10 Common Problems with Ducted Air Conditioning

Noticing reduced airflow, strange smells, or temperature inconsistencies in your home or workplace? These could be signs that your ducted air conditioning system needs attention. While ducted systems are designed for long-term comfort and quiet operation, like any major appliance, they can develop faults over time. Recognising early warning signs can help avoid larger issues and extend the life of your system. In this blog, we’ll explore 10 common air conditioning issues and why professional servicing is essential to keep your ducted air conditioning running smoothly.

1. Inconsistent Temperature Across Zones

A common complaint with ducted air conditioning is uneven temperatures between rooms. You may find one area too cold while another remains warm, even with zoning enabled. This often results from blocked vents, faulty dampers, or issues with the zoning control system.

When left unresolved, inconsistent temperatures can strain your system and reduce overall efficiency.

2. Reduced Airflow from Vents

If your vents are producing weak or limited airflow, the problem could lie in the ductwork. Collapsed ducts, dislodged joints, or blockages from dust buildup can restrict air distribution.

Low airflow also forces your system to work harder, increasing energy use and reducing comfort levels—especially during peak summer and winter periods.

3. Unusual Noises from the System

Ducted systems are known for their quiet performance, so if you notice rattling, whirring, or banging noises, it’s worth investigating. These sounds could indicate a loose fan blade, worn motor bearings, or something as simple as a displaced duct panel.

Ongoing noise often signals a mechanical issue that could worsen without timely repair.

4. Bad Odours from Air Vents

Foul smells from the air vents can point to mould or mildew inside the ductwork. Moisture build-up, combined with dust, creates an ideal environment for microbial growth.

Not only is this unpleasant, but it can also affect indoor air quality. Regular servicing and duct cleaning can help prevent this common air conditioning issue.

5. Thermostat Not Responding

When your thermostat becomes unresponsive or displays incorrect readings, it can affect the entire system’s performance. You might notice the air conditioning not turning on, staying on too long, or failing to reach the set temperature.

Faulty wiring, sensor problems, or outdated components may be the cause. A professional inspection can determine whether recalibration or replacement is needed.

6. Water Leaks Around the Unit

While condensation is a normal part of air conditioning operation, excessive water around the indoor unit or drainage system is not. Blocked drain lines or cracked drip trays are often responsible for leaks.

Left unattended, these leaks can damage ceilings, walls, or electrical components, creating a safety hazard and repair expense.

7. System Not Turning On

If your ducted air conditioning system doesn’t switch on at all, there may be an electrical issue, a blown fuse, or a problem with the circuit board. Alternatively, a faulty thermostat or remote may be to blame.

This issue typically requires diagnosis by a qualified technician to avoid damage to internal components.

8. Poor Energy Efficiency

If you’ve noticed a sudden spike in your electricity bills, your air conditioning system may be using more energy than necessary. Dirty filters, leaky ducts, or an overworked compressor can all reduce efficiency.

Regular servicing and airflow testing can help identify the cause and restore energy-efficient operation—an important step for both residential and commercial premises.

9. System Frequently Short Cycling

Short cycling occurs when the system turns on and off repeatedly without completing a full cycle. This can result in poor temperature control, increased wear on components, and higher power consumption.

Common causes include oversized systems, clogged filters, or low refrigerant levels. Identifying and addressing this issue early can extend system lifespan and improve comfort.

10. Ageing System Components

As ducted air conditioning systems age, components such as fans, motors, valves, and control boards can degrade or fail. An older system may also rely on outdated refrigerants that are no longer compliant with current standards.

If your system is over 10–15 years old and showing multiple faults, it may be more cost-effective to discuss an upgrade rather than continued repairs.

Why Professional Servicing Matters

Even when issues appear minor, regular inspections by qualified technicians are essential for diagnosing underlying problems. Servicing can involve:

• Checking airflow, refrigerant levels, and electrical connections.
• Cleaning filters, coils, and condensate drains.
• Testing zone control and thermostat responsiveness.
• Identifying worn or damaged components before failure.

Whether you're a homeowner or manage a commercial property, ongoing maintenance can reduce the risk of system breakdowns and help manage energy costs more effectively.

Preventative Maintenance Tips

In between professional servicing, there are a few things you can do to maintain your ducted air conditioning system:

• Clean return air filters regularly: Dirty filters block airflow and reduce efficiency.
• Keep outdoor units clear: Remove leaves, branches, and obstructions from around external units.
• Monitor performance: Be alert to any changes in temperature, airflow, or system sounds.
• Use zoning wisely: Only cool or heat the rooms in use to reduce system load.
• Book annual servicing: A yearly inspection helps catch problems early, before they lead to costly repairs.

Taking these steps can support long-term performance and protect your investment.

When to Call a Professional

If you notice persistent or sudden issues with your ducted air conditioning—such as water leaks, unusual smells, or lack of temperature control—it’s important to contact a licensed technician. DIY repairs can lead to safety risks, void warranties, or make problems worse.

Professional servicing not only resolves immediate concerns but can also provide guidance on whether your system is functioning at its full potential. This can be especially helpful for businesses looking to maintain consistent comfort for staff and customers.

Book a Ducted Air Conditioning Service Today!

Ducted air conditioning offers whole-home comfort, but like any system, it requires routine care and attention. From blocked ducts and faulty thermostats to ageing components and short cycling, recognising common air conditioning issues early can help avoid major disruptions. A proactive approach to maintenance ensures your system performs reliably throughout the year.

At Marty Nelson Refrigeration & Air Conditioning, we provide expert servicing for ducted air conditioning systems, helping local homes and businesses stay comfortable and energy-efficient. Contact us today to book your inspection or service and keep your system running at its best.