Why is my Mitsubishi aircon leaking water and not cooling?
An aircon leaking water and not cooling at the same time usually has one cause: dirt. A clogged blower fan and coil block airflow, so the room stays warm, while grime fills the drain pan until water overflows. A PowerJet wash of the coil, blower fan and drain pan fixes both; if not, check the drain pipe or gas.
Key takeaways
- One cause, two symptoms: dirt blocks the airflow and the water's path out.
- The blower fan is the giveaway: black, furry blades mean it is long overdue.
- Fixed on the wall: the fans come out for washing; the coil is jet-cleaned in place.
- If it returns quickly: look at the drain pipe, the drain pan or low gas.
In the video above, three Mitsubishi wall units in one home were leaking water and not cooling. When we took the blower fans out, they were black with grime. We washed the fans and louvres in the bathroom, jet-cleaned each coil on the wall with a wash bag fitted, and put everything back. All three cooled again and stopped leaking.
How to tell what is causing it
- Look at the blower fan. Shine a torch through the air outlet. Dark, furry blades mean dirt is the cause, and a wash is the fix.
- Check where the water comes from. Water from the bottom edge of the unit usually means an overflowing drain pan. Water from the side or along the pipe points to the drain pipe or pipe insulation.
- Look for ice. Frost on the coil or the copper pipe means the coil is too cold. Dirt can cause it, but so can low gas.
- Think about timing. If it started right after a service or an installation, the drain pipe gradient or a loose drain connection is more likely than dirt.
- Count the units. If every unit failed on the same day, a shared cause such as the outdoor unit or gas is more likely.
If step 1 is where you land, book premium servicing. Dripping right now? Message Luna on WhatsApp.
How dirt causes both problems
What the dirt does | What you notice |
|---|---|
Coats the blower fan blades | Less air comes out; the room takes longer to cool |
Packs the coil fins | Less heat is taken from the air; cooling drops |
Starves the coil of airflow | The coil gets too cold and can ice up, then melts and drips |
Fills the drain pan with sludge | Water cannot drain away and overflows from the unit |
Grows mould in the damp | Musty smell when the aircon starts |
In Singapore's humidity, the coil pulls a lot of water out of the air every hour. When the drain pan's outlet is choked, it does not take long to overflow.
What the PowerJet wash covers
Our premium servicing takes the blower fan and drain pan out and PowerJet-washes them, gives the evaporator coil a PowerJet deep clean on the wall, flushes the drain and tests each unit. When the coil is coated with grease and grime, a chemical wash adds proper coil chemical before the PowerJet. For other leak causes, read 7 causes of an aircon leaking water; for Starmex units that need more than a wash, read our Mitsubishi Starmex chemical overhaul case.
What it costs
Job | Price | What drives it |
|---|---|---|
Premium servicing, 1 unit | S$80 | Number of units; multi-unit rates apply |
Chemical wash | S$120 per unit | For a coil coated in grease and grime |
Servicing carries a 90-day warranty: if the unit leaks water or stops cooling within 90 days, we come back free, unless the cause is a gas leak the unit already had.
When to call a technician
Book a check if water drips from the indoor unit, the blower fan looks black, the room no longer gets cold, or the unit smells musty. Switch it off if water is near any electrical point. Book online in under a minute, or message Luna, our AI assistant, on WhatsApp at any hour.
Frequently asked questions
Is it safe to keep using an aircon that is leaking water?
Switch it off if water is dripping near sockets, electrical points or onto furniture. A small drip from a dirty unit is not dangerous in itself, but it damages walls and floors and usually gets worse until the unit is cleaned.
Can I clear the leak myself?
Washing the air filters can help a little. The real blockage is usually in the drain pan and on the blower fan and coil, which need the unit opened and jet-washed, so it is a job for a technician.
Why did all three units go bad at the same time?
They were installed together and used in the same way for years, so dirt built up at a similar rate. If all units failed on the same day, though, a shared cause such as the outdoor unit or gas is more likely.
Will it leak again after the wash?
Not if dirt was the cause and the units are serviced regularly. If it leaks again soon after, the drain pipe gradient, a cracked drain pan or low gas freezing the coil may be to blame, and those need a check.
Is the work covered by warranty?
Yes. Servicing carries a 90-day warranty covering water leaking and not cooling, excluding problems caused by an existing gas leak.
Eric Lim, aka Uncle EricFounder of iAircon.Repair, now in its 10th year servicing aircons in Singapore. Some of our jobs are filmed, and you can watch the work on YouTube.
