How do I know if my air conditioner has mould?

If your air conditioner smells musty, is triggering allergies, or just doesn’t feel as clean as it used to — there’s a good chance mould has started growing inside the system.

In Brisbane’s humid climate, this is extremely common. The problem is, most people don’t realise it until it’s already affecting their air quality and health.

Here’s how to tell if your air conditioner has mould — and what to do about it.

Why mould grows in air conditioners.

Air conditioners create the perfect environment for mould because:

• Moisture from condensation
• Dust and dirt buildup
• Dark internal spaces with poor airflow

If a unit isn’t cleaned properly and regularly, mould will start forming on the coil, fan barrel, and inside the drain system. Here are the most common signs your air conditioner has mould...

1. Musty or damp smell.

If you notice a stale, damp smell when the system starts up, that’s the biggest red flag.
It’s often described as a “wet sock” smell — and it doesn’t go away on its own.

2. Allergy symptoms indoors.

Mould spores get blown straight into your home. Common symptoms include:

• Sneezing or coughing
• Itchy eyes
• Headaches
• Worsened asthma

If symptoms improve when you leave the house, your air-con could be the culprit.

3. Visible black or green spots. 

• The outlet vents
• Inside the louvres
• Around the fan barrel

If you can see mould on the outside, there’s usually a lot more hidden inside.

4. Reduced airflow or performance.

Mould buildup restricts airflow and coats internal components. You might notice:

• Weak airflow
• Longer run times
• Higher power bills

It’s not just dirty — it’s costing you money.

5. Water leaks or drain issues. 

Blocked drains from sludge and biological growth can cause:

• Water dripping inside
• Overflowing drain pans
• System shutdowns

This is often tied directly to mould and bacteria buildup.

So is air conditioner mould dangerous?

Short answer: yes — especially over time.

Mould exposure can:

• Aggravate asthma and respiratory issues
• Trigger ongoing allergies
• Impact indoor air quality for your whole household

For families, kids, or anyone with breathing issues, it’s not something to ignore.

Can you clean it yourself?

Surface cleaning (like wiping filters) helps — but it doesn’t solve mould inside the unit.

Proper mould removal requires:

• Removing covers and fan barrel
• Deep cleaning the coil
• Flushing the drain system
• Using the right antimicrobial treatments

Most DIY jobs only clean what you can see — not where the problem actually is.

So how often should you service your air conditioner? 

In Brisbane conditions:

• Every 12 months minimum for normal use
• Every 6–9 months if used heavily or for households with allergies

Regular servicing prevents mould before it becomes a bigger (and more expensive) issue.

The bottom line is, if your air conditioner smells, looks dirty, or is affecting your health — it’s not something to put off.

Mould doesn’t fix itself. It only gets worse the longer it’s left.

Book a professional air conditioner clean in Brisbane.

At Blade Air Conditioning, we specialise in proper, deep cleaning of air conditioning systems — not just a quick wipe-over.

We remove mould at the source, restore airflow, and make sure your system is running cleanly and efficiently.

We service Brisbane and Bayside areas. 

Get in touch today to book a professional clean and breathe easier. Call Rick on 0427 175 073 or email us here.