Aircon Water Leaking Common Causes and How It’s Fixed

Aircon water leaking is one of the most common problems homeowners in Kuala Lumpur and Selangor call us about. Water dripping from an air conditioner looks alarming, but the good news is that most causes are straightforward to diagnose and fix. This guide walks through why your aircon is leaking water, which causes are simple versus more involved, how much a repair typically costs, and what to check before calling for a repair.

Is Some Water Normal?

A small amount of condensation is normal — your aircon naturally produces water vapour as it cools and dehumidifies the air, and this is meant to drain away through a dedicated pipe. The problem isn’t condensation itself; it’s when that water isn’t draining properly and ends up dripping into your room instead.

Common Causes of Aircon Water Leaking

1. Blocked Drain Line

This is by far the most common cause. Over time, dust, algae, and debris build up inside the condensate drain pipe, eventually blocking it. With nowhere to go, the water backs up and overflows into the indoor unit and drips out.

Fix: Clearing the blockage, often with a vacuum or pressurised flush of the drain line. This is a routine part of a proper aircon cleaning service.

2. Dirty Air Filter

A clogged filter restricts airflow over the evaporator coil, which can cause it to get too cold and freeze. When the ice eventually thaws (often when the unit is turned off), it melts faster than the drain can handle, causing dripping.

Fix: Regular filter cleaning, ideally every 2–4 weeks for units in daily use.

3. Low Refrigerant Causing Ice Build-Up

Similar to a dirty filter, low refrigerant can cause the coil to freeze. When it thaws, the resulting water often exceeds what the drain pan and line are designed to handle in one go.

Fix: This requires a refrigerant leak check and refill, not just a drainage clean — see our guide on the signs your aircon needs a gas refill for more detail.

4. Cracked or Damaged Drain Pan

The drain pan collects condensation before it flows out through the drain line. Over years of use, especially in older units, this pan can crack or corrode, allowing water to leak directly rather than draining properly.

Fix: This typically requires replacing the drain pan, which is a repair job rather than a cleaning fix.

5. Incorrect Installation Angle

If a unit wasn’t installed with the correct slight tilt toward the drain outlet, water can pool inside instead of flowing out properly. This is more common with DIY or poorly executed installations.

Fix: Reinstalling or adjusting the unit’s mounting angle — this is why professional installation matters even for something as simple-sounding as a wall-mounted unit. See our aircon installation service for properly executed setups.

6. High Humidity Beyond Normal Drainage Capacity

In particularly humid conditions, some older or undersized units may struggle to keep up with the volume of condensation produced, especially if combined with any of the issues above.

Quick Checklist Before You Call for Repair

• Has the filter been cleaned in the last month?
• Is there visible ice on the indoor unit or pipes?
• Is the leak constant, or only when the unit first turns on (which can indicate thawing ice)?
• Has the unit been serviced in the last 6–12 months?

Having these answers ready helps a technician diagnose the issue faster when you contact us.

How Much Does It Cost to Fix a Leaking Aircon?

It depends on the cause: a straightforward drain line clean is at the inexpensive end, while a cracked drain pan replacement or a refrigerant leak repair costs more. Our aircon servicing price guide lists typical repair ranges — water leaking repairs generally fall around RM 100–250 — so you know what to expect before any work begins.

Why You Shouldn’t Ignore a Leaking Aircon

Beyond the immediate mess, ignored leaks can cause:

• Water damage to ceilings, walls, or flooring beneath the unit
• Mould growth in the affected area, which is both a property and health concern
• Electrical risk if water comes into contact with wiring near the unit

Even a “minor” drip is worth addressing promptly rather than placing a bucket underneath and hoping it resolves itself. Following a regular aircon maintenance schedule is the best way to stop most leaks before they start.

Frequently Asked Questions

Why is my aircon leaking only when I turn it off?
This often points to ice that built up while running (from a dirty filter or low refrigerant) thawing once the compressor stops, releasing more water than the drain line can immediately handle.

Can I clear a blocked drain line myself?
Basic access is sometimes possible, but effectively clearing a blocked line usually requires specific tools and knowledge of the unit’s drainage layout to avoid pushing the blockage further in or damaging components.

Is a leaking aircon always a sign of a serious problem?
Not necessarily — a blocked drain line is a simple, inexpensive fix in most cases. However, ignoring it can lead to bigger issues over time, so it’s worth addressing even when the cause seems minor.

How much does it typically cost to fix an aircon water leak?
This depends on the cause — a drain line clean is generally inexpensive, while a cracked drain pan replacement or refrigerant leak repair costs more. See our price list for typical ranges.

Will cleaning my aircon prevent future leaks?
Regular cleaning significantly reduces the risk of drain blockages, which is the most common cause of leaking. It won’t prevent every possible cause (like a cracked pan), but it addresses the most frequent one. Our aircon cleaning guide shows what a proper clean includes.

Get Your Leaking Aircon Fixed Properly

Don’t just place a bucket under the drip — let us find the actual cause and fix it. Message us on WhatsApp for a diagnosis, call +60 10-593 0730, or check our water leaking repair service for more details. For a complete overview of looking after your unit, read our homeowner’s guide to aircond service in KL & Selangor.