There is one sentence a technician can say that changes the size of the conversation completely: "the compressor is gone." Everything else on an aircon — a choked drain, a failed capacitor, a tired fan motor, a gas leak — is a repair. The compressor is the only component whose replacement cost gets close enough to a new system that you genuinely have to sit down and think.
It is also the diagnosis most often delivered with the least evidence. This is what the part actually does, how a real diagnosis is made, the three things that decide the answer before any price is discussed, and the arithmetic you can do at your own kitchen table.
What the compressor is, and why it is the expensive one
The compressor sits in the outdoor unit — the condenser on your ledge or at the back of the house. It is the pump that moves refrigerant around the system, and it is the only part of an aircon that is doing real mechanical work every second the unit is cold. The indoor units blow air. The compressor does the cooling.
Two things follow from that. First, it is the most heavily loaded part, so it is a genuine wear item on a system that has run for a decade in Singapore's climate. Second, it is sealed into the refrigerant circuit. Replacing it is not unplugging a module: the system has to be recovered, the old compressor cut out, the new one brazed in, the circuit vacuumed down and recharged, and the whole thing tested. That is a half-day of skilled work plus a part that is a substantial fraction of the unit's original price.
Which is why on our pricing page almost every line is a fixed published figure — $45 for a one-unit service visit, $80 for a standard drainage or electrical repair — and compressor or PCB replacement is the one line that says quoted on-site. Not because it is a chance to load a price on, but because until the pre-check has confirmed what actually failed, any number would be invented. If somebody quotes you a compressor price over the phone before seeing the unit, they are guessing, and you are the one carrying the guess.
A compressor diagnosis you should accept, and one you should not
"It's not cold and the outdoor unit is humming" is a symptom shared by a failed capacitor, a tripped overload, a blocked condenser coil, a bad contactor, low refrigerant and a dead compressor. Four of those are cheap. One is not. So the honest test of a diagnosis is whether anyone measured anything.
Before you agree that the compressor has failed, ask to be shown three things:
- The electrical readings. A technician checking a compressor takes current draw and winding resistance. A compressor that has gone open-circuit or short to earth shows it in those readings. This takes minutes and it is the difference between a diagnosis and an opinion.
- The capacitor. A failed run capacitor produces a compressor that hums, draws heavily and will not start — the exact symptom set people are told is a dead compressor. It is one of the cheapest parts on the machine. It should be eliminated first, out loud, in front of you.
- The pressures. A system starved of refrigerant will not cool, and a compressor running short of gas is a compressor being destroyed rather than one that has failed. If the pressures are low, the question is where the gas went — which is a leak repair conversation, not a compressor one. Our gas leak repair page sets out what that path looks like.
Every repair visit we do starts with the 9-point pre-check for exactly this reason. It is included with a service booking, and on a repair the $45 minimum covers the visit and the pre-check. The point of it is that the diagnosis is finished before any money is discussed.
The three things that decide it, before price comes up
1. Is the unit still inside its manufacturer's compressor warranty?
This is the first question and most owners never ask it. Compressors sold in Singapore commonly carry a manufacturer's five-year warranty on the compressor itself, separate from and longer than any warranty on the rest of the unit. When we install, we say so plainly: a 2-year installation warranty from us, on top of the manufacturer's 5-year compressor warranty on the units. We have written about how the two warranties differ and who honours which in what a workmanship warranty actually covers.
So before you accept a quotation to replace a compressor, find out how old the system is. If it is under five years, the part may cost you nothing and the conversation is about labour and gas only. You will need the installation date and the model and serial numbers off the outdoor unit — which is a good argument for keeping the original invoice somewhere you can find it.
Note the trap: a manufacturer's compressor warranty normally covers the part, not the labour, the refrigerant or the recovery. So "under warranty" rarely means free. It does usually mean substantially cheaper, and it changes the answer.
2. How old is the system, really?
A compressor that fails at four years is an unlucky machine. A compressor that fails at eleven is a machine telling you what stage it is at, and the fan motor, the PCB and the coils are all the same age. Spending heavily on one component inside a system where everything else is equally worn is the classic way to pay twice. We have set out how long these systems actually last in Singapore conditions in how long an aircon should last, and the wider repair-or-replace decision in when to replace rather than keep repairing.
