Why does my air conditioner smell dusty or stale when I switch it on?

A dusty or stale smell at start-up is often linked to a dirty filter or a unit that has been stored for some time. It is sensible to check the air filter first, then review how the appliance was cleaned and stored before using it again.

Check the air filter

1. Switch the unit off and unplug it.
2. Open the air inlet grille and remove the filter.
3. Clean it in lukewarm water with neutral detergent, then let it dry away from direct sunlight. The manuals recommend cleaning the air filter about once every two weeks.

Expected result

After cleaning and drying, airflow should feel fresher and more even. If the smell reduces after the first run, the filter was likely the main cause.

Look for storage-related causes

1. Check that the unit was stored dry and covered from dust.
2. Inspect the outlet and intake areas for lint or pet hair.
3. Run the unit briefly in a well-ventilated room and observe whether the odour fades.

When to stop using it

Stop using the air conditioner if the smell is electrical, sharp or chemical, or if the unit becomes unusually hot. If the odour remains after cleaning and short testing, contact the retailer or store where it was purchased for advice on the next steps.