If your split system has been blowing warm, musty air instead of the cool relief you're counting on, you're not alone. Across Australia, neglected air conditioners silently collect dust, mould, and bacteria — driving up energy bills and putting your family's health at risk. The good news? You can handle most of it yourself in under an hour.
**Quick Answer:** To clean a split system air conditioner, turn off the power, remove and wash the filters under running water, gently brush the evaporator coils with a coil cleaner, clear the drain line, and hose down the outdoor condenser unit with low-pressure water. Clean filters every 2–4 weeks during heavy use, and book a professional service once a year.
What You'll Need
Gather these before you start — most are already in your home:
Soft-bristled brush or old toothbrush
Vacuum with a brush attachment
Garden hose (no high-pressure nozzle)
Bucket of warm water with mild detergent
Microfibre cloths
**Fin comb** (around $10–$15 from Bunnings)
**Coil cleaner spray** (CRC HVAC Coil Cleaner from Bunnings, around $15)
Dust mask or P2 respirator
Gloves
**Total time:** About 45–60 minutes for a thorough clean of both units.
Safety First: Before You Start
**⚠️ Safety note:** Always turn off your air conditioner at the wall switch **and** the circuit breaker before cleaning. Water and electricity are a dangerous combination. Wait a few minutes for components to stop moving and cool down before you begin. — [energy.gov.au](https://www.energy.gov.au/households/heating-and-cooling)
A few more precautions:
**Wear a dust mask and gloves.** Mould spores can trigger asthma and respiratory infections — especially concerning for young children. [CSIRO research](https://ahd.csiro.au/eradicating-mould-would-save-millions-in-health-care-costs-how-our-homes-affect-our-health/) found that eliminating mould and damp in Australian homes could save $117 million in health costs per million people.
**Inspect the compressor tubes and pipes** for visible damage. If anything looks cracked or is leaking, stop and call a licensed technician.
**If your outdoor unit is mounted high up**, don't attempt it yourself. Leave it for a professional.
**Never open sealed refrigerant circuits.** Under Australian law, only technicians with an [ARC Refrigerant Handling Licence](https://arctick.org/) can work with refrigerant components.
How to Clean Your Split System Air Conditioner
Step 1: Clean the Filters (~10 Minutes)
This is the single most impactful task — and the easiest. Dirty filters force your AC to work harder, increasing energy use and circulating dust through your home.
Open the front panel of your indoor unit. Depending on the model, it lifts up or unclips.
Slide the filters out carefully.
Vacuum both sides to remove loose dust.
Wash under lukewarm running water with a mild detergent. [Mitsubishi Electric Australia recommends](https://www.mitsubishielectric.com.au/homeowner/support/how-to-clean-your-air-conditioner-filter/) using only diluted mild detergents — never benzene, thinners, or insecticide sprays.
Let the filters dry completely in the shade before replacing them. Never put wet filters back in.
**How often:** Every 2–4 weeks during heavy use (that's most of summer in Australia). Most Australian split systems have **washable, reusable filters** — you only need to replace them once a year, or when they show signs of wear. If your model uses disposable filters, replace every 1–3 months.
Step 2: Clean the Evaporator Coils (~10 Minutes)
With the filters removed, you'll see the evaporator coils behind them. These collect dust and can develop [mould](/cleaning-101/bathroom/a-comprehensive-guide-to-mould-removal), especially in humid climates.
Use a soft brush or vacuum with a brush attachment to gently remove surface dust.
Spray a purpose-made coil cleaner across the coils. Let it sit and drip into the drain pan — no rinsing needed.
Wipe down the drain pan with a damp cloth and mild soapy water.
**How often:** Every 6–12 months, or sooner if you notice a musty smell. If you spot visible mould, consider a professional deep clean.
Step 3: Clear the Drain Line (~5 Minutes)
A blocked drain line is the most common cause of water leaks from your indoor unit. It can also lead to mould and unpleasant odours.
Locate the drain pipe — it runs from the indoor unit to outside your home.
Check the outdoor end for blockages: algae, dirt, or insect nests.
