Lennox 26G78 Limit Switch

The Lennox 26G78 is a high-performance 185F AUTO limit switch engineered for critical temperature regulation in residential and commercial HVAC units. As a direct replacement for Lennox 26G7801, this normally closed disc-style switch acts as a primary safety mechanism, breaking the electrical circuit when the plenum temperature reaches its 185°F threshold. Designed for rapid response, the automatic reset furnace limit restores connectivity once temperatures return to safe operating parameters, preventing equipment cycling issues and heat exchanger damage. This OEM Lennox replacement part is built to the TOD 61F series standard, ensuring seamless integration with existing wiring harnesses and mounting brackets. Field technicians and contractors rely on the Lennox 26G78 high limit control for its precise calibration and durability in high-cycle environments. Whether you are servicing an Allied, Armstrong, or Ducane furnace, this universal-fit limit switch provides the exact thermal protection required to maintain system integrity and prevent dangerous overheating conditions during the heating cycle.

• Precise Thermal Protection: Features a fixed 185°F trip point to safeguard the heat exchanger from excessive thermal stress.
• OEM Compatibility: Replaces multiple legacy part numbers including 26G7801, 58H78, 52A94, and 322801 for versatile field application.
• Automatic Reset Logic: Eliminates the need for manual intervention by resetting the circuit automatically after the cooling phase.
• Rugged Disc Construction: The 61F series design provides reliable switching performance under varied atmospheric conditions.
• Direct Fit Installation: Standard mounting footprint allows for quick swap-outs during emergency service calls.

Is the Lennox 26G78 interchangeable with the 26G7801?
Yes, the 26G78 is technically identical to the 26G7801 and serves as the current standard replacement part for Lennox and Allied Air equipment.

What causes this limit switch to trip frequently?
Repeated tripping of the 185-degree limit switch usually indicates restricted airflow, often caused by a dirty air filter, blocked return air, or a failing blower motor.

How do I verify if the 26G78 is the correct part for my furnace?
Check the stamping on your existing switch. If it indicates an L185F (Limit 185°F) and matches the 61F series physical profile, the 26G78 is the appropriate technical 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.