What to check first
Before booking, check the unit's rated tick label if you still have it, note how long it has been since the last chemical wash (not general service), and check whether your refrigerant is R32 — that is printed on the outdoor unit's nameplate.
Run the unit and note whether the smell is at start-up only or continuous, and whether water is dripping from the indoor unit onto the wall or floor below. Both details help a technician quote the right job over the phone rather than guessing on-site.
The likely causes, in order
A dirt-caked coil (most common). A dirt-caked coil is the most common reason cooling drops off, and the same buildup that traps dust also traps moisture, which is why a dirty coil often produces a musty smell on start-up as well as weaker cooling. Even a unit that met NEA's current energy performance standard when installed loses efficiency as the coil clogs. MEPS for single-split air-conditioners was raised to 4-tick on 1 Apr 2025, precisely because efficient units still need to be kept clean to perform as rated. A higher tick rating on the box does not mean the unit stays efficient without cleaning. A general wipe-down of the filter does not reach this buildup; only a full chemical soak does.
Servicing skipped for too long (second). Skipping servicing for too long is the second cause of a bigger job later. Daikin's warranty terms state that the air-conditioner has been properly installed, used and maintained is a condition of warranty coverage, and that warranty becomes void on failure to follow Daikin's instruction as regard the application, installation, use, service or maintenance. General servicing itself is excluded from the warranty, but neglecting it is not cost-free.
When to call, and who
Call an aircon servicing provider when cooling has dropped noticeably, there is a persistent musty smell, or water is leaking from the indoor unit — these are the three signs a chemical wash, not a general service, is due.
If your aircon uses R32 refrigerant, the technician needs to be trained for it, not just experienced. NEA states that to comply with SCDF's requirements on the handling of R32 air-conditioning systems in Singapore, manufacturers are required to ensure that service personnel have completed training courses conducted by ITE — ask before booking whether the technician holds that certificate.
What it costs
A chemical wash is priced per unit, so a home with three or four split units will multiply from there. Ask each provider for a total price across all your units, not just the per-unit rate, since transport and call-out charges are often bundled differently.
Ask whether the quote is a chemical wash specifically, or a general service — the two are priced differently and do different things, and a provider who quotes one and performs the other is not giving you what the symptom needs.
Who to call, and how to judge them
An ACRA registration confirms the business exists; it does not confirm R32 training, so ask for that separately if your unit needs it.
Prefer a provider who asks about the symptom (cooling, smell, or leak) before quoting, and who names chemical wash rather than general service when that is what the symptom calls for.
Frequently asked questions
How do I know if my aircon needs a chemical wash instead of a general service?
An aircon needs a chemical wash when cooling has noticeably dropped, the unit smells musty when it starts, or water drips from the indoor unit — a routine general service cleans the filter and cover but does not reach the coil, so those symptoms usually mean it is time for the deeper job.
Why does my aircon smell musty when it starts?
A dirt-caked coil is the most common reason cooling drops off, and the same buildup that traps dust also traps moisture, which is why a dirty coil often produces a musty smell on start-up as well as weaker cooling. A general wipe-down of the filter does not reach this buildup; only a full chemical soak does.
Sources
- NEA, "About Mandatory Energy Labelling and MEPS" (fetched 15 Sep 2026)
- NEA, "Reducing GHG Emissions from the Use of Refrigerants in the RAC Sector" (fetched 15 Sep 2026)
- Daikin Singapore, "Air Conditioner Warranty" (fetched 15 Sep 2026)
Compare aircon servicing providers and give each the same three answers: the symptom, how long since the last chemical wash, and how many units.
