Knowing how your Air Conditioning system components works
A split air conditioning system is made up of several parts working together — grouped into two separate systems, indoor and outdoor. Each system has one or two major components plus a few supporting parts, while the control components sit with the indoor unit. Knowing what each part does can come in handy when something goes wrong, and helps you understand what a technician means when they explain a fault.
How the Refrigeration Cycle Works
Air conditioners don’t create cold air — they move heat out of your home. Refrigerant flows in a loop between the indoor and outdoor units, changing between liquid and gas to absorb and release heat at each stage. Australia’s energy.gov.au explains this well: the same refrigeration cycle can move heat out of your home in summer, or reverse to move heat into it in winter, which is how a reverse-cycle system heats and cools with one unit.
The indoor system is the low-pressure side of the cycle. Its major components are the evaporator, a cooling fan, and a drainpipe. The evaporator — coiled tubing — absorbs heat from the room as refrigerant liquid turns to gas inside it. The cooling fan blows that cooled air into the room while drawing warm air across the coils to keep the cycle going.
The outdoor system is the high-pressure side, and acts as the heat exchanger that removes heat before cooled air returns to the room. Its major components are the compressor, condenser, condenser fans, and expansion valve — covered in detail below.
The Outdoor System Components
Compressor
The compressor circulates refrigerant vapour by compressing it and raising its temperature before sending it to the condenser. There are several types — reciprocating, centrifugal, screw, scroll, and rotary — and which one a system uses depends on the cooling load it needs to handle. Larger commercial systems tend to use centrifugal compressors, while scroll and rotary compressors are most common in residential split systems.
Condenser
The condenser turns the high-pressure refrigerant vapour from the compressor back into a liquid by removing heat from it. That heat is released outside, and the now-cooled liquid moves on to the expansion valve. The condenser works much like a car radiator, with multiple coils sized to match the compressor and the overall capacity of the unit.
Condenser Fans
Once the condenser has pulled heat out of the refrigerant, the condenser fans expel that heat outside. If this heat isn’t expelled properly, it can return to the compressor, causing overheating and reducing the system’s efficiency — which is why keeping the outdoor unit clear of debris matters.
Expansion Valve
The now-cooled refrigerant liquid passes through the expansion valve, which lowers its pressure and, with it, its temperature. This low-pressure liquid then moves into the evaporator coils to start the cycle again.
Other Essential Components
Refrigerant — The fluid inside the coils that carries heat through the system as it cycles between liquid and gas. It’s engineered with a boiling point low enough to evaporate easily as it absorbs heat in the evaporator, then condense back to liquid once the compressor raises its pressure.
Tubes and Tube Insulation — Refrigerant moves between the condenser and evaporator through tubing insulated with synthetic rubber, which helps maintain refrigerant temperature as it travels between components.
Air Filter — Located in the indoor unit, the air filter cleans air before it passes over the evaporator coil, trapping dust and odours. Filters are disposable or reusable and should be cleaned or replaced regularly — check monthly during heavy use.
Muffler — Reduces compressor noise by cancelling out sound waves. Generally only needed on larger units or compressors with more moving parts.
Casing and Casing Parts — The outer shell of the unit, protecting internal components from dust, dirt and weather.
Drainpipe — Removes the excess liquid produced during condensation. On ducted or centralised systems, this may connect to your home’s plumbing or drainage system, helping maintain efficiency by draining excess water as it forms.
The Control Parts of a Split System
The control parts switch the system on and off and manage how hard it works. In a wall-mounted split system, the main ones are the thermostat and contactor, with a humidistat included on some models. The thermostat measures room temperature and, once it reaches the set point, signals the contactor to begin heating or cooling. The contactor acts as the switch, turning the compressor on or off based on that signal. Where fitted, the humidistat detects humidity levels and helps the thermostat judge how much work the system needs to do to keep the room comfortable — not every split system includes one, and units with a humidistat typically cost more than those without.
Note: dampers, which direct airflow through duct openings, are a feature of ducted air conditioning systems rather than wall-mounted split units.
Conclusion
An air conditioner is a system of multiple parts working together — if one component fails, it may not stop the unit completely, but it will usually stop it cooling or heating effectively. If you’re noticing reduced performance, unusual noise, or a system that won’t switch on, it’s worth getting it looked at before a minor fault turns into a bigger repair.
Whether you need a routine service or suspect a fault, Rite Price’s repair team can diagnose the issue and get your system running properly again.
