Levoit Core 400S airflow is significantly reduced
Cause 1 of 3Airflow is significantly reduced. Source: Troubleshooting, p. 15
First checkMake sure the filter is removed from its packaging and properly in place.
Causes and checks
Airflow is significantly reduced. Source: Troubleshooting, p. 15
- Make sure the filter is removed from its packaging and properly in place.
- Tap the Fan Speed button to increase the fan speed.
- Leave 15 inches (38 cm) of clearance on all sides of the air purifier.
The pre-filter may be clogged by large particles, such as hair or lint, blocking airflow. Source: Troubleshooting, p. 15
- Clean the pre-filter. See Clean the pre-filter.
The filter may need replacing. Source: Troubleshooting, p. 15
- Replace the filter. See Replace the filter.
All 3 causes checked. Contact Levoit Customer Support: 1-888-726-8520.
Service
If the checks above do not clear it, contact Levoit Customer Support: 1-888-726-8520, support.levoit.com. United States (Monday to Friday, 9:00 am to 5:00 pm PST/PDT). Source: Customer Support, p. 22
Other Core 400S problems
- Air purifier will not turn on or respond to buttons2 causes in the manual. First: the purifier gets no power, or the power cord is damaged.
- Air purifier makes an unusual noise while the fan is on3 causes in the manual. First: the filter or the surface under the purifier may cause the noise.
- Strange smell coming from the air purifierStrange smell coming from the air purifier.
- Poor air purification quality3 causes in the manual. First: the room is larger than 403 ft² (37 m²), so air purification takes longer.
- Air quality indicator always stays red2 causes in the manual. First: the AirSight Plus Laser Dust Sensor may need to be cleaned. Dust blocking the sensor affects its accuracy.
- Air quality indicator always stays blue when the air is poorThe AirSight Plus Laser Dust Sensor detects airborne particles but cannot detect gas.
- Purifier will not connect to the VeSync app5 causes in the manual. First: the phone's Bluetooth is off, or the phone is connected to another Bluetooth device.
- Purifier shows offline in the VeSync app2 causes in the manual. First: the purifier is offline.
Sources
- User Manual, Core 400S smart air purifier. Arovast Corporation. Document HEAPAPLVSUS0162Y, revision A1-241202, 24 pages, en-US. levoit.com (PDF). Listed on the manufacturer's support page. Retrieved 13 November 2026.
Page numbers are the numbers printed in the manual. Where this page and the manual differ, follow the manual.