Seeing water leak from your air conditioning unit can be frustrating, but it is a common issue with several possible causes. Air conditioners naturally create moisture as part of the cooling process. When everything works as it should, that moisture drains away safely.
When something goes wrong, water can overflow, drip from the indoor unit or pool around the system. Understanding why this happens helps you prevent damage and keep your system running efficiently.
How Air Conditioning Normally Manages Moisture
When warm indoor air passes over the cold evaporator coil, moisture condenses and forms water droplets. These droplets fall into a drain pan and should flow out through a condensate drain line. In a correctly operating system this process is clean and controlled. A leak simply means the moisture has nowhere to go or has exceeded the system’s drainage capacity.
Common Reasons an Air Conditioner Leaks Water
Blocked condensate drain line
Dirt, dust, mould or algae can build up inside the drain line and stop water from draining. When the pipe is blocked, the drain pan fills and the water begins to overflow.
Dirty or clogged air filter
If the filter is full of dust, airflow drops. Reduced airflow can cause the evaporator coil to become too cold and freeze. Once the ice melts, the excess water can overwhelm the drain pan and leak out.
Damaged or worn drain pan
Over time, drain pans can rust, crack or become misaligned. If the pan is no longer able to hold water properly, leaks will occur even if the rest of the system is working correctly.
Low refrigerant or frozen coils
Low refrigerant levels change the pressure inside the system and can cause the evaporator coil to freeze. When the ice melts, it produces more water than the system can handle, which often results in leaks.
Faulty condensate pump
Some systems rely on a pump to move water out of the building. If the pump stops working, water backs up and spills from the drain pan or indoor unit.
Incorrect installation or uneven unit placement
If the indoor unit or drain pan is not level, water cannot flow where it should. Incorrectly installed pipes or poor positioning also contribute to leaks.
What You Can Do When Your Air Conditioner Leaks
- Switch the system off to stop further overflow.
- Check and replace the air filter if it is dirty.
- Look for signs of blockage in the drain line if it is accessible.
- Inspect the drain pan for rust, cracks or overflow.
- Ensure the outdoor and indoor units are clear of debris and have proper airflow.
- Call a qualified technician if the coil has frozen, refrigerant levels are low or the cause is not obvious.
Professional air con servicing is the safest way to diagnose and repair leaks, especially if the issue involves internal components or refrigerant.
When Moisture Is Normal
A small amount of condensation is expected, especially in humid weather. As long as the water flows through the drain line and does not appear indoors, the system is working correctly. Persistent dripping, water damage or visible pooling always indicates a problem that needs attention.
Water leaking from an air conditioner is usually the result of drainage issues, dirty filters, frozen coils or simple wear and tear. Most causes are fixable and many can be prevented with regular maintenance. Keeping filters clean, ensuring good airflow and booking routine servicing will help your system stay efficient and leak free.