ACcleanQLD · DIY Maintenance Guide
How to Clean Your Air Conditioner Filters
A 20-minute, step-by-step routine for cleaning split system AC filters safely at home. Written for Cassowary Coast homeowners — humid air, year-round use, and all the dust that comes with it.
Why does cleaning your filters matter in the tropics?
In Far North Queensland, dust, salt air and humidity clog aircon filters far faster than they do down south. A blocked filter makes the unit work harder for less cool air, and it lets dust and damp settle on the coil behind it — exactly where mould likes to start.
This guide covers standard wall-mounted split systems, the most common aircon in Mission Beach, Tully, Innisfail and the wider Cassowary Coast. Ceiling cassettes and ducted systems are best left to a technician. If the unit is really struggling, our guide on whether to clean, repair or replace will help you decide the next step, and our aircon cleaning services page lists what a full clean includes and what it costs.
Before you start — safety first
- Turn the unit off at the remote and at the wall isolator. Don't trust the remote alone.
- Wait 60 seconds after switching off — internal flaps and the swing louvre finish moving.
- Use a stable step stool, never a chair, and have someone hold it for high-mounted units.
- Don't spray water or aerosol cleaners into the unit. Filters come out to be cleaned.
- If the unit hums, sparks, or you see scorch marks anywhere on the housing, stop and call a technician.
What you'll need
- Soft-bristle brush or a clean microfibre cloth
- Vacuum cleaner with a brush attachment
- Lukewarm water — and a drop of mild dish soap if filters are greasy
- A clean towel for air-drying
- Step stool (most splits sit 2.1–2.4 m off the floor)
The step-by-step process
Step 1 — Turn the power off
Switch the unit off at the remote first, then flick the isolator switch on the wall next to the indoor unit (or trip the breaker on the switchboard if there's no isolator). This is non-negotiable — opening a powered unit risks the fan spinning up while your hands are inside.
Step 2 — Open the front cover
Almost every wall-mounted split has a hinged front fascia. Place your fingers in the small indents on each end of the panel and lift gently upward. The fascia usually clicks into a hold-open position around 60°. If it doesn't move easily, check for a second clip near the centre — don't force it.
Step 3 — Slide the filters out
Most units have two flat plastic-mesh filters that slide downward and out. Note which side faces the room — they need to go back in the same orientation. Take a photo on your phone before removing them if you're unsure.
Step 4 — Vacuum the loose dust
Take the filters outside or to a laundry sink. Vacuum each one on the dirtier (room-facing) side first using a soft brush attachment. Removing the dry dust now stops it turning into mud when you rinse the mesh.
Step 5 — Rinse with lukewarm water
Hold each filter under a lukewarm tap from the clean (coil-facing) side, so water pushes dust back the way it came in. Work the mesh gently with a soft brush. If filters are greasy — common in open-plan kitchens — add a single drop of mild dish soap, then rinse thoroughly so no soap film is left to attract dust later.
Avoid: bleach, eucalyptus oil, hot water above ~40 °C, or any hard scrubbing — all of them weaken the mesh and shorten filter life.Step 6 — Air-dry fully (this matters)
Lay the filters flat on a clean towel out of direct sunlight. Allow 2–4 hours in dry weather, longer in tropical humidity. Reinstalling damp filters traps moisture against the coil — and a damp coil with dust on it is the kind of environment mould tends to grow in. If you only remember every few weeks, keep a spare set of filters and rotate.
Step 7 — Wipe the louvres and fascia
While the filters dry, wipe the front louvres, fascia, and the visible inside lip of the housing with a damp microfibre cloth. Don't reach further inside than you can see — the aluminium coil fins behind the filters bend with the lightest touch and cost you airflow once damaged.
Step 8 — Reinstall and test
Slide each filter back in its original orientation, close the fascia until it clicks, then restore power at the wall and the remote. Run the system on fan-only for ten minutes — airflow should feel even, with no musty smell. Then switch to cooling.
Never spray water or aerosol cleaners into the aircon itself. Water on the electronics or coil can cause damage or an electrical fault. Filters only, in the sink.
A quick maintenance schedule
- Every 4–6 weeks (Oct–Apr): Rinse the filters.
- Every 2–3 weeks: If you have pets, smokers, or allergy sufferers in the home.
- After each long cooling run: Switch to fan-only for 10–15 minutes to dry the coil.
- Every 12 months: Book a professional deep clean of the coil and blower wheel — filter cleaning can't reach either.
- Every 6 months: If the system runs year-round or anyone in the home has asthma.
When to call a professional
Filter cleaning handles surface dust. Anything past the filter slot needs trained hands. Book a deep clean when you notice:
- Musty "dirty sock" smell for the first 10–15 minutes after start-up
- Visible black or green specks on the louvres or coil fins
- Water dripping from the indoor unit (blocked drain)
- Allergy or asthma symptoms that seem to flare indoors and ease outside
- It's been 12+ months since the last professional service
Mould and microbial growth in an indoor unit may aggravate symptoms for sensitive people, so it's worth dealing with rather than living with. Our companion guides cover mould in your aircon and why an aircon smells musty.
Past the filter? Book a deep clean.
We pull, wash and sanitise the parts homeowner cleaning can't reach — coil, blower wheel and drain — across the Cassowary Coast and Far North Queensland. See what's included and what it costs on our aircon cleaning services page.
Frequently asked questions
How often should I clean my split system AC filters in Far North Queensland?
Every 4–6 weeks during the cooling season (October to April). Households with pets, smokers or allergy sufferers should rinse them every 2–3 weeks. Outside cooling season, a quick check every 2 months is enough.
Can I wash AC filters with soap?
Lukewarm water and a soft brush is usually enough. If filters are greasy (common in kitchens), a drop of mild dish soap is fine — rinse thoroughly afterwards so no residue is left to attract dust. Never use bleach, solvents or boiling water; they degrade the mesh.
How long do AC filters take to dry?
Air-dry on a towel out of direct sunlight for 2–4 hours, depending on humidity. Reinstalling damp filters traps moisture against the coil, which is the kind of damp, dusty environment mould tends to grow in — wait until they are bone dry.
Will cleaning the filters fix a musty smell?
Only partly. Filters trap large dust; the musty smell usually comes from biofilm on the evaporator coil and inside the blower wheel, which homeowner cleaning can't reach. If the smell stays after a filter clean and a fan-only dry-out, book a professional deep clean.
Do I need to turn the power off to clean filters?
Yes. Turn the unit off at the remote and ideally at the wall isolator before opening the front fascia. It only takes a second and removes any risk of the fan spinning up while your hands are inside.
Can I clean the filters with a pressure washer?
No. Pressure washers deform the mesh and can push water into the housing. Lukewarm tap water and a soft brush do the job without wrecking the filter.
My filter looks fine — do I still need to clean it?
Yes. Dust builds up on the back of the mesh, the side facing the coil. A filter that looks clean from the room usually has a solid grey layer on the reverse.
Do I need to clean the outdoor unit too?
A gentle rinse of the outdoor fins with a garden hose on a low setting is fine — always with the power off at the isolator. Anything more involved is best left to a technician.
When should I replace AC filters instead of cleaning them?
Standard mesh filters last several years if rinsed gently. Replace them if you can see tears, the plastic frame is brittle, or dust passes through even after washing. Activated-carbon or HEPA-style add-on filters are usually replace-only — check your manual.
ARC Licensed – Lic. L194280