Check the fan is moving air
With the fan running, hold a single sheet of tissue against the grille. A working fan pulls it flat and holds it there. If the tissue barely moves, the fan isn't moving much air. Look at the grille too. A grey layer of lint and dust across it, and on the blades behind it, cuts airflow a lot, and it builds up faster when the fan sits right above the shower.
Try the tissue test with the door shut, then with it slightly open. If the steam clears much better with the door ajar, the room is starved of replacement air, and a gap under the door, or leaving it open while the fan runs on, fixes it.
Problems you can't see from the room
Flexible duct crossing the roof space gets crushed by people walking through, sags into loops that collect water, or drops off the fan or the outlet altogether. Many fans have a small backdraft flap at the outlet that can stick shut with grime, and the vent on the roof or wall can be blocked by a nest, leaves or paint. Any of these leaves the fan spinning but going nowhere.
A fan that sounds louder or slower than it used to may have worn bearings, which also cut airflow. If the steam problem started after insulation, roof work or new lights went in, suspect the duct first.
When the fan is the wrong size
If the duct is clear and the fan still can't keep up, it may be too small for the room, or the duct may be too long with too many bends for that fan. A small fan meant for a toilet won't clear a large ensuite with a double shower. Replacing the fan or re-running the duct is electrical work for a licensed electrician, who issues a Certificate of Electrical Safety.
What you can safely do now
- Try the tissue test with the fan running, first with the door shut and then slightly open.
- With the fan switched off, vacuum the grille with a brush attachment.
- Run the fan during the shower and for a while after it.
- If a gas heater is on in the house, turn it off before using the exhaust fan.
- If the fan smells hot or grinds, switch it off and leave it off.
Services that can help
Read more in our guides
Related questions
- Why does my bathroom heat lamp turn itself off?Most heat lamp and 3-in-1 units have a thermal cut-out that switches the heat off when the unit gets too hot, then lets it come back once it cools.
- Why does my ceiling fan work but the light doesn't?If the fan runs but its light doesn't, the fault is on the light side: a failed globe or LED module, a light setting on the remote or wall control, or a loose connection…
- Can a power point be added to my kitchen island?Usually, yes.
- My power point cover is cracked. Is it safe to use?No.
Sources for this answer
2 sources, with the date each was checked
- 1.Energy Safe Victoria: Don’t use kitchen rangehoods or bathroom exhaust fans at the same time as your heater. It can create a negative pressure environment, drawing carbon monoxide into living spaces. Accessed 30 September 2026.
- 2.Energy Safe Victoria: Whenever a licensed electrician completes any electrical installation work, they must provide a Certificate of Electrical Safety (COES). 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.