A: Troubleshooting steps:
1-Check the protection status: Status → Protection Status → Filter clogged (normally it is CLOSE; alarm is OPEN).
2-If the status is OPEN, manually reset the alarm and observe whether the status in step 1 changes.
3-If it changes, the alarm logic is fine; other components (filter, differential pressure switch) need to be checked.
4-After resetting the alarm, open the rear door and observe whether the alarm reappears.
5-If the alarm continues to appear, it means the issue is unrelated to the filter; the airflow switch needs to be checked.
6-Check whether the detection port of the airflow switch is blocked, and whether the airflow switch threshold setting is correct.