Aircon Mould Brisbane

Why Air Conditioners Get Mouldy

Your air conditioning system is designed to cool air by removing heat — and in the process, it also removes moisture. This moisture collects on the evaporator coil and drains away through a condensate line. Under normal operation, this is perfectly fine.

The problem in Brisbane’s climate is that the combination of high humidity, warm temperatures, and the moist internal environment of the air conditioning unit creates ideal conditions for mould growth. When the unit cycles off, moisture remains on the coil and in the drain pan, and with Brisbane’s ambient warmth, mould can colonise these damp surfaces quickly.

Signs of Mould in Your Air Conditioner

• Musty smell when the unit runs — the most common indicator. If turning on your air conditioner produces a stale, musty, or earthy odour, mould is likely growing inside the unit
• Visible mould on vents — dark spots or fuzzy growth on or around the supply air vents
• Black spots on louvres — mould growth on the directional louvres of split system indoor units
• Health symptoms when aircon runs — sneezing, coughing, watery eyes, or headaches that start when the air conditioner is on and improve when it’s off
• Increased allergy symptoms — air conditioning that circulates mould spores can aggravate allergies and asthma

Where Mould Grows Inside Air Conditioning Systems

• Evaporator coil — the cold, damp surface where air is cooled is the primary mould location
• Drain pan and condensate line — standing water in the drain pan or a partially blocked drain line provides a constant moisture source
• Air filters — dirty or clogged filters trap moisture and organic particles that feed mould growth
• Blower fan (barrel fan) — the cylindrical fan that pushes air through the unit accumulates dust and moisture
• Supply ducts — in ducted systems, condensation inside ductwork can support mould growth, particularly in uninsulated or poorly insulated sections
• Vent grilles — where cold conditioned air meets warmer room air, condensation can form on vent surfaces

Health Risks of Aircon Mould

Air conditioning mould is particularly concerning because the unit actively distributes spores throughout the space it serves. Every time the system runs, it can push mould spores into the air you breathe. This can contribute to:

• Respiratory irritation and persistent coughing
• Aggravation of asthma symptoms
• Allergic reactions — sneezing, congestion, itchy eyes
• Headaches and fatigue
• In rare cases, more serious respiratory infections in vulnerable individuals

Because the mould is often hidden inside the unit rather than visible on surfaces, many people experience symptoms without connecting them to their air conditioner.

Professional Aircon Mould Cleaning

Cleaning mould from an air conditioning system requires more than wiping down the filters. Professional aircon mould cleaning typically involves:

1. Disassembly — the indoor unit is partially disassembled to access the evaporator coil, barrel fan, and drain pan
2. Coil cleaning — the evaporator coil is cleaned with specialist coil cleaning solutions that remove mould, dust, and biofilm
3. Barrel fan cleaning — the blower fan is thoroughly cleaned to remove accumulated mould and debris
4. Drain line flushing — the condensate drain is flushed to clear any blockages and mould buildup
5. Antimicrobial treatment — surfaces are treated with antimicrobial solutions to inhibit future mould growth
6. Filter replacement — old filters are replaced with clean ones
7. Reassembly and testing — the unit is reassembled and tested to confirm proper operation and clean air output

DIY vs Professional Cleaning

Some basic maintenance can be done yourself:

• Filters — clean or replace filters every 2-4 weeks during heavy-use periods (Brisbane’s summer)
• Visible vent surfaces — wipe down louvres and vent grilles with a damp cloth

However, cleaning the internal components — coils, barrel fan, drain pan — requires disassembly and specialist knowledge. Incorrect handling can damage the unit, void warranties, or spread mould contamination rather than removing it.

Preventing Aircon Mould

• Run “dry” mode after cooling — many modern units have a dry or fan-only mode. Running this for 15-30 minutes after cooling dries moisture from the coil and reduces mould risk
• Clean filters regularly — dirty filters restrict airflow and increase moisture accumulation on the coil
• Schedule annual professional servicing — a yearly clean and service keeps mould from building up
• Don’t set the temperature too low — extreme temperature differences between conditioned and ambient air increase condensation throughout the system
• Keep the area around the outdoor unit clear — good airflow around the external unit helps the system operate efficiently
• Address other moisture issues — if the home has broader humidity or condensation problems, the air conditioner works harder and accumulates more moisture

Aircon Mould and Whole-Home Mould Problems

Sometimes, aircon mould is a symptom of a broader moisture issue in the home. If your air conditioner develops mould quickly after cleaning, or if mould is appearing on walls and ceilings as well, the home’s overall moisture levels may need addressing. A professional mould inspection can assess whether the aircon mould is an isolated issue or part of a larger problem.

Get Your Aircon Assessed

If your air conditioner smells musty or you’re experiencing symptoms when it runs, connect with a specialist who can inspect and clean your system properly. For broader mould issues in your home, our network of Brisbane mould removal specialists can assess and address the full scope of the problem.