Air handling unit, used for the heating, cooling, and filtering the air.
Air cleaning and filtration is an important factor of our indoor environment because cleaning the air filters out what the lungs cannot by removing particles, contaminants, vapors and gases from the air. The filtered and cleaned air then is used in heating, ventilation and air conditioning.
Clean air delivery rate is the amount of clean air an air cleaner provides to a room or space.

Filter performance depends on the size of the particle or fiber, the filter packing density and depth and also the air flow rate. For central air conditioners, filters are generally located somewhere along the return duct's length. Common filter locations are in walls, ceilings, furnaces, or in the air conditioner itself.

Some types of filters are reusable; others must be replaced. They are available in a variety of types and efficiencies. Filters may need more frequent attention if the air conditioner is in constant use, is subjected to dusty conditions, or you have fur-bearing pets in the house. generally speaking it's best to clean or change your filters once every 3 to 9 months. Remember, regular cleaning/changing of your filter will ensure the best filtration, increase the life of your machine, and give you peace of mind that you're breathing easier.
To clean your filter, simply remove your filter and then rinse or vacuum it. If you rinse the collection cells, allow them to dry thoroughly before replacing them.

The most important thing is that an air conditioner's filters, coils, and fins require regular maintenance for the unit to function effectively and efficiently throughout its years of service. Neglecting necessary maintenance ensures a steady decline in air conditioning performance while energy use steadily increases.