Why does my vacuum cleaner whistle or make a high-pitched sound?

A whistling sound often means air is being pulled through a narrow gap, a partial blockage or an incorrectly fitted part. Switch the cleaner off and unplug it before checking. Do not keep using it if the sound becomes suddenly louder, the machine smells hot or the housing feels too warm.

1. Check that the dust bag, container and filter are fitted properly. Expected result: a correct fit should reduce unwanted air leaks.
2. Inspect the hose and attachments for a partial blockage. Remove any dust or fluff you can reach safely. Expected result: the airflow should sound more even.
3. Look at the joints between the hose, tube and floor head for gaps. Push the parts together firmly. Expected result: the whistle should reduce if air was escaping at a loose connection.
4. Try the cleaner without one accessory at a time, if your setup allows it. Expected result: this can help identify whether one attachment is causing the noise.
5. If the sound persists after these checks, stop using the product and contact the retailer or store where it was purchased.

High-pitched sounds are usually airflow related rather than a sign of normal operation. If they appear suddenly, it is worth treating them as a warning that something is blocked or not seated properly. Generic troubleshooting.