Air handler
The indoor blower unit that moves conditioned air through your ducts — the partner to an outdoor AC or heat pump.
An air handler is the indoor half of a split system: a cabinet holding the blower fan and the [evaporator coil](/glossary/evaporator-coil) that distributes cooled (or heated) air through your ductwork. In homes with a furnace, the furnace's blower does this job and the coil sits on top of it; in homes without a furnace — common with a [heat pump](/glossary/heat-pump) — a dedicated air handler fills the role. When you [replace a central AC](/guides/central-ac-replacement-cost), the air handler or furnace coil is often replaced at the same time so the system stays a matched, warrantied pair; a standalone air handler typically adds $1,500–3,500 to the job. A failing blower motor, rattling cabinet, or weak airflow at the vents usually points here.