OEM Lennox Limit Switch — 18K44

The genuine OEM Lennox 18K44 limit switch is a factory safety component that guards your Lennox furnace against overheating. Mounted on the heat exchanger or in the blower compartment, it senses temperature and interrupts the burner circuit if heat rises beyond safe limits, then automatically resets once temperatures return to normal. This exact-fit replacement is built to Lennox specifications for dependable performance.

Common failure symptoms: A failing 18K44 often causes the furnace to short-cycle, produce no heat, or lock out on repeated safety trips. You may also see the blower running non-stop or the burners lighting and then shutting down after a few seconds. Dust buildup, a restricted air filter, or normal contact wear can all cause the switch to trip prematurely or fail entirely.

Why OEM matters: The 18K44 is calibrated to a specific trip temperature matched to your furnace model. Generic replacements with incorrect ratings risk nuisance shutoffs or compromised overheat protection. Installing the authentic OEM part keeps your Lennox safety circuit accurate and reliable, ensuring proper furnace operation and long-term equipment protection.