Why Your Aircon Smells: How to Breathe Clean Air Again at Home

Have you ever turned on your air conditioner only to be hit with a foul smell? Whether it’s musty, mouldy or just plain unpleasant, a smelly aircon can ruin the comfort of your home.

Worse, it could be a sign of deeper issues like mould growth, clogged filters, or even electrical problems. Ignoring these odours isn’t just unpleasant − it can also impact your health and indoor air quality.

Luckily, you don’t have to live with bad smells coming from your AC. Understanding the cause is the first step to fresh, clean air. In this guide, we’ll explore why your aircon smells, how to get rid of the odours, and simple maintenance tips to keep your home smelling fresh.

Let’s get your aircon back to delivering cool, clean air.

Common Reasons Your Aircon Smells Bad

If your air conditioner is giving off a bad smell, there’s usually an underlying issue that needs attention. Here are some of the most common causes:

• Mould and mildew growth – Moisture inside your aircon can create the perfect environment for mould and mildew. This often leads to a musty or damp smell, especially if the filter or drain pan is dirty.
• Clogged or dirty air filters – Dust, pet hair and bacteria can build up on filters over time. A dirty filter not only reduces air quality but can also produce a stale, unpleasant odour.
• Burning smell – A strong burning odour could mean electrical issues, overheating components, or dust burning off after long periods of inactivity. If the smell persists, turn off your AC and call a technician.
• Rotten egg smell – If you detect a sulfur-like odour, it may indicate a gas leak nearby. This is a serious issue and requires immediate professional attention.
• Dead animal smell – Occasionally, small pests can get trapped inside ducts, causing an awful odour as they decompose.

Regular maintenance can help prevent these smells and keep your air fresh.

Odours in Different Types of Air Conditioners

No matter what type of air conditioner you have, bad smells can develop over time. Each system has unique reasons why odours might occur, and knowing what to look for can help you fix the problem faster.

Split system air conditioners often develop musty or mouldy smells due to moisture buildup in the indoor unit. If the filters or drain lines are clogged, bacteria and mould can thrive, causing unpleasant odours.

Ducted air conditioners can spread bad smells throughout your home if mould or dust accumulates in the ducts. A dead rodent or pest inside the ductwork can also create a foul, lingering odour.

Window air conditioners are more prone to musty smells because they’re exposed to outdoor humidity and rain. A clogged filter or dirty evaporator coil can also contribute to unpleasant scents.

Portable air conditioners can develop a damp smell if the water tank isn’t emptied regularly. Stale air from a dirty filter can also cause an unpleasant odour.

Regular cleaning and maintenance will help keep any type of aircon smelling fresh and working efficiently.

How to Get Rid of Aircon Odours

If your air conditioner is producing unpleasant smells, don’t worry − you can take steps to eliminate the odours and restore fresh, clean air.

Here’s what you can do:

• Clean or replace air filters – Dirty filters trap dust, bacteria, and mould, which can cause bad smells. Regularly cleaning or replacing filters will help maintain fresh air.
• Check and clean the drain pan and drain line – Excess moisture can lead to mould growth. Empty and clean the drain pan, and flush the drain line with a mixture of water and vinegar to prevent clogs.
• Wipe down the evaporator coils – Dust and bacteria can accumulate on coils, creating a musty smell. Use a soft brush or coil cleaner to keep them fresh.
• Use an aircon disinfectant spray – These sprays help kill bacteria and neutralise odours inside the unit.
• Schedule a professional cleaning – If the smell persists, a deep clean by an HVAC technician can remove hidden mould, pests and built-up grime.

By following these steps, your aircon will stay fresh and odour-free.

Preventive Maintenance Tips for Fresh Air

Keeping your air conditioner clean and well-maintained is the best way to prevent unpleasant odours. Here are some simple maintenance tips to ensure your AC continues to deliver fresh, clean air:

• Clean or replace air filters regularly – Dirty filters trap dust, mould and bacteria, leading to bad smells. Check your filter every month and replace it as needed.
• Keep the drain line and drain pan clean – A clogged drain line can cause water to stagnate, leading to musty odours. Flush the drain line with a mix of vinegar and water to keep it clear.
• Schedule annual professional servicing – A technician can deep-clean your system (including duct cleaning if you have a ducted system), inspect for mould and ensure all components are working properly.
• Control humidity levels indoors – Excess humidity encourages mould growth inside your AC. Use a dehumidifier if needed to maintain balanced moisture levels.
• Use an air purifier – This helps remove airborne particles, reducing dust and bacteria that can contribute to odours.

With regular care, your aircon will stay fresh, efficient and odour-free year-round.

Don’t Put Up with Bad Smells

A smelly air conditioner isn’t just unpleasant − it can be a sign of dust buildup, mould growth, or even more serious issues like electrical problems. Luckily, you don’t have to put up with bad odours. By identifying the cause and taking the right steps, you can keep your aircon smelling fresh and working efficiently.

Regular maintenance, such as cleaning or replacing air filters, flushing the drain line, and scheduling professional servicing, can prevent odours before they start. Keeping humidity levels in check and using air purifiers can also improve your indoor air quality.

If your aircon still smells despite cleaning, it may be time to call in an expert. A professional can inspect, deep-clean, and fix any hidden problems. Take action today and enjoy cool, clean air again.

Please note: This information is provided for advice purposes only. Regulations differ from state to state, so please consult your local authorities or an industry professional before proceeding with any work. See our Terms & Conditions here.