Aircon Leaking Water? 5 Common Causes Before You Call a Technician

You wake up, walk into the bedroom, and notice a puddle of water on the floor beneath your aircon unit.

Or worse a damp patch spreading across your ceiling.

A leaking aircon is one of the most common problems Malaysian homeowners face, especially in a high-humidity climate like KL and Selangor. The good news: most causes are straightforward, and some you can even troubleshoot yourself before picking up the phone.

Here are the 5 most common reasons your aircon is leaking water and what to do about each one.

Why Does an Aircon Produce Water in the First Place?

Before we get into the causes, a quick explanation: your aircon produces water as a normal part of the cooling process. The indoor unit pulls warm, humid air from your room over a cold evaporator coil. Moisture from the air condenses on the coil like water droplets forming on a cold glass and drips into a drain pan, where it flows out through a drainage pipe.

When everything is working properly, you never see this water. When something goes wrong in this process, water ends up somewhere it shouldn't on your floor, ceiling, or wall.

Cause 1: Blocked or Clogged Drainage Pipe (Most Common)

Likelihood: Very High

This is by far the most common cause of aircon water leaks in Malaysia. The condensate drainage pipe usually a small PVC pipe running from your indoor unit to a drain outside collects mould, algae, dust, and mineral deposits over time, especially in Malaysia's humid climate. When it gets blocked, water has nowhere to go and backs up into the drain pan, overflowing onto your ceiling or floor.

Signs this is your problem:

• Water dripping steadily from the bottom of the indoor unit

• Water stains on the ceiling directly below the unit

• The unit is cooling fine just leaking

Can you fix it yourself? Sometimes. If the blockage is minor, you can try:

1. Locate the drain pipe outlet (usually exits outside the building as a small PVC pipe)

2. Use a wet/dry vacuum to suck out the blockage from the pipe exit

3. Pour a small amount of diluted vinegar into the drain line opening to dissolve organic buildup

If the blockage is deep inside the wall, or water keeps coming back after clearing call a technician. Forcing compressed air into drain pipes without knowing the layout can cause damage.

Professional fix: A chemical wash service includes full drain pipe flushing as standard this is one of the main reasons regular chemical washing prevents leaks.

Cause 2: Dirty or Clogged Air Filter

Likelihood: High

Your aircon's air filter traps dust, hair, and particles from the air. When it gets too dirty, it restricts airflow over the evaporator coil. Without enough warm air flowing across it, the refrigerant inside the coil gets too cold and the coil freezes over. When the ice eventually melts, you get a sudden rush of water more than the drain pan can handle causing an overflow leak.

Signs this is your problem:

• Aircon seems less cold than usual before the leak appears

• You can visually see dust and debris caked on the filter

• The unit runs but cooling feels weak

Can you fix it yourself? Yes filter cleaning is the one DIY job every homeowner can do safely:

1. Turn off the aircon

2. Open the front panel of the indoor unit

3. Remove the filter (usually slides or clips out easily)

4. Wash it under running water, let it dry completely

5. Reinstall and turn the unit back on

Clean your filter every 2–4 weeks in Malaysian conditions dust buildup happens faster here than in countries with lower humidity and air pollution.

Prevention: Regular general cleaning service every 3–6 months ensures filters and internal components are kept clean by a professional.

Cause 3: Dirty or Frozen Evaporator Coil

Likelihood: Medium–High

Even if your filter is clean, the evaporator coil itself can get dirty over time especially if the unit hasn't been chemically washed in over a year. A layer of grime, mould, or calcium deposits on the coil acts as insulation, reducing the coil's ability to absorb heat. This causes the coil temperature to drop too low, freezing the condensation that forms on it. When the unit shuts off or defrosts, the ice melts rapidly producing more water than the drain system can handle.

You might also notice ice forming visibly on the coil or the copper pipes near the indoor unit.

Signs this is your problem:

• Unit blows warm or weak air followed by a water leak

• You can see ice on the unit or copper pipes

• A musty or mouldy smell coming from the aircon

Can you fix it yourself? Partially. You can:

• Turn off the unit and let it defrost completely (1–2 hours)

• Check and clean the air filter

• Ensure all air vents in the room are open (blocked vents restrict airflow)

But if the coil itself is dirty, only a chemical wash can properly clean it. This is not a DIY job cleaning the evaporator coil requires proper chemicals, equipment, and technique to avoid damaging the delicate fins.

