What should I do if my air purifier is making noise and air output is less?

The filters are likely dirty. High amounts of particles can block the pores in the filter and stop air from moving through it. Replace the filters with certified Honeywell replacement filters—HEPA filters every year and Pre-Filter/Enhanced Odor & VOC filters every 3 months. Individual home conditions may vary, so check filters periodically to ensure proper unit performance. (Page 9)