Checking the Aircon Before You Buy a Resale Flat in Singapore

Nobody views a resale flat and asks to see the aircon filter. You look at the layout, the kitchen, the light, the neighbours' corridor. Then you collect the keys, switch on the units in July, and discover that the previous owner's "recently serviced" aircon has a blower barrel packed solid and a drain line that starts dripping in week two. The aircon is one of the few things in a resale flat that can cost four figures within a month of moving in, and it is one of the easiest things to check properly before you commit.

This is what to look at during a viewing, what to ask the seller, and what the honest options are once the flat is yours.

Why the aircon is the item most often skipped

Two reasons. First, an aircon looks the same whether it is healthy or ruined — the casing hides everything that matters. Second, a unit that is filthy inside still blows cold air for a while, so a two-minute test during a viewing proves almost nothing.

What actually decays is the part you cannot see: the coil and the blower barrel. In Singapore's humidity, which averages around 84%, dust binds into a biofilm on wet surfaces and hardens layer by layer. A unit that has run for years on filter-rinsing alone can look spotless from the front and be black behind the cover. That is the state that turns into a leak, a smell, or a compressor working far harder than it should.

The five-minute check you can do at a viewing

You are not doing a technical inspection at someone else's home, and you should not be dismantling anything. But five minutes of looking tells you a great deal.

• Open the front cover and look at the filter. The cover flips up on almost every wall-mounted unit and putting it back is no harder. A grey filter is normal. A filter with a felted mat on it, or one that is clean while the fins behind it are dark, tells you it was rinsed for the viewing and nothing more.
• Look past the filter at the fins. Silver-grey aluminium is fine. Dark brown or black, or fins with visible fluff bridging between them, means the coil has not had a proper clean in a long time.
• Run every unit for a few minutes and stand under it. A sour, vinegary or musty smell in the first minutes is mould and biofilm, not a passing odour. It does not clear with use.
• Listen with the room quiet. Rattles, a rhythmic tick, or a bearing whine from the indoor unit are worth noting. So is an outdoor condenser that sounds rough or vibrates against its bracket.
• Look for water marks. Staining on the wall under the unit, a bulge or bubbling in the paint, or a discoloured patch of ceiling near the trunking means the drainage has overflowed at some point. Around nine in ten aircon water leaks come down to a blocked condensate drain, so it is usually a fixable problem — but you want to know it exists before you own it.
• Check the outdoor units. On an HDB flat they sit on the aircon ledge. Look for heavy rust on the casing or the bracket, and for units stacked or wedged into a space that leaves no room to work. Access is what makes future servicing cheap or expensive.

If the flat has a ledge that has been enclosed, altered, or is carrying more units than it looks designed for, that is worth understanding properly before you buy — we set out what HDB allows in the guide to aircon ledges.

The four questions to ask the seller or the agent

Ask them in writing, through the agent, and keep the reply.

1. How old are the units? Not "quite new" — a year. The install date usually appears on a sticker on the indoor unit or in the installation invoice. Age is the single most useful number you can get.
2. When was the last service, and what kind? A general service and a chemical wash are different jobs. "Serviced recently" without an invoice naming the work performed and the number of units means nothing.
3. Has any unit had gas topped up, and why? A top-up because a system has slowly lost charge over many years is upkeep. A top-up because there is a leak in the piping is a fault in the property, and it will come back.
4. Are all units working today? Ask it directly, because "we don't use that room" is not the same answer.

None of these questions oblige anyone to answer, and a seller who declines is not necessarily hiding something. But the pattern of the answers tells you what you are taking on, and it costs nothing to ask.

What it costs to put things right after handover

This is the part worth budgeting before you negotiate, not after. Our prices are published in full on the pricing page, and the displayed price is the final price:

• General servicing — $45 for 1 unit, $70 for 2, $95 for 3, $115 for 4, and $25 per unit from 5 units. This is routine three-monthly upkeep, not a rescue.
• Chemical wash — $135 for 1 unit, $245 for 2, $345 for 3, $425 for 4, and $100 per unit from 5 units. This is the deeper coil clean, and it is usually what a neglected unit actually needs.
• Chemical overhaul — $200 for 1 unit, $370 for 2, $515 for 3, $640 for 4, and $150 per unit from 5 units. Full disassembly and individual cleaning of every component, for units that are badly fouled.
• Gas top-up — from $115 for R22, from $130 for R410A, from $170 for R32.
• The 9-point pre-check comes with every booking, minimum $45 for one unit, covering the visit, the inspection and standard servicing. Anything beyond that is quoted before it is done.

The honest way to read that list: a System 3 that has been neglected is more likely to need a chemical wash than a general service, and the difference between the two is the number worth carrying into your renovation budget. The full comparison is in what a chemical wash costs and the symptom-by-symptom version in signs your aircon needs a chemical wash.

When the answer is replacement, not cleaning

Sometimes the cheapest path is a new system, and pretending otherwise wastes your money on a unit that will not survive the year. The questions that decide it are how old the units are, whether the refrigerant is a type still commonly serviced, whether the piping and trunking are in usable condition, and whether the fault is dirt or a failing compressor.

Old flats bring a specific complication: existing copper piping and trunking may not suit a modern system, and reusing it is not always possible. We go through that in replacing aircon in an older HDB flat, and the repair-or-replace decision itself in when to replace rather than keep repairing. If replacement is the answer, our published installation prices start from $1,200 for a single split, $2,200 for a System 2, $2,800 for a System 3 and $3,500 for a System 4, with the full breakdown on the installation cost page.

The order to do things in after you get the keys

Most people book aircon servicing after the renovation, when they are already living in the flat. That is the wrong way round.

1. Book a pre-check before renovation works start, while the flat is empty. It is the cheapest time to find out what you have, and an empty flat means unrestricted access to every unit and to the ledge.
2. Decide keep-or-replace before the carpentry goes in. Boxing in trunking or building a false ceiling around a unit you are going to remove in eight months is an expensive sequence.
3. If keeping the units, do the deep clean after the dusty works finish, not before. Hacking and sanding will undo it otherwise.
4. Then start the three-to-four-month servicing cycle from a known clean baseline. Your maintenance history begins on the day you take over, and it is the record that protects you if you ever rent the flat out or sell it. How often to service covers the intervals.

What you are actually buying with a pre-check

Every booking starts with the 9-point pre-check before any work begins: power and thermostat test, temperature drop measurement, compressor pressure reading, drainage flow check, outdoor condenser inspection, fan blower spin test, damage and corrosion check, filter and coil dirt assessment, and an operating noise diagnostic. The point is to establish what is actually wrong before anyone quotes for fixing it.

For a flat you have just taken over, that is exactly the document you want: a written statement of the condition of every unit on day one. It tells you what to budget, and it gives you a baseline to measure against in three years.

Get the units checked before you renovate

Tell us the flat type, how many units, and roughly how old they are if you know. If you have just collected keys and the flat is empty, say so — that is the easiest visit to schedule and the most useful one to have.

WhatsApp 9107 2601 for a resale flat aircon check →

Related reading: how long an aircon should last in Singapore · what HDB allows on an aircon ledge · why aircons leak water and how to stop it