OEM Lennox Relay — 10B17

The genuine OEM Lennox 10B17 relay is an electromechanical switch that lets a low-voltage control signal energize a higher-voltage load inside your Lennox furnace, air handler, or package unit. When the thermostat or control board calls, the relay's coil closes its contacts to route power to components such as the blower motor, fan, or heating stage — making it a small but essential link in the equipment's control sequence.

Common failure symptoms: A failing relay can leave a blower or fan that won't start, won't shut off, or cycles erratically. You may hear repeated clicking or chattering, notice a burnt-plastic smell, or see pitted, welded contacts. Because it controls when major components turn on, a bad relay often mimics a failed motor or control board, so it's worth verifying before replacing costlier parts.

Why OEM matters: The 10B17 is rated for the exact coil voltage, contact amperage, and terminal configuration your Lennox system expects. A generic relay with the wrong rating or pinout can drop out under load, weld shut, or damage what it switches. Installing the factory part restores reliable, safe switching and keeps your Lennox control sequence operating as designed.