What Is an Air Handler?

The air handler is the indoor cabinet containing the blower, the evaporator coil and, in many electric systems, backup heat strips. In a heat-pump installation it takes the place a furnace would occupy, moving conditioned air into the duct system.

Also called: fan coil · indoor unit

Why it matters to you

Where the air handler sits matters in coastal construction. Units in unconditioned attics or vented crawl spaces work against humid air on both sides of the cabinet, and duct runs in those spaces pick up heat and moisture before the air reaches the room.

What to do about it

Check that the cabinet and connected ducts are sealed and insulated, especially in an attic or crawl space. Listen for a blower that cannot reach speed — that usually points to static pressure or a filter problem rather than the blower itself.