Which aircon service do you need: general servicing, chemical wash or overhaul?
General servicing is routine upkeep, a chemical wash cleans the coil in place for weak cooling or smells, and an overhaul takes the unit apart for neglect.
By the HomeMaster team · · Updated · 5 min read
Book general servicing when your aircon is cooling normally and is simply due. Book a chemical wash when cooling has dropped off or a musty smell has survived a normal service. Book a chemical overhaul when a unit has gone years without proper care, leaks from a tray clogged with buildup, or starts smelling again soon after a wash.
It is easy to get this wrong in one of two ways: paying for an overhaul when a wash would do, or paying for general servicing three times before anyone says the unit needed a wash. This guide matches what you notice to the service that fixes it.
Symptom to service: a quick guide
Start with what the unit is doing, not with the name of the service.
| What you notice | What to book | Why |
|---|---|---|
| Cooling normally, just due | General servicing | Routine upkeep keeps it that way |
| Weaker cooling, even with clean filters | Chemical wash | Dirt on the coil is restricting airflow |
| Musty smell that a normal service did not fix | Chemical wash | Growth on the damp coil, which a filter clean cannot reach |
| Smell back within a month or two of a wash | Chemical overhaul | The unit is holding water somewhere, often the tray |
| Water dripping indoors, for the first time | General servicing | The drain may simply need clearing |
| Water dripping again and again | Chemical overhaul | A clogged tray needs the fan coil taken apart |
| Neglected for years | Chemical overhaul | Buildup is past what an in-place clean can shift |
| Needs gas every few months | A leak check, not another top-up | Refrigerant runs in a closed loop, so it only runs low through a leak |
| Will not start, keeps tripping the circuit breaker, grinding noise | A repair, not a service | Cleaning cannot fix a failed part |
If you are unsure which row you are in, check the filters first. A clogged filter can cause weak cooling and dripping on its own, and rinsing it takes minutes.
General servicing: routine upkeep
General servicing is maintenance for a unit that works properly. The technician cleans the filters and the accessible surfaces, checks and clears the drainage, vacuums out dust, and runs a function test at the end.
HDB's home-care advice makes the case for it: regular maintenance helps prolong an aircon's lifespan and keep it running efficiently.
It takes roughly 20 minutes a unit, so four units are normally done inside 90 minutes. For a unit in daily use, every 3 to 4 months is the rhythm that keeps the coil and drain from clogging in the first place; our guide on how often to service your aircon goes into the schedule.
What it is not: a deep chemical clean or a repair. If cooling has dropped, or a smell or leak has already set in, a general service may not be enough on its own. See our general servicing page for the details.
Chemical wash: a deeper clean of the coil, in place
A chemical wash cleans the cooling coil and its surrounding parts with chemical cleaner while the unit stays on the wall. It reaches the dirt and growth on the coil that a filter clean leaves behind.
Book one when cooling has gradually weakened, when a musty smell comes back after routine servicing, or when the coil is visibly caked. That smell is biological growth on a coil that stays damp almost all the time in Singapore, and a chemical wash is what removes it.
It takes roughly 30 minutes a unit. It does not fix low refrigerant, a failed compressor or an electrical fault. More on our chemical wash page.
Chemical overhaul: taken apart and cleaned fully
A chemical overhaul is the deepest of the three. The fan coil is dismantled, every part is cleaned, and the unit is put back together. Taking it apart gives access to places an in-place wash cannot reach, including the drain tray and the parts around it.
It suits a unit neglected for years, a unit that keeps leaking because the tray is clogged, or a smell that returns soon after a wash. Allow about an hour a unit. An overhaul costs more and takes longer, so it is worth checking the cause first rather than booking the most thorough option by default. More on our chemical overhaul page.
Time and price for each
| General servicing | Chemical wash | Chemical overhaul | |
|---|---|---|---|
| What happens | Filters, surfaces, drainage, function test | Coil cleaned in place with chemicals | Fan coil dismantled, cleaned, reassembled |
| Rough time per unit | About 20 minutes | About 30 minutes | About an hour |
| One unit with HomeMaster | From $50 | From $80 | From $150 |
Prices for more units are on each service page. Every price includes GST, weekends and public holidays cost the same as a weekday, and there is nothing extra for paying by card or PayNow.
Gas top-ups and repairs: what cleaning cannot fix
Gas top-ups
A gas top-up refills refrigerant, and it is only the right answer for a unit that is genuinely low. Refrigerant circulates in a sealed loop and is not used up as the unit runs. So a unit that needs gas again a few months after the last top-up has a leak, and topping it up once more is money spent on the symptom.
The honest sequence is to find and repair the leak, then refill. Neither a chemical wash nor an overhaul repairs a refrigerant leak, because cleaning does not touch the sealed circuit. Gas top-ups are priced by the type of gas, R22 or R410a, and window and portable units are quoted separately.
Repairs
Some faults are repairs, not cleaning jobs: a compressor or capacitor that has failed, an electrical fault, a refrigerant leak, or an installation problem such as a unit that was never level. If that is what a unit has, a technician should say so rather than sell you a wash that cannot help.
HomeMaster services residential aircon units: general servicing, chemical wash, chemical overhaul, gas top-ups, and dismantling and reinstallation, plus quarterly and tri-yearly servicing plans. We do not install new units or do electrical or ducting work.
Choosing and booking with HomeMaster
If you are not sure which service fits, tell Helen, our AI assistant on WhatsApp, what the unit is doing and how many units you have. She will point you to the service that matches the symptom, then show real open slots and the exact total for your unit count. You can also book directly on our aircon servicing page.
Before the visit you get a reminder, you can ask Helen at any time who is coming, and afterwards a receipt arrives on WhatsApp. Someone needs to let the technician in and be there at the end to confirm the work.
Frequently asked questions
Is a chemical wash better than general servicing?
Not better, just different. General servicing is routine upkeep for a unit that cools normally. A chemical wash is a deeper clean of the coil for a unit whose cooling has weakened or that smells musty after a normal service. Booking a wash for a healthy unit is money you did not need to spend.
How often do I need a chemical wash?
Only when a symptom calls for it, such as weak cooling or a lingering smell. Regular general servicing every 3 to 4 months is what keeps a unit from reaching that point. If a unit keeps needing washes close together, something is holding water and an overhaul may be the real fix.
Will a chemical overhaul stop my aircon leaking water?
If the leak comes from a drain tray clogged with buildup, an overhaul is usually what fixes it, because the tray can only be cleaned properly with the fan coil taken apart. It will not fix a leak caused by poor installation or a refrigerant leak, which need an installer or a repair.
Do I need to be home for aircon servicing?
Someone needs to let the technician in and be there at the end, because you will be asked to confirm the work. Helen arranges access with you before the visit.
Sources
- Maintaining Air Conditioners in HDB Flats, Housing & Development Board
Aircon due for a service?
See real open times and the exact total for your units before you book. GST included, and weekends cost the same as weekdays.
