The short answer
Switch the unit off, lift the front panel and take out the mesh filters, then vacuum or rinse them in lukewarm water and let them dry fully before refitting. In regular use, this usually needs doing every few weeks.
On this page
The filters sit just behind the front panel of the indoor unit, catching dust, fluff and pet hair before they reach the coil and fan. They are the one part of the unit designed for you to take out, and cleaning them needs no tools.
What dirty filters do
As a filter clogs, less air gets through it. The system has to work harder to reach the temperature you set, rooms take longer to cool or warm, and the air from the vents feels weaker.
In cooling mode, a badly blocked filter can let the coil get cold enough to ice over. When that ice melts, the water can overflow and drip into the room, which is covered in water dripping from the indoor unit.
Dust that slips past a torn or missing filter settles on the coil and fan, where you can't reach it. Cleaning those is part of a service.
How often to clean them
Filters usually need cleaning every few weeks while the system is in regular use. Your manual gives the interval for your model, and many units light a filter reminder after a set number of running hours.
| Your home | How often to check |
|---|---|
| Daily use in summer or winter | Every two to four weeks |
| Pets, building work or a dusty room | Every week or two |
| Occasional use | Every month or so while in use |
| Not used for a few months | Before switching it back on |
Cleaning them step by step
Indoor units are mounted high on the wall, so use a steady step ladder rather than a chair.
- Switch the unit off with the remote and wait for the louvres to close. If your manual also says to cut the power, use the isolator switch or the circuit breaker for the system.
- Lift the front panel. On most wall units it lifts from the bottom edge until it stops or clicks into place. The manual shows how on yours.
- Take out the filters. There are usually two mesh panels. Hold each one by its tab or frame and ease it out gently, without forcing it.
- Vacuum the dusty side with a soft brush attachment. If that isn't enough, rinse the filters under lukewarm running water from the back, so the dust washes out the way it came in.
- For greasy filters, such as those in a room with a cooker, use a little mild washing-up liquid, then rinse well. Avoid hot water, bleach, solvents and stiff brushes, which can distort or tear the mesh.
- Shake off the water and let the filters dry completely, in the shade and away from radiators and direct sun, which can warp them.
- Slide them back into their guides, check they sit flat, and close the panel until it clicks.
- Reset the filter light if your unit has one. The manual gives the button or menu.
While you're there, you can wipe the outside of the casing with a soft, damp cloth. Don't use polish or abrasive cleaners on it.
Other kinds of filter
Some units have an extra, finer filter clipped to the mesh filters or sitting behind them, designed to catch finer particles or reduce odours. These are often replaced rather than washed, on a schedule given in the manual, so check which kind you have before getting it wet. What air conditioning filters do explains the different types.
Some models clean their own mesh filters automatically. They still need occasional attention, such as emptying a dust box, so check the manual for what yours needs.
Ceiling cassettes, floor-standing units and ducted systems have filters too, usually behind a grille that opens. Their manuals show how to reach them.
What to leave alone
- Don't run the system with the filters out. Dust goes straight onto the coil.
- Don't touch the metal fins of the coil behind the filters. They are thin, sharp and easily bent.
- Don't spray cleaners, disinfectants or air fresheners into the unit.
- Don't remove anything beyond the front panel and the filters.
If clean filters don't bring back the airflow, or a stale smell lingers, the cause may be further inside the unit, such as a dirty fan or coil. Musty or unusual smells explains what to check for a smell and when a service is the answer.
Related guides
- What air conditioning filters doAir conditioning filters catch dust and fibres before they reach the indoor unit's coil and fan, keeping air flowing freely and the inside of the unit cleaner. Most are washable mesh screens that need cleaning every few weeks in regular use.
- What a service involvesA service is a clean and check of the whole system, indoors and out, plus tests of how it runs and a look for leaks and wear. Manufacturers typically recommend one regularly, often once a year.
- Musty or unusual smellsA musty smell usually comes from damp dirt on the coil, drain tray or fan, and a dusty smell when heating first starts usually fades. A burning or electrical smell means switching the system off straight away.
- Not cooling or heating properlyStart with the simple causes: the mode and setting on the remote, timers, dirty filters, open windows and a blocked outdoor unit. If those are fine and it still struggles, it may have a fault or leak that needs an engineer.