If your aircon has been blowing warm air lately, making strange smells, or your power bill has quietly crept up — don’t rush to call a technician just yet. Nine times out of ten, the culprit is a dirty aircon coil.
Here in Perth, our summers are brutal. We’re talking 40°C-plus days that stretch for weeks. Your aircon is basically running non-stop from November through to March, pulling in dust, pollen, and all that dry Perth air — and it all ends up caked on your coils. The result? Your unit works twice as hard to cool half as well.
The good news is that cleaning your aircon coil isn’t as complicated as it sounds. With the right steps and a bit of time on a weekend morning, you can do it yourself and genuinely feel the difference within hours.
Let’s get into it.
What Is an Aircon Coil and Why Does It Get So Dirty?
Before you start, it helps to understand what you’re actually dealing with.
Your air conditioner has two types of coils — the evaporator coil (inside your home, part of the indoor unit) and the condenser coil (in the outdoor unit).
Both play a critical role in the heat exchange process that cools your home.
The evaporator coil absorbs heat from the air inside your room. The condenser coil releases that heat outside. When either one gets caked in dust, grime, or mould, the heat transfer becomes inefficient — and that’s when the problems start.
In Perth specifically, the combination of dry, dusty conditions and high pollen counts during spring and summer means coils build up gunk faster than in cooler, wetter cities. Homes in areas like Ellenbrook, Baldivis, and the eastern suburbs are particularly prone to heavy dust buildup due to the surrounding bushland and unsealed roads.
A dirty coil doesn’t just mean poor cooling. It also means:
- Higher electricity bills (your unit runs longer to reach the set temperature)
- Musty or stale smells coming from your vents
- More wear and tear on the compressor
- A shorter lifespan for your whole system
- Potential mould growth inside the unit
Signs Your Aircon Coil Needs Cleaning Right Now
You don’t need to be a technician to recognise when something’s off. Watch for these warning signs:
- Your aircon isn’t cooling properly.
- If it used to cool your room in 10 minutes and now it takes 30, dirty coils are often the reason.
- Ice is forming on the coil or copper pipes.
- This is a classic symptom of a blocked evaporator coil. Restricted airflow causes the refrigerant to get too cold and freeze over.
- The unit smells bad.
- Mould and mildew love dark, damp coil fins. If you’re getting a musty whiff every time you turn the aircon on, it’s time for a proper clean.
- Your power bill has gone up for no obvious reason.
- A dirty coil makes your compressor work harder and longer. That shows up on your bill fast — especially in a Perth summer when the unit’s running all day.
- Water is leaking from the indoor unit.
- A frozen evaporator coil melts and overflows the drain pan. Again — dirty coil.
What You’ll Need Before You Start
Grab these before you begin. Most of this you can find at Bunnings or any hardware store across Perth:
- A soft-bristle brush or old toothbrush
- A can of no-rinse foaming coil cleaner (or a DIY mix of warm water and mild dish soap)
- A fin comb (optional but helpful if your fins are bent)
- A spray bottle
- Clean dry cloths or microfibre towels
- A vacuum cleaner with a brush attachment
- Protective gloves and safety glasses
If you want a proper deep clean, a purpose-made aircon coil cleaner spray does a better job than soap and water. You’ll find these at most air conditioning supply stores around Perth, or online.
How to Clean Aircon Coils — Step by Step
Step 1: Turn Everything Off at the Power
Safety first — always. Switch your aircon off at the unit, then turn it off at the wall switch or circuit breaker. Don’t just use the remote. You want zero power going to the unit while you’re working on it.
Step 2: Remove and Clean the Air Filter
Before you touch the coil, take out the air filter. In most split system units, this slides out from behind the front panel. Hold it over a bin and give it a tap to knock off the loose dust, then rinse it under warm water. Let it dry completely before putting it back — never reinstall a wet filter.
If the filter is torn or falling apart, replace it. A clean filter is your first line of defence against a dirty coil.
Step 3: Access the Evaporator Coil
Open the front panel of your indoor unit carefully. You’ll see the evaporator coil — it looks like a series of thin metal fins arranged in a curved row. Don’t bend them, they’re fragile.
Use your vacuum with the brush attachment to gently remove loose dust from the surface of the fins. Work from top to bottom in slow, light strokes. Don’t press too hard or you’ll bend the fins and restrict airflow.
Step 4: Apply the Coil Cleaner
Shake your foaming coil cleaner well, then spray it evenly across the evaporator coil fins. Most no-rinse cleaners are designed to foam up, break down the grime, and then drip down into the drain pan — taking the dirt with them. Follow the directions on the can, but usually you let it sit for 5 to 10 minutes.
If you’re using a soap-and-water mix in a spray bottle, apply it generously and let it soak in for a few minutes. Then use your soft brush to gently scrub the fins in an up-and-down motion, following the direction of the fins. Never scrub side to side — you’ll bend them.
