharge the refrigerant by yourself, according to EPA regulations, only certified professionals should do so as it can be harmful to you and the environment if mishandled.