If you have a wet-and-dry vacuum, hold it firmly over the end of the pipe for a minute to suction out debris.
**Tip:** If water is pooling around your indoor unit, it could mean a clogged drain line, a cracked drain pan, or a frozen evaporator coil. Check the drain first — if the problem persists, call a technician.
Step 4: Clean the Outdoor Condenser Unit (~15 Minutes)
The outdoor unit pulls air across its fins to release heat, so it collects leaves, dust, cobwebs, and other debris over time.
Remove the outer panels or grille (usually held by screws) and set them aside.
Vacuum or brush away loose debris from around the fan and fins.
Using a garden hose with **gentle, low pressure**, spray from the inside out to push dirt through the fins. **Never use a pressure washer** — condenser fins are thin aluminium, and high pressure will bend or crush them permanently.
If you find bent fins, straighten them carefully with a **fin comb** (available at Bunnings for $10–$15). This purpose-built tool matches your fin spacing and won't scratch. A flat-head screwdriver works in a pinch for individual fins, but avoid knives or other improvised tools.
Wipe down the fan blades with a damp cloth.
Dust the electrical compartment gently with a dry feather duster or soft paintbrush. Avoid pulling or loosening any wires.
Hose down the removable panels, wipe dry, and screw everything back together.
**⚠️ Safety note:** Keep at least 60 cm of clearance around your outdoor unit on all sides — 1 metre is ideal for optimal airflow. Trim back plants, remove bird nests, and clear any debris. — [CHOICE Australia](https://www.choice.com.au/home-and-living/cooling/air-conditioners/articles/how-to-clean-your-air-conditioner)
**Important:** After cleaning, wait at least 30 minutes for all components to dry before switching the power back on. Then run the AC for 15–20 minutes and check for unusual noises or smells.
The Mould Prevention Trick Most People Miss
You might have tried cleaning your filters regularly, only to wonder why your split system still smells musty weeks later. The culprit is usually moisture sitting inside the unit after it switches off.
Here's what works: **after running your AC in cooling mode, switch it to fan-only mode for 15–20 minutes before turning it off completely.** This dries out the evaporator coils and drain pan, removing the moisture that mould needs to thrive.
Some newer models (Daikin, Mitsubishi, Fujitsu) have an auto-dry function that does this automatically — check your remote for a "dry" or "internal clean" setting.
In humid parts of Australia — Brisbane, the Gold Coast, Sydney's coastal suburbs — this one habit can dramatically reduce mould buildup between cleans.
Maintenance Habits That Save You Money
A well-maintained split system doesn't just cool better — it costs less to run. According to the [Australian Government's energy.gov.au](https://www.energy.gov.au/households/heating-and-cooling), each degree of extra cooling increases energy consumption by 5–10%.
Simple habits that make a real difference:
**Set your thermostat to 25–27°C in summer.** Comfortable for most people, and noticeably cheaper to run.
**Raise the temperature when you leave.** Bump it up 4–5 degrees when you're out. Your AC won't struggle to catch up when you return.
**Inspect your ductwork** if you have a ducted system. Leaky ducts waste energy. Seal gaps with HVAC tape or duct sealant (both available at Bunnings).
**Keep a simple schedule.** Filters every 2–4 weeks. Coils and outdoor unit every 6–12 months. Professional service once a year. If you're already [managing a clean home on a busy schedule](/cleaning-101/uncategorized/how-to-keep-your-home-clean-with-a-busy-schedule), this fits right into your seasonal routine.
When to Call a Professional
DIY cleaning covers the basics, but some tasks need a licensed HVAC technician:
**Annual professional service.** [Fujitsu General Australia recommends](https://www.fujitsugeneral.com.au/help-centre/helpful-articles/details/how-often-to-service-an-air-conditioner) at least one professional service per year. Expect to pay **$100–$200 per unit** in most Australian cities.
**Persistent musty smells** after you've cleaned the filters and coils.
**Water leaks** that don't resolve after clearing the drain line.
**Unusual noises** — rattling, grinding, or clicking.
**Reduced cooling performance** despite clean filters and clear airflow.
**Any work involving refrigerant** — this requires an ARC-licensed technician by law.
A yearly professional service catches small problems before they become expensive repairs. It's a worthwhile investment, not an expense.
