Jul 2023

Are you noticing pools of water on the floor where your aircon is? Or are you spotting water stains or discolouration on the walls or ceiling near the aircon? If so, there is a chance that your aircon is leaking water.

A leaking aircon can be problematic – it can cause water damage to your walls, floors and furniture, and can also lead to the growth of mould and mildew, as well as the presence of unpleasant odours.

If you’re facing this issue, read on as we share some common reasons for a leaking aircon and how you can fix it and prevent a leak from occurring again. We also share the answers to your frequently asked questions (FAQs) about aircon leaks!

Reasons Why Your Aircon Is Leaking Water

To fix a leaking aircon, you’ll first need to determine the reason for the leak. Here are 11 common reasons why an aircon may be leaking water.

1. Full drain pan

Located beneath the indoor evaporator coils, the drain pan serves as a collection point for the condensation generated when the aircon cools warm air.

On days when humidity is high, a large amount of condensation may accumulate in the pan, causing it to overflow. This overflow, in turn, leads to water leakage from your aircon unit.

2. Damaged or broken drain pan

The drain pan, which is typically made of iron, is susceptible to rusting and corrosion. When either of these occurs, gaps may form in the drain pan and cause water to leak.

To determine if your drain pan is damaged or broken, inspect the edges and corners for signs of holes, cracks or notches. Any of these can result in water leaks.

3. Dirty aircon filters

When your aircon filters become dirty, the dirt obstructs the airflow, making it difficult for the air to reach the evaporator coil. As a result, the coil becomes cold and ice eventually forms. When the ice melts, a large amount of water is produced. The water levels may subsequently exceed the drain pan’s capacity, leading to leakages from your aircon unit.

Moreover, the build-up of dust on the filters can infiltrate the drain line, creating clogs that prevent proper drainage of water. This may, in turn, cause water to back up into your aircon.

4. Clogged drain line

A clogged drain line is one of the most common causes of a leaking aircon. The presence of dirt, dust, and fungus can obstruct the smooth flow of water. As a result, the water may accumulate and back up within the unit, ultimately causing the aircon to leak.

5. Improper installation of the aircon

If your newly purchased aircon starts leaking on its very first day of use, you may want to check if it has been installed correctly and evenly. An unlevel unit can cause water to leak from the drain pan instead of being pumped out via the drain line.

If an uneven installation is ruled out, we recommend consulting a professional to identify any potential installation issues.

6. Leaking refrigerant

Refrigerant is the substance responsible for converting warm air in your room into cool air and sometimes, this liquid may leak from your aircon.

If you observe leaks accompanied by a warmer-than-usual airflow, it could indicate an issue with the refrigerant. Additionally, if you notice a bubbling sound coupled with a minor leak, you’re probably experiencing a refrigerant leak.


If you suspect a refrigerant leak, turn off the aircon and contact a professional repair company immediately. Inhaling or coming into contact with the refrigerant can result in lung and skin irritation, and prolonged exposure can be detrimental to your health.

7. Malfunctioning condensate pump

The condensate pump is responsible for extracting water from the drain pan. Due to the accumulation of dirt, the pump may fail to draw water from the drain pan into the drain line. As a result, the drain pan overflows, causing water to leak from your aircon.

8. Leaking condenser coil

Typically placed outside the home, the condenser unit of your aircon consists of components such as a blower fan, compressor, and condenser coil.

As it’s found outdoors, the condenser unit is more susceptible to an accumulation of dust, dirt, and grime. This buildup of dirt and debris can potentially lead to blockages that can, in turn, result in water leaks.

9. Frozen evaporator coils

Frozen evaporator coils typically arise from one of three causes: a refrigerant leak, dirty air filters, or a dirty evaporator coil. When the ice on the frozen coils eventually melts, the drain pan will overflow, leading to water leaks.

10. Air leakage

An air leak occurs when the warm air entering the aircon fails to pass through the vent. This causes moisture to condense on the refrigerant coils, leading to water leaks.

An air leak can also occur due to loose seals. If the aircon’s ductwork isn’t properly sealed and insulated, humid air can enter the system. When this air mixes with the cooler air within the ducts, condensation will form. Over time, the water will accumulate and overflow, causing a leak.

11. Old pipes

Over time, the protective coating of your aircon pipe can deteriorate due to wear and tear, potentially resulting in water leaks.

