Why Is My Window Air Conditioner Leaking Water?

Some water leaking from a window air conditioner is typically a normal occurrence. But significant moisture escaping from the cooling unit can be worrisome.

So why does a window air conditioner leak water? We researched the possible sources of this issue and here's what we found.

A window air conditioner can leak because of different reasons, which may include (but aren’t limited to) the following:

  • Dirty filters
  • Low Freon
  • Condensation drain clog
  • Damaged condensate pan
  • Faulty condensate pump

Take note that the steps needed to repair the leak typically depend on the source of the issue. Continue reading as we discuss these underlying concerns that can lead to window air conditioners leaking water. We'll also talk about possible solutions to these issues later in this post.

A window air conditioning unit on the window, Why Is My Window Air Conditioner Leaking Water?

Do Window Air Conditioners Leak Water?

A certain degree of condensation is generally a normal occurrence for many air conditioning systems, including window models. But an underlying concern might exist if water escaping the appliance seems excessive.

An air conditioning unit on the window

What Causes A Window Air Conditioner To Leak Water?

Water leakage on the floor

Some possible causes of water leaks from window air conditioners are:

Dirty Filters

Dirty air filters in window air conditioners can lead to moisture getting confined within the system. The result is a formation of ice crystals that can melt when the AC is off, leading to significant water leaks.

Energy.gov recommends cleaning your air conditioner’s filter at least once every two weeks. The frequency to clean and maintain an AC unit, particularly window units, may increase depending on the property’s location and living conditions.

For example, pet hair and dander may get into the filter, causing blockage over time. Homes in fairly dusty neighborhoods may also experience their window cooling units becoming dirty sooner than later. If these scenarios exist, it might be prudent for homeowners to clean their window air conditioner filters at least once a week.

Low Freon

Freon is a widely used coolant or refrigerant used in many window air conditioners. If an AC unit runs low on this substance, the AC’s pressure to convert heat will also reduce. In turn, the appliance creates more moisture than intended, causing it to leak.

Oftentimes, the solution to low Freon levels is to recharge the cooling unit. However, a leak in the coolant’s reservoir can cause the substance to escape the appliance, leading to additional problems.

You’ll know if your window AC unit has a Freon leak if it has:

  • An unknown hissing sound
  • Frozen condenser or evaporator coils
  • Low or no cold airflow

A sudden surge in your property’s energy bill may also indicate a refrigerant leak in your window air conditioner. It’s because the cooling system would generally use extra power for it to run as normally as possible.

Condensation Drain Clog

A window air conditioning unit at the second story of a house

Water vapor generated inside the window air conditioner will have nowhere to go if the condensation drain has a blockage. Also called the condensate drain, this component works as an exit route for collected moisture. It functions by applying the following steps:

  1. The evaporator coil removes excess humidity from the air nearby.
  2. The coil condenses the air and transforms it into water vapor.
  3. The condensate drain pan should collect the excess moisture before the water enters the drain line.
  4. The water travels through the drain pipe to be discharged through the outside section of the window AC.

If the condensation drain has a clog, water can pool in the system aside from it leaking out. If left unchecked, the excess moisture can invite additional issues, which may also lead to the permanent breakdown of the AC.

Additionally, read our post about a window air conditioner’s drain plug to know if you should remove it.

Damaged Condensate Pan

An unprotected window air conditioner can be susceptible to weather damage, causing components like the condensate pan to receive damages.

In particular, cold outside temperatures can interfere with the warm environment in the AC. This mixture of hot and cold temperatures can create cracks on the condensate pan.

Don’t forget to check out our post on window air conditioners in the winter to know if you need to take out this appliance during this season.

Faulty Condensate Pump

A condensate pump in a window AC unit can fail, leading to the collected moisture staying within the reservoir. In turn, the pump fails to push the water out of the system, leading to leaks.

Take note that this component works by using the following steps:

  1. The condensate pump collects the water from the air conditioning system.
  2. A float rises in the container as the water level increases.
  3. The float hits a switch when it reaches a certain point.
  4. This switch triggers the pump to push and remove the excess moisture from the unit.

Check if the condensate pump is receiving power from the mains by using a multi-meter. If it does, you can tap its micro-switch on the main float gently.

Then, inspect the areas in and around the pump to check for signs of wear and tear to verify if this component is the source of the AC’s water leak.

How Do I Stop My Window Air Conditioner From Leaking?

A window air conditioning unit for a small room

It's best to use appropriate methods to fix window air conditioner leaks instead of haphazardly tinkering with these appliances. In this section, you’ll learn some possible fixes to window AC water leaks based on offending parts:

Clean Filters

Before proceeding with any troubleshooting, repair, or replacement operation for your window AC system, make sure to turn off and/or disconnect the appliance from its power source. Doing so will help prevent potential hazards, such as electrocution or short circuits.

Additionally, consult your owner’s manual or ask the window AC’s manufacturer if you need to apply some unique steps.

Keep in mind that some air conditioning models may have distinct features that may demand dissimilar procedures to fix them properly, especially when trying to open the front hatch to access the filter for cleaning.

After taking note of those details, here are some relatively common steps to clean a window AC unit’s dirty filters to help eliminate and prevent leaks:

What You’ll Need

  • Soft brush
  • Mild cleaner (optional)

Step-by-Step Guide

  1. Lift or take out the window AC’s front grille to expose the filters.
  2. Remove the dirty filters from the unit.
  3. Rinse the filters under warm or room temperature water while scrubbing away loose dirt with a soft brush.
  4. Scrub the filters with a mild cleaning solution to help remove stubborn filth.
  5. Place the filter outside and under a shaded area to air dry.
  6. Reinstall the dried filters into the air conditioner and close or return the front grille.

Check out this mild cleaner on Amazon.

Recharge A Window Air Conditioner

Make sure that you possess the confidence and a sufficient amount of knowledge before going through with this undertaking. Recharging a window air conditioner with Freon or coolant may lead to increased risks of damage if done improperly.

Contact a certified technician to help you with this job if you feel that you’re not up to it.

If you wish to proceed with this operation, here are the steps to do it:

What You’ll Need

  • Freon canister
  • Pressure gauge set
  • 3 x 4-foot long hoses
  • Compatible valves

Step-by-Step Guide

  1. Disconnect the window air conditioner from its power source.
  2. Open the unit and take it out from its window casing. Set the air conditioner aside on a clean and flat surface.
  3. Attach the Freon to the pressure gauge set using the valves and hoses. Then, connect the pressure gauge to the air conditioner.
  4. Twist the Freon canister’s valve to increase the pressure up to a certain level. Once it reaches the recommended level, close the gauge to reduce the pressure.
  5. Repeat the 4th step as many times as necessary until the window AC unit has its coolant reserves recharged.
  6. Reinstall the cooling unit back to its window casing.

Take note that the amount of Freon and pressure needed to recharge window ACs is dissimilar between each model. Consult your owner’s guide to know these precise values before attempting to refill the appliance’s refrigerant levels.

Watch the clip below to gain additional insight on how to recharge your window AC system:

Final Words

A window air conditioning unit on the window

A window air conditioner can leak water because of different reasons. These causes may include dirty filters, low coolant reserves, or faulty condensation pumps.

Make sure to troubleshoot the unit first to find out the exact cause of the problem to apply the correct solution.

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