What to check first
Ask yourself what actually prompted the call: a musty smell, water leaking from the indoor unit, cooling that is weaker than it should be, or simply that it has been years since anything beyond routine servicing was done. Each points differently to whether a wash or an overhaul is the right job.
Check whether a chemical wash has already been done recently and did not fix the problem — that is the strongest single signal that an overhaul, not a repeat wash, is needed. If you are not sure what was done last time, check your last invoice for the job name before you call.
Note whether the water leakage or smell affects one indoor unit or several. A single unit with a blocked drain pan is a smaller job than several units that have never had a strip-down.
The likely reasons an overhaul is needed, in order
A chemical wash no longer works (most common). The most likely reason an overhaul is needed is that a chemical wash no longer restores cooling or stops a musty smell, which means contamination has built up in places a wash cleaning in place cannot reach. Safe check: none beyond noting that a wash was tried and did not solve it — the parts need to come out, which is not a DIY step.
Recurring water leakage after a wash. The second likely reason is recurring water leakage from the indoor unit after a wash, since a blocked or contaminated drain pan and fan often need to come out to be cleared properly rather than flushed in place. Safe check: note how soon after the last service the leak returned; a leak within weeks points more strongly to this.
Years without a strip-down. The third reason is simply time and use: a unit that has had general servicing or a chemical wash but never a full strip-down in several years of heavy use in Singapore's humidity accumulates contamination a surface clean does not reach. Safe check: work out roughly how long it has been since the last deep clean, not just the last routine service.
When to call, and how urgently
This is rarely an emergency. A unit that needs an overhaul is usually still cooling, just not as well as it should, or carrying a smell rather than a fault. Book within a few weeks rather than the same day, unless the water leakage is damaging flooring or furniture, in which case treat that part as urgent.
Do not let a provider talk you into an overhaul without first trying a wash, if a wash has not already been tried and failed — ask why the deeper job is needed rather than the cheaper one.
What it costs
The gap reflects the extra labour of removing and reassembling the parts, not just a different name for the same job.
What to check before booking: ask whether a wash has already been tried and failed, how many indoor units need the overhaul, and whether the outdoor unit is included — a fair quote separates these rather than bundling them into one flat number. Ask what happens if the smell or leak returns after the overhaul, since that should not happen if the job was done properly.
Who to call, and how to judge them
NEA requires suppliers to register regulated goods before supplying them and mandates GHG entity registration for companies performing maintenance and installation work, with certified technicians carrying out the job. There is no public register a homeowner can search by company name for this specific job, so ask directly.
An ACRA registration confirms the business exists, nothing more. Prefer a provider who explains what an overhaul actually involves, over one who uses "overhaul" and "wash" interchangeably in the quote. On arrival, a provider doing a proper overhaul removes the coil, fan and drain components rather than spraying chemical solution over an assembled unit, which is the actual difference between an overhaul and a wash.
Frequently asked questions
What is the difference between a chemical wash and a chemical overhaul?
An aircon chemical overhaul is a full strip-down clean of the indoor unit — the coil, fan and drainage parts are removed, soaked and cleaned individually — rather than cleaned in place the way a routine chemical wash cleans them.
How do I know I need an overhaul instead of a wash?
The most likely reason an overhaul is needed is that a chemical wash no longer restores cooling or stops a musty smell, which means contamination has built up in places a wash cleaning in place cannot reach.
Why does an overhaul cost more than a wash?
An overhaul takes the unit apart and cleans the parts separately, so it takes longer and needs more labour than a wash. Ask each provider what is dismantled and what is included before you agree a price.
Sources
- Daikin Singapore, "Air Conditioner Warranty" (fetched 15 Sep 2026)
- NEA, "Reducing GHG Emissions from the Use of Refrigerants in the RAC Sector" (fetched 15 Sep 2026)
- NEA, "About Mandatory Energy Labelling and Minimum Energy Performance Standards" (fetched 15 Sep 2026)
Compare aircon servicing providers and ask whether a wash has been tried before you agree to the more expensive overhaul.
