Cleaning the filters is the single most useful maintenance job a homeowner can do on a split system air conditioner, and it takes about ten minutes. In Brisbane, where air conditioners can run for months on end, clogged filters are behind a surprising number of poor performance complaints and avoidable service calls.
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Why filter cleaning matters
The filters catch dust, pet hair and airborne grit before it reaches the indoor coil. When they clog, airflow drops, the unit works harder to cool the room, and the coil can ice up or leak water. Dirty filters also hold moisture and dust that contribute to the musty smell many people notice at start-up, which we cover in our guide to air conditioner musty smells.
How often to clean them
- Heavy use (daily in summer): every 4 to 6 weeks
- Normal use: every 2 to 3 months
- Homes with pets, smokers or near a busy road: more often, as dust loads are higher
Step-by-step cleaning
- Turn the unit off at the remote and, ideally, at the wall isolator.
- Open the front panel of the indoor unit and gently lift out the filters. Most slide out without tools.
- Vacuum off loose dust first, using a soft brush attachment.
- Wash in lukewarm water with a little mild detergent. Never use hot water or harsh chemicals, as they can warp the mesh.
- Rinse well and leave them to dry completely in the shade. Do not refit damp filters.
- Refit the filters and close the panel, then run the unit on fan mode for a few minutes.
What not to do
Don’t spray water into the indoor unit, don’t remove anything beyond the filters and front panel, and don’t run the unit without filters. If you can see mould on the coil or the fan, or the unit is leaking water, that’s a job for a technician rather than a DIY clean, because the coil and drain need proper cleaning. See our guide on why air conditioners leak water.
Signs your filters need attention
- Weak airflow from the indoor unit, even on a high fan speed
- Rooms taking longer than usual to cool down
- Visible dust or grey build-up on the filter mesh
- A stale smell when the unit starts
- Higher power bills with no change in how you use the system
If any of these sound familiar, cleaning the filters is the first thing to try, and it costs nothing.
Brisbane conditions that make it worse
Brisbane’s mix of humidity, summer storms and spring pollen means filters collect more than you might think. After bushfire smoke events, strong winds or nearby building work, dust loads can spike quickly. If you’ve had renovations or sanding done in the house, check the filters straight away, because fine dust clogs the mesh faster than anything else.
Ducted systems
Ducted air conditioning has return air filters at the ceiling grilles or in the ceiling space. Many can be cleaned in a similar way, but access often needs a ladder, so take care. If you can’t safely reach the filter, a licensed technician can do it as part of a service.
When filter cleaning isn’t enough
If the system is still weak, noisy or smelly after the filters are clean, the cause may be a dirty coil, a refrigerant issue or a failing component. Our guide to an air conditioner not cooling covers the common causes. A regular professional service, as discussed in how often to service your air conditioner, handles the parts you can’t reach.
Does a clean filter save money?
Yes. A clean filter lets the unit move air freely, so the compressor doesn’t have to run as hard or as long to reach the set temperature. Over a Brisbane summer, that adds up to a noticeable difference in running costs, and it reduces wear on the fan motor and compressor, which are the most expensive parts to replace. Pairing regular filter cleaning with sensible settings, as covered in our summer energy saving tips, is the cheapest way to keep your system efficient.
Need a hand?
Integrated Trade Services is a licensed, ARCtick-accredited air conditioning contractor servicing Brisbane and Moreton Bay. Visit our air conditioning service page or contact us to book a service or ask a question.