Frequently Asked Questions
Q: How often should you clean a split system air conditioner?
Clean filters every 2–4 weeks during heavy use (summer and winter). Clean evaporator coils and the outdoor condenser unit every 6–12 months. Schedule a professional service at least once a year.
Q: Why does my split system smell musty even after I've cleaned the filters?
The smell usually comes from mould on the evaporator coils or in the drain pan — not the filters themselves. Clean the coils with a purpose-made coil cleaner, and run your AC in fan-only mode for 15–20 minutes after each cooling session to prevent moisture buildup.
Q: Can I clean my air conditioner coils with vinegar?
Vinegar can help clean the drain pan, but it's not recommended for evaporator or condenser coils. Coil-specific cleaners (available at Bunnings for around $15) are formulated to clean without damaging the aluminium. Avoid abrasive or highly acidic cleaners on coils.
Q: Is it worth getting a professional AC clean, or can I do it myself?
For regular maintenance — filters, basic coil brushing, clearing the outdoor unit — DIY is perfectly fine. But a professional deep clean reaches components you can't easily access, like behind the barrel fan and inside the drain channel. If your system is older than three years and hasn't been professionally cleaned, it's worth the $100–$200 investment.
Q: What happens if I don't clean my air conditioner?
Dust and mould accumulate, reducing cooling efficiency and air quality. Your unit works harder, increasing energy bills. Mould spores circulating through your home can trigger allergies and respiratory issues — especially concerning for young children and anyone with asthma.
Related Reading
[A Systematic Way to Clean Your Kitchen](/cleaning-101/kitchen/a-systematic-way-to-clean-your-kitchen)
[A Comprehensive Guide to Mould Removal](/cleaning-101/bathroom/a-comprehensive-guide-to-mould-removal)
[How to Keep Your Home Clean With a Busy Schedule](/cleaning-101/uncategorized/how-to-keep-your-home-clean-with-a-busy-schedule)
[Green Cleaning 101: How to Make and Use Natural Cleaning Solutions](/cleaning-101/sustainability/green-cleaning-101-how-to-make-use-natural-cleaning-solutions)
[A Cleaning Guide to Sparkling Stainless Steel Appliances](/cleaning-101/kitchen/a-cleaning-guide-to-sparkling-stainless-steel-appliances)
Sources & References
**Australian Government, Department of Climate Change, Energy, the Environment and Water** — [Heating and Cooling](https://www.energy.gov.au/households/heating-and-cooling). Referenced for energy consumption impact of thermostat settings (5–10% per degree).
**CSIRO, Australian Housing Data** — [Eradicating Mould Would Save Millions in Health Care Costs](https://ahd.csiro.au/eradicating-mould-would-save-millions-in-health-care-costs-how-our-homes-affect-our-health/). Referenced for mould-related health expenditure in Australian homes.
**Mitsubishi Electric Australia** — [How to Clean Your Air Conditioner Filter](https://www.mitsubishielectric.com.au/homeowner/support/how-to-clean-your-air-conditioner-filter/). Referenced for filter cleaning frequency and safe cleaning product guidance.
**Fujitsu General Australia** — [How Often to Service an Air Conditioner](https://www.fujitsugeneral.com.au/help-centre/helpful-articles/details/how-often-to-service-an-air-conditioner). Referenced for professional servicing frequency recommendation.
**CHOICE Australia** — [How to Clean Your Air Conditioner](https://www.choice.com.au/home-and-living/cooling/air-conditioners/articles/how-to-clean-your-air-conditioner). Referenced for condenser clearance requirements and energy-saving tips.
**Australian Refrigeration Council (ARC)** — [Refrigerant Handling Licence](https://arctick.org/). Referenced for legal requirements around refrigerant work in Australia.
*If keeping on top of home maintenance feels like one thing too many, our friendly team is always here to help.*
*Care for your home. Respect for the people behind every clean.*