Why Is My Indoor Air Conditioner Dripping Water? Causes and Fixes
When your indoor air conditioning unit starts dripping water down your wall or onto your parquet floor, it causes immediate panic. In summer, an AC unit condenses between 1 and 3 liters of moisture per hour from indoor air. If this condensation cannot drain freely, it overflows the internal tray.
1. Blocked Condensate Drain Tube (Slime and Algae)
The most common cause by far: stagnant moisture in the gravity drain line fosters bacterial algae, dust sludge, and fungal biofilm, forming a gelatinous plug in the plastic hose.
Fix: Locate the exterior end of the condensate drain tube (on your balcony, facade, or bottle trap) and use a wet-dry vacuum or gentle syringe suction to clear the algae plug. Flush 100 ml of white vinegar down the indoor drain tray to kill remaining bacteria.
2. Dirty or Slanted Condensate Drain Pan
If the indoor unit was installed without a slight slope toward the drain outlet, water pools on one side and spills over the edge. Alternatively, years of dust accumulation can obstruct the narrow channel feeding the drain pipe.
3. Frozen Evaporator Coil (Low Gas or Blocked Filters)
If air filters are severely clogged or refrigerant gas is low, the evaporator coil temperature drops below 0°C, encasing the aluminum fins in solid ice. When the AC switches off, this thick ice block melts rapidly, overwhelming the drain pan and flooding the room.
4. Defective Condensate Removal Pump
In installations where gravity drainage was impossible, a miniature electric condensate pump is fitted. If the pump float switch sticks or the motor fails, the reservoir overflows instantly.
FAQ
Can I continue running the AC while it is dripping water?
No. Turn it off immediately to prevent water from reaching internal electronic circuit boards, fan motors, or warping wooden floors.
How can I prevent my AC drain from clogging each summer?
At the start of every cooling season, clean the filters and pour half a cup of white vinegar or specialized enzymatic drain cleaner into the internal drip tray.