Step 5: Rinse (If Required) and Wipe Down
If your cleaner requires rinsing, use a low-pressure spray of clean water. Avoid high-pressure anything — the fins are delicate. Wipe down the surrounding casing with a damp cloth.
Check the drain pan at the bottom of the unit. If there’s standing water, slime, or mould in there, clean it out with your cloth and a mild disinfectant. A blocked drain pan is a common cause of water leaks.
Step 6: Clean the Outdoor Condenser Coil
Head outside to your outdoor unit. This one cops the worst of Perth’s dust and heat.
Turn off the power at the isolator switch on the wall near the unit. Remove the outer casing (usually a few screws) to access the condenser coil. Use your vacuum to remove debris — leaves, dust, spiderwebs, seeds from nearby gum trees are all common culprits here.
Spray the condenser coil cleaner from the inside out if possible, pushing the dirt out through the fins rather than deeper into them. Rinse with a gentle hose spray. Let it dry before replacing the casing.
Step 7: Reinstall Everything and Test
Put the filter back in once it’s fully dry. Close all panels. Restore power at the circuit breaker. Turn the unit on and let it run for 10 to 15 minutes.
Notice the difference? Most Perth homeowners notice stronger airflow, cooler air, and often a fresher smell almost immediately after a proper coil clean.
DIY Cleaning vs Professional Aircon Servicing — Which One Do You Need?
DIY coil cleaning is great for regular maintenance — and doing it every 3 to 6 months keeps your system running efficiently year-round.
But there are times when you genuinely need a professional. Consider booking an aircon technician in Perth if:
- Your unit still isn’t cooling properly after a thorough DIY clean
- You can see visible mould deep inside the unit that you can’t reach
- There’s a refrigerant leak (you’ll notice ice forming and a hissing sound)
- It’s been more than 12 months since your last professional service
- You want a full aircon chemical wash — a deep clean that strips the coil, blower wheel, and casing with professional-grade solution
A chemical overhaul from a Perth aircon technician typically costs on the unit size and how dirty it is. It’s worth every dollar once a year, especially if you’re running the system hard through summer.
How Often Should You Clean Your Aircon Coils in Perth?
Given Perth’s climate and dust levels, here’s a sensible maintenance schedule:
- Every 4 to 6 weeks — Clean or check the air filter
- Every 3 months — DIY clean of the indoor evaporator coil during heavy-use months
- Every 6 months — Clean the outdoor condenser coil
- Once a year — Full professional service including chemical wash, drain check, and refrigerant test
Stick to this routine and you’ll avoid most of the expensive breakdowns that hit Perth homeowners every summer when they’ve neglected their units all winter.
Quick Tips to Keep Your Coils Cleaner for Longer
A few simple habits go a long way:
- Keep doors and windows closed when the aircon is running — less dust enters the room
- Trim any plants or shrubs near the outdoor unit to maintain good airflow
- Don’t run the unit on very dusty days without checking the filter more frequently
- Use the “auto” fan mode rather than constant fan — it reduces the amount of unfiltered air passing through the system
Frequently Asked Questions About Aircon Coil cleaning
1. How often should I clean my aircon coil in Perth?
Every 3 months for the indoor coil during summer, and every 6 months for the outdoor condenser coil. Perth’s dusty climate means more frequent maintenance than most other Australian cities.
2. Can I clean my aircon coil myself?
Yes, absolutely. With a coil cleaner spray, a soft brush, and basic safety precautions, most homeowners in Perth can do a solid DIY clean without any special skills.
3. What is an aircon chemical wash?
It’s a professional deep-cleaning process where a licensed technician dismantles the indoor unit and soaks the coil, blower wheel, and casing in a chemical solution to remove mould, bacteria, and heavy grime buildup. It’s recommended once a year for heavily used systems.
4. Why is my aircon coil freezing over?
A frozen evaporator coil is almost always caused by restricted airflow — usually a clogged filter or dirty coil. Clean both and let the unit thaw completely before restarting it.
5. Will cleaning the coil really lower my power bill?
Yes. A clean coil transfers heat more efficiently, so the compressor runs for shorter cycles. Many Perth homeowners notice a measurable drop in their electricity bill after a thorough clean.
Conclusion
A dirty aircon coil is one of those problems that sneaks up on you. It doesn’t fail dramatically — it just quietly makes your system less efficient, more expensive to run, and eventually leads to a breakdown at the worst possible time (usually on the hottest day in January when every technician in Perth is booked solid).
Cleaning your aircon coils is one of the easiest and most effective things you can do to extend the life of your unit, lower your bills, and keep your home genuinely comfortable through a Perth summer.
Do it yourself every few months. Get a professional in once a year. Your aircon — and your wallet — will thank you.