Here are the following things you can do remove the unusual noise on the fan of your unit:

1. Make sure the filters are properly in place with plastic packaging removed.
2. Make sure the air purifier is operating on a hard, flat, level surface.
3. Replace the filters.
4. The air purifier may be damaged, or a foreign object may be inside. Stop using the air purifier and contact Customer Support at customersupport@focusglobalinc.com. Do NOT try to repair the air purifier.