Have you recently inspected and possibly changed out your HVAC Filters?
Many experts recommending changing the filters monthly, but that’s not always necessary. For smaller families without pets or allergies, you’ll likely be okay changing the filters every 2-3 months. If the filter is dirty, change it out, otherwise inspect it again next month. I personally use a permanent marker to write the date I replace my filter so I can remember when I last replaced it.
Filter efficiency and performance is often indicated by the filters' minimum efficiency reporting value, or MERV rating. Standard MERV values range from 1 to 16, with the number serving as an indicator of how well the filter will remove material from the air. Higher MERV numbers indicate better filtration. The higher your filtration number the better your chances at capturing allergens, dust and bacteria.