How Your Air Conditioner Works
1. How cooling works
In cooling mode, the system removes heat from the air inside your home and releases it outdoors.
| Stage | What happens |
|---|---|
| 1. Indoor air is drawn in | A fan pulls warm room air through the indoor unit and across a cold heat exchanger, commonly called the evaporator coil. |
| 2. Heat is absorbed | Refrigerant inside the coil absorbs heat from the air. The cooled air is then circulated back into the room. |
| 3. Heat moves outdoors | The compressor circulates the refrigerant to the outdoor unit and raises its pressure and temperature. |
| 4. Heat is released | The outdoor coil releases the collected heat into the outside air. The refrigerant then returns indoors and the cycle repeats. |
2. Main system components
| Component | Purpose |
|---|---|
| Indoor unit | Circulates room air across the indoor heat exchanger. In cooling mode, it absorbs heat and also removes some moisture from the air. |
| Outdoor unit | Contains the compressor and outdoor heat exchanger. In cooling mode, it releases heat outdoors. |
| Compressor | Pumps refrigerant around the sealed system and creates the pressure difference needed to transfer heat. |
| Refrigerant pipework | Carries refrigerant between the indoor and outdoor units. |
| Expansion device | Controls refrigerant flow and reduces its pressure before it returns to the indoor heat exchanger. |
3. How reverse-cycle heating works
In heating mode, a reverse-cycle air conditioner changes the direction of refrigerant flow. The outdoor unit absorbs heat from the outside air and transfers it indoors.
During cold or humid weather, frost may form on the outdoor heat exchanger. The system may temporarily enter a defrost cycle to remove it. Indoor airflow can pause during this process, which is normal.
4. About refrigerant
Refrigerant is the working fluid that allows the air conditioner to absorb, carry and release heat. It changes pressure, temperature and physical state as it circulates through the sealed refrigeration system.
- Older refrigerants, including CFCs and HCFCs, damage the ozone layer and have been progressively phased out.
- Many current systems use HFC refrigerants, including R32. HFCs do not deplete the ozone layer, but they can contribute to global warming if released.
- Australia is progressively reducing bulk HFC imports, while lower-global-warming-potential technologies continue to be introduced.
- Existing equipment does not need to be replaced solely because its refrigerant is subject to a phase-down.
5. Why water may come from the system
When warm, humid indoor air passes over the cold indoor heat exchanger, moisture condenses into water. This water is collected in a drain pan and discharged through the condensate drain.
Water flowing from the indoor unit is not normal and may indicate a blocked drain, incorrect installation or another issue requiring inspection. Water draining from the outdoor unit can be normal, particularly during heating and defrost operation.
6. Keeping the system effective
- Clean the indoor air filters regularly.
- Keep indoor and outdoor air inlets and outlets clear.
- Close doors and windows while the system is operating.
- Use a practical set temperature rather than setting the controller to its minimum or maximum value.
- Arrange professional inspection if performance changes, unusual noises occur or an error code is displayed.