Rule out the controller
Make sure the zone is turned on and that no schedule or app setting is closing it. With temperature-controlled zones, each zone's damper closes as that zone reaches its set temperature, so a quiet zone may simply be satisfied. Raise or lower its set point and listen for a change at the outlets. If each zone has its own sensor, check it isn't sitting in sunlight, above a heater or next to an outlet.
If the controller shows a fault for that zone, or the zone won't respond at all, note what it says. A controller that was reset by a power outage may need its zones set up again.
Damper motors and cables
Each zone has a damper in the duct, opened and closed by a small motor. Those motors live in a roof space that swings from near freezing on July nights to baking in January, and they wear out. A failed motor can leave the damper stuck closed, so the zone gets nothing, or stuck open, so it can't be turned off. The cable to the motor can also be crushed or pulled loose by anyone working in the roof.
A disconnected or crushed duct
If the system is running and other zones work, but one or two outlets get little or no air, a duct may have come off its outlet or junction, or been flattened. The air ends up in the roof space instead of the room. Signs include a roof space that feels unusually hot or cold, a rushing sound near the manhole, or a jump in running costs. Ducts and damper motors are reached from the roof, so leave that to a technician.
What you can safely do now
- Check the zone is on, and look for schedules or app settings closing it.
- Change the zone's set temperature and listen for air at its outlets.
- Check the other outlets in that zone to see whether all of them or just one are affected.
- Note any fault message on the controller.
- Don't climb into the roof space to look at dampers or ducts.
Services that can help
Read more in our guides
- Ducted zoning explainedZones, dampers, controllers and room sensors in plain terms, plus the airflow limits that decide whether zoning will fix your comfort problem.
- Ducts, outlets and return air: how ducted airflow worksHow supply ducts, outlets and return grilles move air through a ducted system, why sizing, insulation and balancing decide comfort and noise, and failure signs.
Related questions
- Why does my air conditioner turn off by itself?Most often a setting is doing it: an off timer, sleep mode, an eco or quiet mode, or an app schedule someone else set up.
- Why do my heating ducts tick or bang when the heater starts?Light ticking, or a single soft pop as the heating starts or stops, is usually metal parts warming and expanding: the heater's plenum, the return air box, duct collars…
- How do I clean my split system filters?Turn the unit off, lift the front panel, slide the filters out and vacuum off the dust.
- My air conditioner won't respond to the remote. What can I check?Start with the remote: fresh batteries, a clear line to the indoor unit, and no lock symbol or odd mode on its display.
Sources for this answer
1 source, with the date each was checked
- 1.Department of Energy, Environment and Climate Action (energy.vic.gov.au), page last updated 14/04/25: We recommend providing 1.1 to 1.4kW of heating output for every 10m² of your home covered by a ducted system, depending on the individual characteristics of your home. ... We recommend zones for your ducted system, as… Accessed 30 September 2026.
General information for homes in Victoria. Every installation is different, so treat this as a starting point. Where this answer refers to Victorian safety or rental rules, the sources above have the current requirements.