Brisbane reasons to look at the ducts
Humid air and the indoor unit
Mitsubishi Electric says dirt or dust inside an air conditioner can cause odours, help mould grow and clog the drain. With Brisbane's summer dew points around 20 degrees, have the indoor unit and its drain looked at before you blame the ducts.
Ducts under the house
The ACT Government says a ducted unit usually sits in the ceiling or under the house. Under a high-set Brisbane home, ducts that floodwater reached in 2022 need inspecting before anyone talks about cleaning them.
Renovation dust
Wikipedia's Queenslander article notes many verandahs and under-house areas have been closed in as rooms. Sanding and plastering with the system running sends dust into the ducts, which is a fair reason for a clean.
Three things to check before you pay for a clean
The return air filter. It sits behind the big grille that draws air back to the unit, and it's meant to catch dust before it goes any further. Clean or replace it as the manual says, with the system off, and see whether the problem changes.
The indoor unit and drain. On a ducted reverse cycle system, damp inside the unit itself is a common source of smells. A technician can check the coil and drain tray during a service.
The ducts themselves. A crushed, split or disconnected duct won't be fixed by cleaning. If one room has weak airflow, ask for the runs to be inspected and see our page on ducts, vents and filters.
Ask a duct cleaner before you book
- Will you inspect the system before giving me a quote?
- What method do you use on flexible ducting, and how do you avoid tearing it?
- Do you use crawl boards in the roof space?
- If ducts are damaged or were flooded, will you show me with photos?
- In an older house, how do you check for asbestos before disturbing anything?
What you can do, and what to leave
You can
- Wipe or vacuum the outlet grilles you can reach from the floor.
- Clean the return air filter on your manual's schedule, with the system switched off.
- If the underfloor flooded, leave the system off until it's been inspected.
Leave to a licensed installer
- Cleaning inside the duct runs.
- Anything in the roof space. WorkSafe Victoria warns that workers fall through plaster ceilings up there.
- Cleaning inside the indoor unit.
- Any work where asbestos might be present.
What we'd do
Our take
We'd clean the return air filter and the grilles, run the system for a day and see whether the dust or smell is still there. If it is, or if the ducts sat in floodwater, we'd book an inspection first and pay for a clean only if the ducts are sound. Where they're crushed or waterlogged, we'd have them repaired or replaced rather than cleaned.
