OEM Lennox Limit Switch — 25M59

The genuine OEM Lennox 25M59 limit switch is a critical high-temperature safety control that monitors the heat exchanger and plenum temperature in your Lennox furnace. When temperatures rise beyond safe operating limits, this switch interrupts the gas valve or burner circuit to prevent overheating, protecting both your equipment and your home. It is engineered to the exact temperature set point and electrical rating specified for your Lennox system.

Common failure symptoms: a furnace that short-cycles (repeatedly turning on and off), no heat output, the blower running continuously, or the unit tripping on a limit fault. A limit switch that fails open will lock out the burners entirely, while a switch that sticks closed defeats a vital safety function.

Why OEM matters: Lennox limit switches are calibrated to precise trip temperatures matched to your furnace's heat exchanger design. Installing a generic substitute with the wrong set point can cause nuisance lockouts or, worse, allow unsafe operation. Choosing the OEM 25M59 guarantees correct calibration, proper fit, and full compatibility with your Lennox equipment.