Lennox 49L03 Limit Switch

The Lennox 49L03 Limit Switch is a critical safety component engineered for precision temperature regulation in Lennox residential furnaces and commercial HVAC systems. This 7-inch insert limit switch serves as a primary high-limit control, featuring a fixed temperature range that opens at 200°F and automatically resets when the internal temperature drops to 170°F. As a Normally Closed (NC) SPST switch, it provides essential protection by interrupting the burner circuit during an overheat event, preventing heat exchanger damage and ensuring safe equipment operation.

Designed for professional-grade reliability, the 49L03 is the OEM direct replacement for 49L0301, 27K15, 27K13, 27K1501, and 27K1301. It is also compatible with select Allied, Armstrong, Concord, and Ducane equipment. This automatic reset limit switch features a robust board-mount design, facilitating a seamless fit within the blower housing or heat exchanger vestibule. For technicians troubleshooting frequent furnace limit switch tripping or identifying Lennox furnace error codes related to overheating, this genuine Lennox replacement part restores factory-spec thermal protection and system efficiency.

• Precise Thermal Calibration: Engineered with a 200°F open and 170°F close threshold to maintain strict safety parameters within the combustion chamber.
• Universal OEM Compatibility: Serves as the factory-authorized replacement for multiple legacy Lennox furnace parts, including the 49L0301 and 27K15.
• Durable 7-Inch Probe: The extended insert length allows for accurate sensing of core temperatures in varied furnace cabinet configurations.
• Automated System Recovery: The automatic reset functionality eliminates the need for manual intervention once temperatures return to safe operating levels.

What causes a Lennox limit switch to trip frequently?
Repeated tripping is often indicative of restricted airflow. Check for a dirty air filter, blocked return air ducts, or a failing blower motor that is preventing heat from being moved away from the heat exchanger.

Is the 49L03 interchangeable with a manual reset switch?
No. While the 49L03 is an auto-reset switch, it must only be used in applications where the original manufacturer specifications call for an automatic reset high-limit control. Always verify the part number in the service manual.

How do I test if the 49L03 is faulty?
With the power off, use a multimeter to check for continuity across the terminals. Since it is a Normally Closed switch, you should read 0 ohms at room temperature. If the switch remains open (infinite resistance) while cool, it requires replacement.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.