OEM Lennox Draft Inducer Blower Motor — 21L90

The genuine OEM Lennox 21L90 draft inducer blower motor is responsible for moving combustion byproducts through the heat exchanger and out the venting system. At the beginning of every heating cycle it spins up to create negative pressure, closing the pressure switch that confirms safe draft before the burners are permitted to ignite.

Common failure symptoms: As the 21L90 ages, worn bearings can cause loud humming, squealing, or rattling noises, and the motor may spin slowly, seize, or hum without turning. Since the furnace relies on this motor to prove venting, a failing inducer frequently shows up as a pressure-switch error, repeated ignition lockouts, or a complete no-heat condition.

Why OEM matters: Lennox engineers the 21L90 to deliver the exact draft, airflow, and RPM its combustion system and pressure switch are calibrated for. Generic replacements that fall short on airflow can fail to close the pressure switch, leading to unreliable operation and nuisance lockouts. The OEM 21L90 ensures a correct bolt-in fit, matched performance, and safe, efficient venting for compatible Lennox, Armstrong, and Ducane furnaces.