5 Signs of Mould in Your Air Conditioner

Mould in your air conditioner isn’t just unpleasant − it can pose serious health risks and impact your home’s air quality.

Air conditioners provide the perfect environment for mould to thrive, thanks to moisture and dark spaces within the system. If left unchecked, mould can spread spores throughout your home, leading to respiratory issues, allergies and unpleasant odours.

The good news? Your air conditioner often gives tell-tale signs that mould may be present. Recognising these early can help you address the problem before it gets worse.

In this blog, we’ll explore the five most common signs of mould in your air conditioner and why it’s important to take action quickly. Let’s ensure your home stays fresh, clean and mould free.

1. Unpleasant Musty Odour

One of the most obvious signs of mould in your air conditioner is an unpleasant, musty odour. This distinct smell often wafts through your home as soon as you turn on the air conditioner, and it’s hard to ignore.

Mould produces this odour as it grows and releases spores into the air. If you’re noticing a smell reminiscent of damp socks or a wet basement, chances are it’s coming from your air conditioning unit.

The odour can be a result of mould growing on internal components like filters, coils or ducts. It’s not just unpleasant − it can affect your indoor air quality and potentially trigger allergies or respiratory issues.

If cleaning your filters doesn’t eliminate the smell, it’s time to call a professional heating, ventilation and air conditioning (HVAC) technician. Ignoring the problem will only allow the mould to spread, causing further damage to your system and possibly your health.

2. Visible Mould Growth on the Unit

Spotting mould on or around your air conditioner is a clear sign of trouble. Mould thrives in dark, damp environments, making your air conditioner an ideal location.

If you notice visible mould growth, it’s time to act quickly. Here’s what to look for:

• Dark spots or discolouration: Mould often appears as black, green, or brown patches on vents, filters or the unit’s exterior.
• Fuzzy or slimy texture: Check for a fuzzy coating or slimy build up, especially near the air vents or inside the unit.
• Growth in ducts or filters: Inspect removable components like filters or ducts where mould tends to collect.
• Spread to surrounding areas: Mould may extend to nearby walls, ceilings, or even furniture if left unchecked.

Cleaning visible mould with a mild detergent or specialised cleaner may help temporarily, but professional cleaning ensures it’s entirely removed and prevents regrowth.

3. Increased Allergy or Respiratory Issues

Mould in your air conditioner can have a serious impact on your health, especially if you or your family members are prone to allergies or respiratory issues.

When mould spores circulate through your home, they can trigger uncomfortable symptoms. Here’s what to watch for:

• Frequent sneezing or nasal congestion: If you’re sneezing more often or experiencing a stuffy nose, it could be mould spores in your air.
• Coughing or throat irritation: Prolonged exposure to airborne mould can lead to a persistent cough or a scratchy throat.
• Itchy or watery eyes: Mould allergens can irritate your eyes, causing redness, itching, and excessive tearing.
• Difficulty breathing or asthma flare-ups: Mould is a known trigger for asthma attacks and can worsen existing respiratory conditions.

If these symptoms seem to worsen when the air conditioner is on, it’s time to investigate for mould and address the issue promptly.

4. Poor Airflow or Reduced Efficiency

If your air conditioner isn’t cooling your home as effectively as it used to, mould could be the culprit. Mould growth inside the system can block airflow, particularly if it’s accumulated on filters, vents or coils.

When airflow is restricted, your air conditioner has to work harder to push out cool air, leading to reduced efficiency and higher energy bills.

You might notice weaker airflow from the vents, rooms taking longer to cool, or uneven cooling throughout your home. These aren’t just minor inconveniences − they’re signs that something is obstructing your system’s performance. If mould is to blame, ignoring it can cause long-term damage to your air conditioner and potentially lead to costly repairs.

Regularly cleaning your filters and scheduling routine maintenance can help prevent these issues. If you suspect mould, don’t wait − call a qualified HVAC technician to inspect and clean your system thoroughly.

5. Excess Moisture or Water Leaks Around the Unit

Excess moisture or water leaks around your air conditioner are not just inconvenient − they’re a major warning sign of mould growth.

Air conditioners naturally produce condensation, but if the drainage system isn’t functioning properly, that moisture can accumulate and create the perfect environment for mould to thrive.

You might notice water pooling near the unit, damp spots on nearby walls or ceilings, or even a consistent dripping sound. These issues often result from clogged drain lines, dirty coils, or improper installation.

If left unchecked, this excess moisture can lead to mould growth on the unit’s internal components, which then spreads harmful spores into the air.

Addressing leaks and moisture promptly is crucial. Start by checking for clogged drain lines or damaged seals. If the problem persists, it’s best to call a professional. Fixing these issues early will protect your air conditioner − and your home − from mould-related damage.

How to Address Mould in Your Air Conditioner

If you’ve spotted signs of mould in your air conditioner, it’s crucial to act quickly to prevent further growth and protect your health. Here are practical steps to address the problem:

• Turn off the unit: Stop the spread of mould spores by turning off your air conditioner until it’s cleaned.
• Clean or replace filters: Remove and clean washable filters with a mild detergent or replace them if they’re disposable.
• Inspect and clean vents: Check for mould in the air vents and clean them using a cloth and an antifungal cleaner.
• Schedule professional cleaning: For severe mould infestations, call a professional HVAC technician to thoroughly clean and disinfect the unit.
• Fix moisture issues: Address leaks, clogged drain lines, or excess condensation to prevent mould from returning.
• Invest in maintenance: Regular servicing can keep your system mould-free and running efficiently.

Acting promptly can safeguard your health, improve air quality, and extend the life of your air conditioner.

Keep Your Air Conditioner Mould Free

Mould in your air conditioner is more than a nuisance − it can affect your health, air quality, and the performance of your system.

Recognising the signs early, such as musty odours, visible mould, or increased allergy symptoms, allows you to address the issue before it worsens. Ignoring these warning signs can lead to costly repairs, reduced efficiency, and potential health risks for you and your family.

Regular maintenance, cleaning and prompt attention to leaks or poor airflow can prevent mould from taking hold in the first place. If you suspect mould in your air conditioner, don’t hesitate to act.

A professional cleaning and inspection can ensure your system is mould-free and running smoothly. By staying proactive, you can enjoy clean, fresh air and a healthy home all year round.

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.