How To Fix A Leaking Aircon

Now that you know the common reasons for an aircon leak, here’s how you can fix the problem.

Clean the aircon filters

Dirty aircon filters can result in icy evaporator coils and clogged drain lines. By cleaning the aircon filters, you may be able to address the issue and fix the leak.


Before cleaning the aircon filters, be sure to check your aircon unit’s instruction manual first. Some filters can be washed, while others must be replaced entirely.

To clean the filters, follow the steps below:

  1. Open the front cover of the aircon unit and carefully remove the filters.
  2. Wipe the front cover with a microfibre cloth.
  3. Use the tube extension of your vacuum cleaner to get rid of loose dirt or large particles on the filters.
  4. Mix some mild soap with lukewarm water in a large basin.
  5. Wash the filters in the solution.
  6. Rinse the filters with clean water to get rid of the soapy mixture.
  7. Let the filters air dry completely before placing them back into the aircon.

Contact a professional repair company

If the leak isn’t caused by dirty aircon filters, it’s best to contact a professional repair company for help.

Professional repair companies have trained technicians who possess the knowledge and experience to accurately diagnose and resolve aircon leaks. They have a deep understanding of the intricacies of aircon systems and can accurately identify the underlying causes of leaks.

Moreover, they’ll be equipped with the right tools and equipment to handle the repair work effectively and safely. Thus, you can enjoy peace of mind knowing that your aircon and house won’t be damaged.

What to do while waiting for the technician:

If your appointment with the technician is some time away, you can take the following interim steps to reduce the amount of water damage caused by the leaks:

  • Wipe away any water found on the walls to prevent damaging the paint.
  • If you have wood floors, quickly wipe away any puddles that accumulate on the surface to prevent water from seeping into the wood and causing water damage.
  • Place a dehumidifier in your room to prevent the growth of mould and mildew.

Selleys Dehumidifier is a desiccant dehumidifier that can be placed inside furniture such as wardrobes or shoe racks, or in rooms such as the kitchen or bathroom.

Featuring an advanced formulation, this dehumidifier effectively absorbs harmful formaldehydes (VOCs) present in the air. As the formaldehydes are absorbed, the white beads within the box will gradually change colour, turning brown or black. (You’ll only require 1 box to remove all traces of formaldehydes in the room!)

In addition to its formaldehyde-absorbing capabilities, Selleys Dehumidifier also works to absorb moisture and freshen the air. This is especially helpful when tackling the high humidity levels caused by a leaking aircon.

Each box of Selleys Dehumidifier has a lifespan of 2 – 3 months, depending on the humidity level of the room or space.

How To Prevent Your Aircon From Leaking

Water damage can be costly to repair. Instead of repairing your home after the leak has occurred, it’s best to prevent the leak from occurring in the first place. Read on for some tips to prevent your aircon from leaking.

Clean your aircon regularly

The presence of dirt, dust and other contaminants can cause your aircon to leak. Thus, an important step in preventing such situations from occurring is to make cleaning your aircon a routine! If your aircon filters can be washed, we recommend cleaning them once every 2 weeks to prevent the buildup of dirt and dust.

Schedule yearly aircon maintenance

Scheduling regular maintenance or checks is key to ensuring your aircon remains in its best condition. These routine checks allow you to identify any potential problems that may arise and resolve them in a timely manner.

By addressing these issues promptly, you can prevent them from evolving into more severe problems, which often require more costly repairs. Furthermore, timely repairs can even prolong the lifespan of your aircon unit.

Fix any issues as soon as possible

If you notice any issues or irregularities with your aircon, it’s best to contact a professional repair company immediately. Delaying repairs can exacerbate the issue and potentially lead to appliance damage, which could result in higher repair costs.

FAQs About A Leaking Aircon

It depends! It’s common to find a small puddle of water under the condensing unit – this typically isn’t an issue. Additionally, if a small amount of water is leaking from your aircon and the leakage is near the drain pipe, it usually isn’t a cause for concern. This often occurs when the aircon is used on extremely hot days.

However, if there’s a big leak originating from your aircon or condensing unit, it may indicate a more severe problem. In such cases, it’s best to contact a professional repair company immediately.

Yes, you may still use your aircon while it’s leaking. However, we recommend against it as you may damage the appliance and cause further complications. Instead, contact a professional repair company to fix the leak as soon as possible.