AC Water Dripping Inside Room: How to Unblock the Drain Line
By Anoop Nair (Refrigeration Tech)
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Published on July 05, 2026
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5 min read
Water dripping from your indoor split AC is a common household issue. If water is running down your wallpaper, the system's drainage pathway is blocked or restricted.
Why Indoor Units Condense Water When your AC runs, the indoor evaporator coil gets very cold. As warm, humid room air passes over it, moisture condenses on the cold metal fins (similar to water droplets forming on a cold glass). This water drips into a plastic drain pan directly below the coil and flows out of the room through a drainage pipe.
Common Causes of Water Dripping 1. **Algae or Mold Blockage:** The combination of dust and moisture inside the drain pan creates a gelatinous slime (mold/algae) that blocks the drain pipe outlet. 2. **Incorrect Tilt:** If the indoor unit chassis is not mounted with a slight tilt towards the drain pipe outlet, water will pool and overflow the pan. 3. **Blocked Filters:** Clogged filters restrict airflow, causing the evaporator coils to freeze. When the ice melts, it overflows the drain pan. 4. **Cracked Drain Pan:** Heat and aging can crack the plastic drain tray.
How to Unblock the Drain Line * **Step 1: Check the Filters:** Remove and wash the air filters. If they are clean, proceed to step 2. * **Step 2: Locate the Drain Pipe Outlet:** Find where the drain pipe terminates outside your home. * **Step 3: Flush the Drain Pipe:** If the pipe is accessible, use a high-pressure water pump or a wet-dry vacuum to clear the blockage. * **Step 4: Chemical Slime Flush:** Pour a diluted solution of household white vinegar or a specialized HVAC coil cleaner down the indoor drain pan to dissolve organic blockages.
If water continues to drip, contact CoolWing AC Services. Our technicians will inspect the pan alignment and clear the drainage lines using high-pressure jet wash pumps.