OEM Lennox Limit Switch — 45H83

The genuine OEM Lennox 45H83 limit switch is a critical safety control that monitors the temperature inside your furnace heat exchanger. If the unit overheats due to restricted airflow or a blower failure, the limit switch shuts off the burners to prevent damage to the heat exchanger and reduce fire risk, then automatically resets once temperatures return to a safe range.

When a limit switch fails or becomes worn, you may notice the furnace short-cycling (burners igniting and shutting off repeatedly), the blower running continuously, no heat at all, or the system locking out on a limit fault code. A faulty switch can either trip prematurely and leave you without heat, or fail to open when it should — allowing dangerous overheating.

Because it is a safety device, using the OEM Lennox 45H83 is essential. It is calibrated to the exact trip and reset temperatures your furnace requires, ensuring reliable protection. Generic limit switches with different temperature ratings can cause nuisance shutdowns or, worse, fail to protect the heat exchanger. The factory part restores safe, dependable operation for your Lennox furnace.