Professional fix: A chemical wash or chemical overhaul cleans the evaporator coil thoroughly, removing the buildup that causes freezing and leaking.

Cause 4: Low Refrigerant (Gas) Level

Likelihood: Medium

Refrigerant commonly called "gas" in Malaysia is the chemical compound that makes your aircon cold. It's a closed system: refrigerant doesn't get used up during normal operation. If the level is low, it almost always means there's a leak somewhere in the system.

Low refrigerant causes the pressure inside the evaporator coil to drop, making the coil temperature fall below freezing even during normal operation. The coil ices up, and when it thaws, water leaks out.

Signs this is your problem:

• Aircon is leaking water AND not cooling properly

• You hear a hissing or bubbling sound from the indoor or outdoor unit

• The copper pipe near the outdoor unit is frosted or iced over

• The problem keeps coming back even after drain pipe cleaning

Can you fix it yourself? No. Refrigerant handling requires professional equipment and training. This is not a DIY repair. Attempting to top up refrigerant without finding and fixing the leak is a temporary fix at best the gas will leak out again within weeks or months.

A technician needs to:

1. Identify the source of the refrigerant leak

2. Repair or seal the leak

3. Recharge the system to the correct pressure

MY AC COOL includes a free gas top-up of 20 psi with every chemical wash and chemical overhaul service.

Cause 5: Damaged, Cracked, or Misaligned Drain Pan

Likelihood: Medium (older units)

The drain pan sits directly beneath the evaporator coil and catches all the condensation water before it drains out through the pipe. In older units (5+ years), the drain pan can develop hairline cracks from heat cycling, rust from moisture exposure, or physical damage. Even a small crack will cause a steady drip. In some cases, a unit that wasn't installed level will cause water to pool on one side of the pan and overflow before it reaches the drain outlet.

Signs this is your problem:

• Steady drip from a specific point on the indoor unit

• The unit is older (5–8+ years)

• Drain pipe is clear and not blocked, but still leaking

• Unit was recently moved or reinstalled

Can you fix it yourself? Minor pan cracks can be temporarily sealed with waterproof epoxy, but a cracked pan almost always means the unit needs a service inspection. If the unit isn't level, a technician can adjust the bracket angle so water flows correctly into the drain outlet.

Quick Diagnosis Guide

Not sure which cause applies to you? Use this:

When to Call a Technician Immediately

Don't wait if you notice any of these:

• Water is dripping onto electrical components, sockets, or wiring

• The ceiling is stained or bulging from water damage

• The unit is making hissing, gurgling, or bubbling sounds

• Ice is visible anywhere on the unit or pipes

• You've cleared the drain pipe but the leak keeps coming back within days

Left untreated, an aircon water leak can cause ceiling damage, mould growth inside walls, short circuits, and compressor failure all significantly more expensive to fix than the original leak.

How to Prevent Aircon Leaking Water

The good news: almost all of these causes are preventable with regular servicing.

A single chemical wash (from RM 150) covers causes 1, 2, and 3 simultaneously drain pipe flush, filter clean, and coil flush all in one visit.

Stop the Leak Book MY AC COOL Today

If your aircon is leaking water in Kuala Lumpur or Selangor, MY AC COOL's certified technicians can diagnose and fix the problem fast often same day.

Our water leak fix is included FREE with every chemical wash and chemical overhaul service. That's a saving of RM 130 on the leak repair alone.

What you get:

• 💦 Water leaking fix (worth RM 130) included FREE

• 🧼 Full chemical wash of indoor and outdoor unit

• 🔋 Free gas refill up to 20 psi

• 🚗 Free transportation, toll and parking

• ✅ 30-day water leaking warranty

• ❌ No hidden charges

Chemical wash starting from RM 150/unit (1.0–1.5hp wall-mounted). The more units you service, the more you save.

📱 WhatsApp us now: 018-400 6624 🌐 Book online: myaccool.com

Serving KL, Selangor & Negeri Sembilan