OEM Lennox Furnace Limit Switch — 11G87

The genuine OEM Lennox 11G87 limit switch is a temperature-sensitive safety control that monitors heat inside the furnace and shuts off the burners if the plenum temperature climbs beyond a safe threshold. It also helps coordinate blower operation, energizing the fan once the heat exchanger reaches temperature and de-energizing it after the burners cool. This switch is calibrated to the exact trip and reset points specified for the Lennox furnaces it serves.

When a limit switch fails you may experience a furnace that overheats and shuts down, short-cycling where the burner repeatedly lights and drops out, a blower that runs constantly or won't start, or a unit that stops heating entirely on a lockout. A switch stuck open or drifting out of calibration will interrupt normal operation or, worse, fail to protect against a genuine overheat condition.

Installing an OEM Lennox 11G87 matters because the temperature setpoints are engineered to your equipment's heat exchanger and airflow design. A mismatched aftermarket switch can nuisance-trip, fail to trip when needed, or compromise the safety circuit. The factory part guarantees correct calibration, fit, and full compatibility with your Lennox furnace.