What is the difference between a chemical wash and a chemical overhaul?
A chemical wash keeps the aircon on the wall: the blower fan and drain pan come out for a PowerJet wash, and the coil gets chemical, then a PowerJet deep clean. A chemical overhaul dismantles the unit so the inside and back of the coil are cleaned too. An overhaul is the last resort, for an extremely soiled unit.
Key takeaways
- General servicing is the baseline: filters, blower fan, drain pan and the coil face are cleaned in place, with the unit on the wall.
- A chemical wash adds coil chemical: the coil gets chemical then a PowerJet deep clean and the fan and pan come back as new, but the back of the coil stays out of reach.
- A chemical overhaul strips the unit: every part is cleaned inside out, then the pipes are leak-checked and evacuated.
- Steam and DIY foam are not shortcuts: in Uncle Eric's experience they push dirt deeper or leave the coil choked.
In the video above, Uncle Eric explains why we do not offer steam cleaning, and what really separates a chemical wash from a chemical overhaul, which customers ask about more than anything else.
How do servicing, chemical wash and chemical overhaul compare?
| General servicing | Chemical wash | Chemical overhaul |
|---|---|---|---|
Scope | Air filter, front panel, blower fan, drain pan, drain pipe, face of the coil | Blower fan and drain pan PowerJet-washed back to as-new condition; coil chemical, then a PowerJet deep clean of the coil; no gas check | Every part cleaned inside out: coil from both sides, blower fan, drain pan, casing, back body; includes a gas check and top-up and a deep evacuation |
Dismantling | Unit stays on the wall; fan and drain pan cleaned in place | Unit stays on the wall; fan and drain pan removed | Unit taken off the wall and stripped; refrigerant pipes disconnected |
Time on site | Depends on the unit | About 10 to 15 minutes per unit | At least 45 minutes to an hour or more per unit: strip, clean, rebuild, leak check and evacuation |
When it is needed | Routine upkeep of a healthy unit | A slimy, mouldy or blocked blower fan and drain pan | An extremely soiled unit, as a last resort |
Signs | Cools well, serviced on schedule | Black slime on the blower fan, a blocked drain pan, a musty smell | Leaks or poor cooling that a wash did not fix, heavy slime, a smell that keeps returning |
Which one does my aircon need?
- It cools well and is serviced regularly: general servicing is enough.
- Cooling is weaker or dirt is packed in the coil: premium servicing, with its PowerJet deep clean of the coil.
- Coil grime that water alone does not shift, a slimy or blocked fan or drain pan, or a musty smell that will not clear: a chemical wash.
- An extremely soiled unit still leaks or is not cold after cleaning on the wall: a chemical overhaul, as the last resort.
- A clean unit still blows warm air: cleaning again will not help. The cause may be gas or a faulty part, which needs a check instead.
- Not sure: let the technician open the unit and show you what is inside. We recommend what suits each unit's condition, and the choice is always yours.
Once you know which level you need, see the full price list and book in under a minute.
What is done in general servicing?
General servicing is routine upkeep for a unit that is working properly. When our team arrives, we switch the aircon on and check cooling, airflow, how the blower fan turns, any squeaks or vibration, and the outdoor unit. Then we clean the air filter and front panel, clean the blower fan and drain pan in place, flush the drain pipe and clean the face of the coil. You can watch: what is done for normal servicing.
In our premium servicing, the evaporator coil gets a PowerJet deep clean with our high-pressure jet, and the blower fan and drain pan are taken out and washed with the same jet, with the unit left on the wall. If dirt is packed deep in the coil, this deep clean shifts it.
What does a chemical wash add?
A chemical wash adds coil chemical to a PowerJet clean: with the unit on the wall, proper chemical goes on the evaporator coil to remove dirt and grime before a PowerJet deep clean flushes it out, and the blower fan and drain pan are taken out, washed with PowerJet and go back in as-new condition. It suits a grimy coil and a fan and pan that are slimy, mouldy or blocked, which is where many musty smells and drips start. For a very dirty coil, Viper's non-toxic heavy-duty evaporator coil cleaner is an add-on from S$30, advised on site. A chemical wash takes about 10 to 15 minutes per unit and does not include a gas check.
