A frequently used projector continuously shows a message to clean the air filters.

The message to clean the air filters, despite them being clean, is likely due to the projector's preconfigured settings related to the hours of use. Many projectors have maintenance reminders that trigger based on usage hours to prompt regular cleaning and maintenance. This reminder may need to be reset after checking or cleaning the filters. Adjusting the maintenance reminder or resetting the hours of use counter in the projector's settings can resolve the issue. This approach is consistent with the troubleshooting principles outlined in the CompTIA A+ Core 1 (220-1101) Exam Objectives under section 5.4 "Given a scenario troubleshoot video, projector, and display issues", where it's advised to consider all potential causes, including preconfigured settings, when diagnosing display-related problems .