OEM Lennox Limit Switch — 23G38

The genuine OEM Lennox 23G38 limit switch is a critical safety control that monitors temperature inside the furnace heat exchanger and plenum. When the temperature climbs beyond a safe threshold — typically from restricted airflow — the switch opens and shuts off the burners to prevent overheating, protecting the heat exchanger and your home.

A failed limit switch produces telltale symptoms: the furnace short-cycles (burners light then quickly shut off), the blower runs continuously, or you get no heat at all as the switch trips prematurely on a dirty filter, blocked ducts, or a failing blower. A switch that has burned open or drifted out of calibration will lock the furnace out even when temperatures are normal.

Using the OEM 23G38 is essential because it is calibrated to the exact trip and reset temperatures Lennox engineered for your furnace model. A generic switch with the wrong temperature rating can either nuisance-trip or, worse, fail to open when it should — defeating the safety function. The factory-correct part restores reliable, code-compliant overheat protection.