Why filters matter
Every bit of air your system cools or heats passes through its filters first. They catch dust, pet hair, pollen and other particles before they reach the coil. When they clog, airflow drops, the system runs longer to reach temperature, and the coil and fan get dirtier, faster.
Signs your filters need attention
- Weaker airflow from the indoor unit or vents
- Rooms taking longer to cool or heat
- A musty or dusty smell when the system starts
- More dust settling around the house
- Allergy symptoms that get worse when the air conditioning is on
- A visible grey layer when you open the filter cover
- Power bills rising without a change in how you use the system
How often to check them
As a general rule, check and clean your filters every three months. Check them monthly during heavy summer use, or if you have pets, someone in the house with allergies, or live near a busy road or building site.
Split systems
Most split system filters are washable mesh panels behind the front cover of the indoor unit. With the system switched off, lift the cover, slide the filters out, vacuum or rinse them in lukewarm water and let them dry completely in the shade before refitting. Never run the unit without its filters in place.
Ducted systems
Ducted systems usually have a filter behind the main return air grille in the ceiling or a wall. Some are washable and some are disposable. Because the grille is overhead, many owners prefer to have the filter handled as part of a regular service.
Clean or replace?
Washable filters can be cleaned many times, but replace them if they are torn, warped or no longer seal properly in their frame. Disposable filters should be replaced rather than cleaned. If you are not sure which type you have, your technician can show you at your next service.
When to call a technician
Clean filters are not the whole story. If the smell, weak airflow or poor performance continues after you have cleaned them, the coil, fan or drain may need a professional clean, or there may be a fault. A regular service covers the parts you cannot reach and picks up small issues early.