OEM Lennox Draft Inducer Motor Assembly — 74K77

The genuine OEM Lennox 74K77 draft inducer motor assembly draws combustion byproducts through the heat exchanger and vents them safely out of the furnace. It runs at the beginning of each heating cycle to establish draft, and the pressure switch verifies that airflow before the burners are permitted to ignite. The assembly is matched to the exact airflow and electrical requirements of compatible Lennox furnaces.

Common symptoms of a failing inducer motor include loud humming, buzzing, or grinding at startup, a furnace that attempts to start but never lights, and repeated lockouts on a pressure-switch error. Seized bearings, a cracked blower wheel, or an open motor winding are typical failures that leave the system unable to prove draft — and leave your home without heat.

Installing the OEM 74K77 ensures the inducer produces the precise draft your Lennox control board expects and keeps the pressure switch within its rated range. Aftermarket units can under- or over-draft, triggering nuisance lockouts or unsafe venting. The factory part restores dependable ignition, safe combustion, and rated efficiency.