When Is a Chemical Overhaul the Right Job?
Ever had an aircon that smells worse the longer it runs? Sometimes washing on the wall just isn’t enough.
You can usually tell by the smell. A strong sour odour every time the aircon starts, black specks blowing out of the vents, or a unit that drips no matter how often the drain is flushed all point to heavy build-up inside the fan coil unit.
In those cases the dirt is packed deep into the blower wheel, the back of the evaporator coil and the drain pan. A chemical wash can’t reach all of it with the unit assembled. An aircon chemical overhaul takes the unit apart so we can clean every surface by hand.
We see this most in older Jurong estates, and Brian’s team at Cool Earth Aircon has been opening up these units since 2007. Many resale flats in Taman Jurong, Boon Lay and Yuhua have units that have run for years with only filter washes. Some still run on R22 refrigerant, an older gas that is being phased out under the Montreal Protocol, so a unit that old deserves a proper look inside.
What Happens During a Chemical Overhaul?
Here’s how a typical visit goes. Industry guides in Singapore, such as the one from Helpling, put an overhaul at roughly 3 to 5 hours per unit, so a flat with 2 to 4 wall-mounted units can take a good part of the day.
- Check and quote. The technician looks at the unit, explains what they see and confirms the price.
- PCB isolation. Power is switched off and the PCB control board is removed or sealed off so no liquid can reach it.
- Dismantle. The front panel, filters, drain pan, swing louvres, housing and blower wheel come off.
- Clean part by part. Each part is washed with cleaning solution and rinsed. The coil is treated on the wall with a wash bag fitted.
- Wear check. The fan motor, bearings and drain pan are checked for cracks, play or noise while they are out.
- Reassemble and test. The unit goes back together, the drain is flow-tested and the unit runs until it reaches proper cooling.
You’ll see exactly what came out of your unit. Most people don’t forget the first time they see jelly sludge from a drain pan.
Signs Your Unit Needs an Overhaul
Black mould blowing out
See dark specks on the louvres or the wall below the unit? Black mould has colonised the blower wheel. It needs to come out and be scrubbed.
Strong sour smell
A mild musty smell can be washed out. A sharp sour smell that fills the room usually means heavy mould deep in the unit.
Water leaks that keep coming back
Sludge in the drain pan blocks water flow and overflows. An overhaul clears it properly instead of pushing it further down the line.
This matters beyond wet floors. NEA’s public messaging points out that Aedes mosquitoes breed in clean, stagnant water, and a choked drain line can leave exactly that behind.
Severe loss of cooling on an older unit
When a unit over five years old has never had a deep clean, an overhaul is usually the first step before any talk of gas or parts. Dirt on the coil and blower can mimic a gas problem. Clean first, then decide.
Chemical Wash vs Chemical Overhaul
| Chemical wash | Chemical overhaul | |
|---|---|---|
| Unit dismantled | No, stays on the wall | Yes, part by part |
| Best for | Weak cooling, mild smells | Heavy mould, sour smell, sludge |
| Price per unit | From S$80 | S$130 to S$180 |
| Wear check on parts | Visual only | Each part checked |
Not sure which your unit needs? Read about our chemical wash or send us a photo. We won’t sell you an overhaul if a wash will do.
After the Overhaul
Keep the result fresh by washing filters every few weeks and booking general aircon servicing in Jurong every 3 to 4 months. Our guide on how often to service your aircon explains why the interval matters in Jurong’s humid climate.
If the overhaul shows a part is wearing out, we can quote an aircon repair on the spot. Send us a photo of your unit today, and we’ll tell you honestly whether it needs an aircon chemical overhaul or just a wash.
