The answer to 'how does air handler work' is that an air handler is the indoor unit of a central air conditioning or heat pump system that circulates air through the ductwork in your home. The air handler contains the blower fan that pulls air from your home, passes it through the air filter, and then pushes the conditioned air back out into your living spaces. It works in conjunction with the outdoor compressor unit to either cool or heat the air as needed.
The air handler has several key components that work together to move and condition the air, including the blower, air filter, and heating/cooling coils. The blower motor pulls air from your home's return vents, the air filter captures dust and debris, and the coils either cool or heat the air before it's distributed back through the supply vents. Some air handlers also have an electric heating element to provide supplemental heat when needed.