my honeywell hpa300 air purifier is making a weird rattling noise, is the filter broken?

A rattling noise is almost always a loose filter. The pre-filter or HEPA filter isn't seated correctly.

1. Unplug the unit.
2. Remove the rear grille.
3. Take out the HEPA filter and carbon pre-filter. Check both for any tears or damage.
4. Reinsert the carbon pre-filter first, ensuring it's flat against the back of the unit.
5. Reinsert the HEPA filter, pressing firmly around all edges to ensure a tight seal.
6. Replace the grille and plug it back in.

IF THAT DIDN'T WORK: The noise could be a foreign object like a small toy or piece of debris inside the unit or caught in the fan blades. Unplug it and inspect the interior cavity and fan area with a flashlight. Remove any obstructions.

HEADS UP: A continuously loose filter reduces cleaning efficiency and strains the motor. Make sure the grille clicks securely into place after every filter check.