An air handler system is a device used to regulate and circulate air as part of a heating, ventilating, and air-conditioning (HVAC) system. It is typically a large metal box containing a blower, heating or cooling elements, filter racks or chambers, sound attenuators, and dampers. Air handlers are usually connected to a ductwork ventilation system that distributes the conditioned air through the building and returns it to the air handler. The air handler is responsible for providing conditioned air to the building, controlling the temperature and humidity, and providing fresh air for ventilation. It also helps to reduce energy costs by providing a more efficient system for heating and cooling. The air handler is an essential component of any HVAC system, and its performance can have a significant impact on the comfort and energy efficiency of a building.