A wash still cannot reach the whole coil. Its limit, as Uncle Eric puts it, is simple logic. Because the unit is not removed, all the cleaning is done from the front and top. If the coil is dirty underneath or inside, or the back of the coil and casing is clogged with jelly-like slime, a chemical wash cannot reach it. Repeat it as often as you like and those areas stay dirty, because the coil and the back body have not been separated. Persistent water leaks and poor cooling often start in exactly those hidden areas.
What happens in a chemical overhaul?
In a chemical overhaul, the indoor unit is dismounted and stripped. The coil is separated from the body and every part is cleaned inside out with coil chemical and PowerJet, then reassembled and mounted back on the wall.
Coil chemicals are either alkaline or acid-based. We use alkaline coil cleaners only in extreme conditions, and any chemical is diluted and then rinsed out completely, because residue left in the thin aluminium fins keeps corroding them.
Because the refrigerant pipes are disconnected, an overhaul must end with a leak check and a vacuum evacuation. That is why every chemical overhaul includes a free gas check and top-up (worth S$165) and a deep evacuation (worth S$395), and any flare joints we remake during it are under warranty. An overhaul takes at least 45 minutes to an hour or more per unit. We explain why in is a chemical overhaul safe for my aircon?
What about steam cleaning and DIY foam sprays?
Uncle Eric does not recommend either. Steam tends to push dirt further into the coil, and if the blower fan is not taken out and washed, the dirt simply stays trapped inside. That is why we do not offer it.
The DIY foam cans sold in hardware shops have the same problem. Over the years we have seen many units where the owner tried one, the coil ended up so choked that almost no air came out, and they had to call us anyway. In the end they paid twice.
What it costs
Job | Price | What drives it |
|---|---|---|
General servicing, per wall unit | S$60 for one unit | Unit type |
Chemical wash, per wall unit | S$120 per unit | Heavy-duty coil cleaner, if advised on site, is an add-on from S$30 |
Chemical overhaul, per wall unit | S$180 | BTU size, access to the unit |
Chemical overhaul, ceiling cassette | Quoted after the S$150 on-site inspection | Ceiling access, unit size |
An overhaul costs more because there is far more labour: taking the unit down, stripping it, rebuilding it and the vacuum work at the end. For how the cooling circuit itself works, see how an aircon works and where it goes wrong.
When to call a technician
- Water drips from the indoor unit, even after servicing.
- The aircon takes much longer than before to cool the room.
- A musty smell returns soon after cleaning.
- You can see black slime on the blower fan or dust packed on the coil.
- The unit has not been serviced for a year or more.
Every service comes with a 90-day warranty. Book online in under a minute with instant confirmation, or chat with Luna, our AI assistant, on WhatsApp any time.
Frequently asked questions
Can a chemical wash fix a leaking aircon?
Sometimes. If the leak comes from a slimy, clogged drain pan or a blocked drain pipe, a chemical wash with a drain flush often solves it. If the cause is something else, such as a damaged pan or dirt deep in the coil, a wash will not fix it.
Do I need a chemical overhaul every year?
No. An overhaul is a last resort, for an extremely soiled unit, because taking it apart carries a higher risk of gas leaks. Regular servicing with a PowerJet wash keeps the coil and blower fan clean enough that many units go a long time without needing one.
Is a chemical wash safe for inverter aircons?
Yes. The type of compressor does not change how the indoor unit is cleaned. The blower fan and drain pan are taken out and washed, while coil chemical loosens the dirt and grime on the coil and a PowerJet deep clean flushes it out, with the unit on the wall.
Which works out cheaper in the long run?
Regular servicing is the cheapest way to keep an aircon clean, because it stops build-up before it needs heavier cleaning. A chemical wash costs less per visit than an overhaul, and an overhaul is kept as the last resort for an extremely soiled unit.
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.
