The compressor is the pump at the centre of the refrigeration circuit, and it lives in the outdoor unit. It takes low-pressure refrigerant gas returning from the indoor coil, compresses it, and pushes it out hot and high-pressure to the condenser. Everything else in the system — the coils, the fans, the expansion valve — is arranged around that one action. When the compressor stops working, the fans keep turning and the unit keeps blowing, but the air coming out is room temperature. That is the single most common way an aircon fails in a way the owner notices.
Why compressors fail
Very few compressors simply wear out. Most are killed by something upstream. A slow refrigerant leak leaves the compressor running with too little gas to cool itself, and it overheats. A blocked condenser coil — common on the coast, where salt and dust bind into the fins — raises head pressure until the motor draws more current than it should. A failed start capacitor leaves it straining against a load it cannot turn. In each case the compressor is the part that dies, but replacing it without finding the cause simply buys a few months.
Repair or replace
A compressor is the most expensive single component in a split system, and on a unit more than about eight years old the honest answer is often that a replacement unit costs less than a compressor swap plus the labour to recover, evacuate and recharge the system. We will tell you which side of that line your unit falls on before any work starts, and we will say so plainly if the sensible decision is to replace rather than repair.
What we check first
Before condemning a compressor we measure supply voltage at the unit, test the run and start capacitors, check the contactor for pitted or welded contacts, and read suction and discharge pressures. A surprising number of no-cooling call-outs that look like compressor failure turn out to be a capacitor worth a fraction of the price, or a contactor that is not pulling in. Diagnosing in that order is the difference between a same-day fix and an unnecessary quote for a new system.
Brands we fit and service
The compressor market splits into hardware built for South African conditions and lookalikes that fail at the first hard season. These are the manufacturers we trust on our installations:
- Samsung
- LG
- Midea
- Hisense
- Daikin
- Alliance
- Defy
See our brand guides for how these manufacturers compare.
When the compressor goes wrong
These are the failures we're called to most often — each with its symptoms, causes and our fix on the dedicated problems page:
- Unit runs but never gets cold — The indoor unit powers on, the fan runs and the remote responds, but the air coming out is room temperature or barely co…
- Outdoor unit trips the breaker when it starts — The unit works for a moment and then the circuit breaker trips, usually at the instant the outdoor compressor tries to s…
- Loud humming from the outdoor unit with no start — The outdoor unit hums or buzzes audibly but the compressor never spins up. After a few seconds the internal overload cut…
Need this fixed or installed?
Our Aircon Repairs service covers compressor work — from R650, quoted upfront and backed by our 12-month workmanship warranty.