Your central air conditioning system                   consists of two parts. An outdoor unit and        an indoor unit. The air handler is the indoor             unit that circulates conditioned air throughout                 your home. An air handler paired with an                        air conditioner circulates cool air                      throughout your house during the summer                      months. When an air handler is matched                          with a heat pump, it works all year long,                 circulating cool air in the summer, and                             warm air in the winter. The air handler                 consists of a coil and an air blower.