Why Your Air Conditioner Grows Mould And How EvidiAir Fixes It for Good
- Brett Wells
- Dec 6
- 3 min read
We’ve all experienced that moment: you switch on the AC expecting cool, clean air and instead get hit with a musty, damp smell. On the Gold Coast, where humidity is high, summers are long and the air is often salty, mould in air conditioners is one of the most common and most dangerous problems homeowners face. Left untreated, mould damages your system, increases energy bills and puts your family’s health at risk.
At EvidiAir, we specialise in professional hydro cleaning that removes mould deep within your unit, restores healthy airflow and keeps your home safe and comfortable.
Why Does Mould Grow Inside Air Conditioners?
Humidity, the main trigger
Humidity is the number one reason ACs develop mould on the Gold Coast. Moisture collects on the evaporator coil, drain pan and inside ductwork. When the system can’t dry out properly, these areas stay damp, creating the perfect breeding ground for mould spores. A single humid week can be enough for mould to begin forming inside your unit, especially in older systems.
Dust, grime and biofilm
Dust mixed with moisture forms a thick, sticky layer known as biofilm. This biofilm coats coils, fans and internal casing, trapping bacteria and organic particles. Once this layer forms, it becomes extremely difficult to remove without professional equipment. Every time the AC runs, it blows microscopic spores and musty odours into your living space.
Clogged drains and poor airflow
A blocked condensate drain is one of the biggest contributors to internal mould. When the drain line fills with slime or debris, water pools inside the unit instead of escaping. Stagnant water becomes a mould hotspot. Poor airflow, often caused by dirty filters or obstructed intake vents, keeps internal parts wet for longer, speeding up fungal growth.
Irregular maintenance
Mould grows quietly and slowly and you often won’t notice it until the smell becomes strong. If filters aren’t replaced and the system isn’t serviced, the contamination spreads into the blower barrel, internal casing and even the ductwork. By the time most homeowners detect it, the mould problem is no longer small.
The Health & Performance Impacts of AC Mould
Health consequences
Mould spores circulating indoors can trigger respiratory irritation, coughing, wheezing, itchy eyes and allergy symptoms. Children, infants, the elderly and those with asthma or immune issues are especially vulnerable. Long-term exposure can worsen existing conditions and lower your home’s overall air quality, something many families never connect back to their air conditioner.
Smells, comfort and nuisance
That unmistakable “dirty sock smell” or damp, earthy odour is almost always caused by mould on coils, inside the drain pan or within the ducts. These smells travel through every room the moment the unit switches on. Even if your home looks clean, the odour can make rooms feel stale and uncomfortable.
System strain and costs
Mould acts like insulation where it shouldn’t, coating the coil and blocking heat transfer. The system has to work much harder to cool your home, which leads to:
Higher electricity bills
Longer cooling cycles
Faster wear and tear
Reduced system lifespan
Small mould problems can quickly become costly repairs if ignored.
How EvidiAir’s Hydro Clean Removes Mould for Good
Wipes, sprays and DIY cleaning won’t reach the hidden contamination deep inside your unit. EvidiAir’s Hydro Clean is a specialised, high-pressure cleaning process designed to eliminate mould at the source. It includes:
High-pressure coil washing to strip away biofilm, grime and fungal growth.
Fan and blower barrel deep cleaning to remove trapped spores.
Drain-line flushing and sanitisation to stop recurring blockages.
Casing, louvers and accessible duct sanitisation to remove odours permanently.
Antibacterial treatment to help prevent mould regrowth.
After a hydro clean, your unit runs cooler, smells fresh and operates far more efficiently, often reducing your power bill straight away.
Quick Home Tips to Reduce Mould Risk
Replace or clean AC filters every 1–3 months.
Run the AC fan after cooling cycles to help dry moisture.
Use a dehumidifier during extremely humid weeks.
Keep outdoor condensers shaded and free from debris.
Schedule professional hydro cleaning every 6–12 months.
These small habits keep mould from returning and extend your system’s lifespan.
Book an EvidiAir Hydro Clean Today
Don’t let mould damage your AC or impact your family’s health. EvidiAir offers expert hydro cleaning and professional servicing across the Gold Coast to remove mould thoroughly and restore healthy air circulation.
📍Serving Helensvale, Arundel, Hollywell, Pimpama and all Gold Coast suburbs
