Why is my aircon still leaking after a service?
When an aircon keeps leaking after a service, the cause was usually never cleared. Three things are commonly left behind: jelly-like slime inside the drain pipe, a badly clogged back coil the servicer could not reach, and pipe insulation worn thin. Each needs a different fix, so finding which one comes first.
Key takeaways
- The leak was never fixed: a quick spray-and-wipe service cleans what you can see, not the drain pipe or the back of the coil.
- Leftover slime is a head start: a drain that is only partly cleared can block again within weeks, not months.
- The back coil hides the dirt: the rear section of the coil sits against the wall and stays coated when the unit is cleaned on the wall.
- Worn insulation is not a cleaning job: if the drips come from the pipes, no servicing will stop them.
In the video above, a Mitsubishi Electric aircon was still leaking weeks after a normal servicing by another company. The unit was severely clogged and the quick clean had not reached the dirt. We did a chemical overhaul, cleaned it back to as-new, and the leak stopped.
How do you tell which one it is?
Where the water appears, and when the leak started, narrow it down.
- Look at where the water comes from. Drips from the bottom of the indoor unit point to the drain. Water spitting out with the air points to the coil. Drips from the pipes, trunking or ceiling point to the insulation.
- Think about when it started. A leak that began right after the service usually means something was knocked out of place: read why an aircon leaks after servicing. A leak that was there before and never stopped means the cause was missed.
- Shine a torch into the air outlet. Dark, furry dirt on the blower fan means the coil behind it is likely coated too.
- Check the drain outlet. If the water trickles out slowly or not at all while the aircon runs, the drain pipe is still blocked.
- Feel the pipes. Wet, cold pipes with torn or squashed insulation drip whether or not the unit is clean.
If steps 3 or 4 match, the fix is a proper clean of the coil and drain: see our aircon water leaking repair service. Dripping right now? Message Luna on WhatsApp.
What does a quick service miss?
What was missed | Why it leaks | What fixes it |
|---|---|---|
Slime left in the drain pipe | The jelly narrows the pipe until water backs up into the drain pan and overflows | Drain pipe cleared and flushed, drain pan cleaned |
A clogged back coil | Dirt in the fin gaps holds water and sends slime into the drain | A chemical overhaul, with the unit taken down |
Worn pipe insulation | Cold pipes sweat in humid air, and light condensation turns into a steady drip | Insulation replaced, quoted before any work |
Slime in the drain pipe
The water your aircon removes from the air flows out through the drain pipe. Microbes grow in that water and, over months, thicken into a jelly that sticks to the pipe. A service that only rinses the drain pan pushes some of it along but leaves the rest. Read how aircon drain pipe slime forms.
A clogged back coil
Many wall units have a coil that wraps around the blower fan. The front is easy to spray; the back section sits against the wall and cannot be reached with the unit mounted. When it is coated, it holds water and feeds slime into the drain. Read why a dirty back coil causes leaks.
Worn pipe insulation
The refrigerant pipes and drain pipe are wrapped in insulation. Over the years it tears, flattens or splits in the sun. Bare, cold pipe in Singapore's humid air drips, and a light film of condensation becomes a leak. Left too long, the water damages ceilings and walls, and the repair costs far more than the insulation.
Why does the leak seem fixed, then come back?
Our humidity means an aircon removes a lot of water every night. A drain pipe that is only partly cleared copes on a dry day and overflows on a humid one, so a leak can seem fixed for a week and then return. Drain pipes that run through trunking or a false ceiling also hide the problem until a stain appears.
What it costs
Job | Price | What drives it |
|---|---|---|
Premium servicing with PowerJet | S$80 for 1 unit | Drain pan, blower fan and coil cleaned, drain pipe cleared and flushed |
Chemical overhaul, wall-mounted | S$180 per unit | For a clogged back coil; includes a free gas check and top-up |
Pipe insulation replacement | Quoted before any work starts | Length of pipe, exposed or concealed |
When to call a technician
Call us if the leak continues after a service, if water comes from the pipes or ceiling, or if it leaks and cools poorly at the same time. For every other cause of a leak, see why an aircon leaks water. Book online in under a minute, or ask Luna, our AI assistant, on WhatsApp at any hour.
Frequently asked questions
Should the company that serviced it come back for free?
Check their warranty first. If a unit we serviced leaks within 90 days, the site inspection and fixing the leak are free; WhatsApp us photos or a video. Other companies set their own terms.
Is it the same problem as a leak that starts after a servicing?
No. A leak that starts right after a servicing usually means something was knocked out of place. A leak that was there before and never stopped means the cause was never cleared.
Will a chemical wash fix it?
Only if the dirt is on the front of the coil. A wash is done with the unit on the wall, so a clogged back coil needs a chemical overhaul. If the cause is worn insulation, no cleaning will stop the leak.
How long can I keep running a leaking aircon?
Not long. Water reaches power points, floors and false ceilings, and a slow drip soaks in before you notice it. Switch it off and use another room until the cause is fixed.
Eric Lim, aka Uncle EricFounder of iAircon.Repair, now in its 10th year servicing aircons in Singapore. Every job is filmed, so you can watch the work on YouTube.
