Lennox 93W73 Limit Switch

The Lennox 93W73 Limit Switch is a critical safety component designed for precise thermal regulation within residential gas furnaces and air handlers. Engineered as a normally closed thermal switch, this fixed-temperature limit control is calibrated to open at 140°F, effectively interrupting the burner circuit if the heat exchanger temperatures exceed safe operational parameters. This specific Lennox furnace replacement part features a high-reliability bimetal disc assembly that ensures rapid response times to airflow obstructions or blower failures. For field technicians, the 93W73 serves as a drop-in HVAC high limit sensor across various G40, G43, and G50 series units, maintaining consistent system pressure and preventing structural damage to the heat exchanger. Proper installation of this internal component limit is essential for maintaining UL compliance and ensuring the furnace operates within its designated temperature rise range. Ensure all electrical connections are secure and the mounting flange is flush to prevent bypass air from affecting the 140-degree trip point.

Technical Key Benefits

• Precise 140°F Trip Point: Calibrated for accurate over-temperature protection to prevent heat exchanger stress.
• Automatic Reset Functionality: Resets the circuit once temperatures drop below the differential threshold, ensuring system restoration after cooling.
• Direct OEM Compatibility: Specifically designed for Lennox heating systems, eliminating the need for field modifications or bracket adjustments.
• Durable Bimetal Construction: Built to withstand high-cycle environments common in forced-air applications.

Common Technical Questions

What causes a Lennox 93W73 to trip frequently?
Repeated tripping usually indicates restricted airflow, often caused by a dirty air filter, blocked return ducts, or a failing blower motor assembly rather than a fault in the 140F switch itself.

Can I bypass the limit switch for testing?
A limit switch should never be bypassed during permanent operation. Temporary bypassing is only for diagnostic continuity verification by a qualified technician to confirm if the switch has failed open.

Are there specific tools required for replacing this limit control?
Replacement typically requires standard 1/4" or 5/16" nut drivers, depending on the furnace cabinet screws, and standard spade connectors for the wiring harness.

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.