AC Leaking Water Inside House? 5 Causes and Quick Fixes

Waking up to water dripping from your AC onto the floor—or worse, onto your furniture or electronics—is a homeowner’s nightmare. But don’t panic. Water leaks are common and usually fixable. Here’s what’s causing it and what you can do.

Why ACs Produce Water

First, understand that your AC creating water is normal. When warm, humid air passes over the cold evaporator coil, moisture condenses—just like water droplets forming on a cold glass.

This condensate water should:

1. Collect in the drain pan
2. Flow through the drain pipe
3. Exit outside or into the drainage system

A leak means something in this process has gone wrong.

Cause #1: The “Jelly” Clog (Most Common)

The problem: In Malaysia’s high-humidity climate, dust mixes with condensation to create a thick, gel-like biofilm often called “bacterial jelly.” This slime accumulates in the drain pipe and blocks water flow, forcing it to back up and overflow from the tray.

Signs:

• Water dripping from the front of the unit
• Musty, sock-like smell from AC
• Visible slime or “algae” in the drain pan

Quick fix (DIY):

1. Turn off the AC at the main switch.
2. Find the drain pipe exit (usually outside or at a floor drain).
3. Use a wet/dry vacuum to suck the slime out from the end of the drain pipe.
4. Pour a cup of white vinegar into the drain pan (if accessible) to kill bacteria.
5. Wait 30 minutes, then flush with warm water to clear the residue.

When it needs professional help: If the blockage is deep within the unit or the “jelly” has hardened, a standard vacuum won’t reach it. We find that a chemical wash is often required to fully dissolve this biofilm and prevent it from growing back immediately.

Cause #2: Dirty Air Filter

The problem: A clogged filter restricts airflow over the evaporator coil. This causes the coil to get too cold and freeze over. When that ice eventually melts, it overwhelms the drain pan with more water than it can drain at once.

Signs:

• Ice visible on the evaporator coil
• Reduced cooling performance (air feels weak)
• Filter hasn’t been cleaned in 2-4 weeks

Quick fix (DIY):

1. Turn off the AC completely to prevent damage.
2. Remove the filters and wash them with mild soap and water.
3. Let the ice melt naturally (this may take 2-4 hours).
4. Place thick towels on the floor to catch the melting ice water.
5. Turn the AC back on only after the filter is dry and the ice is gone.

Prevention: In dusty areas like Kepong or KL city center, you should clean filters every 2 weeks.

Cause #3: Low Refrigerant (Gas)

The problem: When refrigerant levels drop, the evaporator coil pressure changes, causing it to freeze up. Just like with a dirty filter, the melting ice eventually causes a massive leak.

Signs:

• Ice forming on the copper pipes or coil
• AC is blowing warm air
• Hissing sound coming from the indoor unit
• Higher than usual electricity bills

Can you DIY? No. Refrigerant acts as a closed system and does not “expire.” If it is low, you have a leak that requires certified handling.

Professional solution: A technician must test the pressure (PSI), locate the leak, repair the copper pipe, and then top up with the correct gas (R32 or R410A).

Cause #4: Damaged or Rusted Drain Pan

The problem: The drain pan catches condensate, but older metal pans often rust through due to constant exposure to moisture. Even newer plastic pans can crack over time or become brittle.

Signs:

• Water dripping from the back or bottom corners of the unit
• Visible rust stains on the wall or unit casing
• Leak continues even after the drain line is confirmed clear

Can you DIY? You can apply a waterproof sealant to small cracks as a temporary emergency measure. However, this is rarely a permanent fix.

Professional solution: We recommend replacing the drain pan entirely, which usually involves dismantling the indoor unit.

Cause #5: Installation Issues

The problem: Wall-mounted units rely on gravity to drain water. If the unit was installed without a slight slope toward the drain pipe, water will pool in the tray until it spills over the front edge.

Signs:

• Problem started immediately after installation or a new renovation
• Water sits in the drain pan but doesn’t flow out
• The unit looks visually crooked on the wall

Can you DIY? If you have a spirit level tool (or a phone app), you can check the angle.

• Place the level on top of the unit.
• Verify it tilts slightly toward the drainage outlet side.

Professional solution: Re-installation is often necessary to adjust the mounting plate and ensure proper drainage flow.

Emergency Steps When You Discover a Leak

Immediate Actions:

1. Turn off the AC - Stop the cooling process to halt condensation.
2. Place towels/buckets - Protect your parquet or vinyl flooring immediately.
3. Move valuables - Shift electronics, remotes, and furniture away from the splash zone.
4. Document damage - Take clear photos of the leak and any water damage for insurance claims.

What NOT to Do:

• Don’t tape up the leaking area (water will just find another exit).
• Don’t ignore small drips; they often signal a larger blockage building up.
• Don’t try to drill new holes in the unit casing to drain water.

How Much Will Repair Cost?

We have compiled the average market rates for Kuala Lumpur and Selangor for 2025/2026.

Prevention is Better Than Cure

Monthly:

• Wash air filters (critical in urban areas).
• Check the outdoor pipe to ensure water drips steadily when the AC is running.

Every 6 Months:

• Schedule a chemical wash. This is the only way to remove the “jelly” buildup from the internal tray.
• Inspect gas pressure.

Annually:

• Full system overhaul if the unit is older than 5 years.
• Flush drain lines with anti-bacterial solution.

When to Call for Help Immediately

Call a professional right away if:

• Water is leaking near power points or switches.
• You smell burning plastic or ozone.
• The unit vibrates heavily while leaking.
• The ceiling shows signs of water stains or sagging.
• You have already cleaned the filters and the leak persists.

Get Your Leak Fixed Today

Water leak ruining your day? WhatsApp us at 012-2252 623 and describe the problem. We’ll give you an initial assessment over the phone.

Our chemical wash service (RM180/unit) often solves water leak issues because it:

• Clears clogged drain lines
• Cleans the drain pan
• Removes mold and algae
• Includes FREE gas top-up

Same-day service available in Kepong, Mont Kiara, Desa ParkCity, and surrounding areas. Don’t let a small leak become water damage.