3. What refrigerant is in it?
Look at the label on the outdoor unit. If it says R32, you have a current-generation system and parts and gas are ordinary. If it says R410A, you have a system of the middle era. If it says R22, you are looking at an old machine by definition — nothing has been sold new on R22 in Singapore homes for a long time — and you are about to put a major part into a system whose remaining life is short. You can see the difference in what the gas alone costs on our published rates: R32 top-up $170, R410A $130, R22 $115. Cheap gas is not a reason to keep an old system; the age is the signal.
The arithmetic, using numbers you can check
Here is the honest comparison, and you can do it before anyone quotes you.
On one side: the compressor quotation, which we give on-site after the pre-check, plus the reality that the rest of the system stays the age it is.
On the other side: a new system, at the prices we publish. A single split starts from $1,200 for a standard inverter. A System 2 starts from $2,200, a System 3 from $2,800, a System 4 from $3,500. Those are our published installation "from" figures and the full breakdown is on the installation cost page. A new system resets the clock on every component, comes with our 2-year installation warranty, and starts a fresh manufacturer's compressor warranty.
The rule of thumb that follows is simple and it is not a sales line: if the compressor job costs a large fraction of a new system and the system is past its middle age, replace the system. If the compressor job is a small fraction, or the unit is young, or the part is under manufacturer's warranty, fix it.
The case people get wrong is the middle: a System 3 where one indoor unit's outdoor compressor has gone at year eight. It feels wasteful to throw away three indoor units that still blow air. But those three indoor units are also eight years old, they share the same refrigerant circuit, and the drainage, trunking and piping are the same age too. Replacing one indoor unit on a live system is sometimes right — we have written about exactly that in replacing one indoor unit on a System 3 — but it is a different question from putting a new heart into an old body.
What actually kills compressors, and the part you control
Compressors rarely die of old age alone. They die of things that were happening for months:
- Running short of refrigerant. Refrigerant carries the oil that lubricates the compressor. A slow leak that nobody chased means a compressor that ran hot and under-lubricated for a long time before it stopped. This is the single most common preventable cause, and it is why "just top up the gas again" every few months is not a cheap option — it is an expensive one on a delay.
- A choked condenser coil. A coil packed with dust cannot reject heat, so the compressor works harder and hotter for the same cooling. This is the outdoor half of what servicing is for.
- Electrical supply problems. A failing capacitor or contactor makes a compressor start badly, repeatedly, for weeks.
- Short cycling. A unit that starts and stops constantly — often an oversized system, or a control problem — wears the compressor at the moment of highest stress.
The practical consequence: the two things that most extend a compressor's life are keeping the outdoor coil clean and never ignoring a system that needs gas twice. Neither is expensive. Both are ordinary servicing.
Four questions to ask before you sign anything
- What did you measure, and what were the readings? A real diagnosis produces numbers.
- Have you ruled out the capacitor and the contactor? If not, that comes first.
- What is the model and serial number, and how old is the unit? This is what decides the manufacturer's warranty question — and you should have it written on the quotation.
- Does the quotation include recovery, the new part, refrigerant, vacuum, recharge and testing — and what warranty comes with the work? A compressor quotation with no scope attached is a number, not a quote.
The short version
The compressor is the one aircon repair big enough to be a real decision. Do not accept the diagnosis without readings, and make sure the capacitor and the refrigerant charge have been eliminated first. Then answer three questions in order: is it inside the manufacturer's five-year compressor warranty, how old is the whole system, and what refrigerant is in it. Compare the on-site compressor quotation against our published installation prices rather than against a feeling. And whichever way you go, the thing that gets you the next ten years out of the next compressor is a clean outdoor coil and never letting a leak run.
Been told your compressor has failed and want a second opinion before you commit? WhatsApp us on 9107 2601 — tell us the brand, roughly how old the system is and what you were told, and we will tell you what to check before you spend anything. Every repair visit starts with the 9-point pre-check, and our published price list shows exactly which lines are fixed and which are quoted after diagnosis.