Aircon Compressor
The compressor is the most expensive part in your aircon. It is also one of the most frequently misdiagnosed. Proper assessment needs data, not just symptoms.
What This Part Does
Your aircon cools a room by moving heat out. The compressor makes that possible.
It pumps refrigerant through the system. Refrigerant absorbs heat from your room and releases it outside.
Without the compressor pumping properly, your aircon cannot move heat. The fan still blows. The room stays warm.
How You Would Notice
The most common experience: the aircon runs, fan blows, but the room never cools down.
Other signs include a humming sound from the outdoor unit followed by a click and stop — the compressor trying and failing to start.
In some cases the unit trips the circuit breaker on startup.
- Airflow feels normal but cooling never arrives
- Outdoor unit hums briefly then cuts off
- Breaker trips when the aircon starts
It Might Not Be The Compressor
A weak run capacitor causes the same hum-click-stop pattern. The capacitor supports compressor startup. When it fails, the compressor cannot start — even if the compressor itself is fine.
A faulty outdoor PCB can also block compressor operation. The compressor looks dead when the control board is not driving it.
You cannot tell these apart from the outside. We can.
How We Check
We start with the start circuit — not the compressor.
First, we test the run capacitor. If it is weak, we replace it and retest before going further.
If the start circuit is fine, we test compressor pumping under load. Pressure readings and refrigerant temperatures show whether the compressor is doing its job.
Both checks have to point to the same conclusion before we recommend replacement.
What We Find And What Happens Next
We only recommend compressor replacement when start circuit checks are clear and pumping data confirms failure.
| Finding | Next Step |
|---|---|
| Run capacitor out of range | Replace capacitor, retest cooling |
| Capacitor fine, compressor not pumping | Compressor replacement discussion |
About The Repair
Compressor replacement is a major job. It is the most expensive repair on a split aircon.
For most units, the decision is not just about the compressor — it is about whether the system is worth keeping. We factor in system age and reliability risk before recommending it.
If a technician quotes compressor replacement without running start circuit and pumping tests first, ask what was actually measured.
After Replacement
A replaced compressor with a healthy system should give years of reliable cooling.
If cooling problems return within months of replacement, the root cause may not have been the compressor. The diagnosis needs to be revisited.
We check refrigerant charge and system pressure after every compressor replacement to confirm the system is ready.
When We Tell You To Wait
If your aircon is cooling — even if inconsistently — we will tell you that on-site.
Not every startup issue needs immediate major repair. Some start circuit faults are a staged progression. We will give you an accurate picture of the risk before you decide.
Our job is to tell you what we found. Not to find something to fix.