Why Is My Air Conditioner Dripping Water Inside?
An air conditioner dripping water inside your home is one of the most common problems homeowners face. It can cause ceiling stains, water damage to walls and floors, and mould growth if left unaddressed. Understanding why it happens and how to fix it can save you a costly repair bill.
How Air Conditioners Produce Condensation
As your split system air conditioner cools the air, moisture from the warm air condenses on the cold evaporator coil — the same way a cold drink sweats on a humid day. This condensation is collected in a drain pan and flows out through a drain line to the outside. When something disrupts this drainage system, water backs up and drips inside your home.
Common Causes of Indoor Water Dripping
1. Clogged Condensate Drain Line
This is the most common cause. Over time, algae, mould, dust and debris build up inside the drain line, blocking the flow of water. The drain pan overflows and water drips inside. Fix: Turn off the unit. Locate the drain line (usually a PVC pipe exiting near the outdoor unit). Use a wet/dry vacuum to suck out the clog from the outdoor end, or pour a cup of distilled white vinegar into the drain pan to clear biological growth. Repeat every 3 months as preventive maintenance.
2. Frozen Evaporator Coil
If your air conditioner runs with restricted airflow (clogged filter, closed vents) or at very low temperatures, the evaporator coil can freeze. When the ice melts, it produces more water than the drain pan can handle. Signs: Ice visible on the indoor unit or refrigerant lines, reduced cooling, unit cycling on and off. Fix: Turn off cooling mode and run fan-only to defrost. Replace the air filter. Ensure all supply and return vents are open. If freezing recurs, call a technician — it may indicate a refrigerant issue.
3. Dirty or Clogged Air Filter
A clogged filter restricts airflow over the evaporator coil, causing it to get too cold and freeze. This leads to overflow as described above. Fix: Clean or replace the filter immediately. For split systems, most filters simply unclip and can be rinsed under a tap and air-dried. Do this monthly during heavy-use periods.
4. Disconnected or Damaged Drain Pan
The drain pan under the evaporator coil can crack, rust through, or become disconnected over time. Fix: This requires a technician to replace or reseal the drain pan. Inspect the pan when cleaning the filter — look for cracks, rust stains or pooling water.
5. Improper Installation
If the indoor unit is not level, condensate may not drain toward the drain line and will pool and overflow. Fix: A technician can re-level the unit. Ensure the indoor unit slopes very slightly toward the drain outlet.
6. Low Refrigerant
Low refrigerant causes the evaporator coil to run at a lower temperature than designed, leading to freezing. This requires a licensed technician to diagnose and recharge. Do not attempt to handle refrigerant yourself.
Preventive Maintenance Checklist
- Clean the air filter every 4–6 weeks during summer and winter peak use
- Pour 100mL of white vinegar into the drain pan every 3 months
- Check the drain line outlet at the outdoor unit is not blocked or submerged
- Have the unit serviced by a technician every 1–2 years
- Ensure supply vents throughout the home are open and unobstructed
When to Call a Technician
If cleaning the filter and drain line doesn't fix the dripping, or if you see ice forming on the unit, call a licensed HVAC technician. Refrigerant leaks, damaged drain pans and electrical issues should only be handled by qualified professionals.
Upgrading Your Air Conditioner
If your air conditioner is frequently causing problems, it may be time to upgrade. Oceania Appliances stocks Daikin, Mitsubishi Electric and Fujitsu split systems with modern drain management and inverter technology. Visit our Wetherill Park showroom or contact us at support@oceaniaappliances.com.au.