Lennox 25M59 Limit Switch
The Lennox 25M59 Limit Switch is a critical safety component designed for precise thermal monitoring in high-efficiency furnace applications. This L170-30F limit control is engineered to open the electrical circuit at 170°F and automatically reset once the temperature drops by 30°F to 140°F. Featuring a flat flange mount and standard 1/4-inch spade terminals, it ensures a secure fit and reliable electrical connectivity during high-cycle operation. As a genuine Lennox OEM replacement part, it maintains the exact calibration required for the furnace control board to detect overheat conditions caused by restricted airflow or secondary heat exchanger scaling. This prevents damage to the heat exchanger and ensures the system operates within specific thermal tolerances. When troubleshooting a furnace limit switch lockout, verifying the L71-218 cross-reference or 25M5901 part number is essential for maintaining the UL listing and safety integrity of the HVAC equipment.
- Automatic Reset Functionality: The 140-170F range eliminates manual intervention after the plenum temperature stabilizes.
- OEM Reliability: Provides exact Lennox furnace part specifications to prevent premature tripping or contact pitting.
- Standardized Mounting: The universal spade terminal configuration allows for rapid field installation and secure wiring.
- High-Temperature Durability: Constructed with materials designed to withstand the harsh environment of a heat exchanger cabinet.
Common Installation Questions
What causes a Lennox 25M59 to trip frequently?
Frequent tripping is usually indicative of restricted airflow, such as a dirty 4-inch pleated filter, blocked return air grilles, or a failing blower motor capacitor reducing CFM output.
Can I bypass this limit switch for testing purposes?
Bypassing a safety limit is only acceptable for momentary diagnostic continuity checks; the furnace must never be operated in heating mode with a bypassed thermal limit control as it poses a significant fire hazard.
Is the 25M5901 compatible with other brands?
While this is a Lennox specific part number, it cross-references with several Johnson Controls and universal thermal sensors. Always verify the temperature rise rating on the original part's faceplate before substitution.
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.
Original: $16.13
-65%$16.13
$5.65Lennox 25M59 Limit Switch
The Lennox 25M59 Limit Switch is a critical safety component designed for precise thermal monitoring in high-efficiency furnace applications. This L170-30F limit control is engineered to open the electrical circuit at 170°F and automatically reset once the temperature drops by 30°F to 140°F. Featuring a flat flange mount and standard 1/4-inch spade terminals, it ensures a secure fit and reliable electrical connectivity during high-cycle operation. As a genuine Lennox OEM replacement part, it maintains the exact calibration required for the furnace control board to detect overheat conditions caused by restricted airflow or secondary heat exchanger scaling. This prevents damage to the heat exchanger and ensures the system operates within specific thermal tolerances. When troubleshooting a furnace limit switch lockout, verifying the L71-218 cross-reference or 25M5901 part number is essential for maintaining the UL listing and safety integrity of the HVAC equipment.
- Automatic Reset Functionality: The 140-170F range eliminates manual intervention after the plenum temperature stabilizes.
- OEM Reliability: Provides exact Lennox furnace part specifications to prevent premature tripping or contact pitting.
- Standardized Mounting: The universal spade terminal configuration allows for rapid field installation and secure wiring.
- High-Temperature Durability: Constructed with materials designed to withstand the harsh environment of a heat exchanger cabinet.
Common Installation Questions
What causes a Lennox 25M59 to trip frequently?
Frequent tripping is usually indicative of restricted airflow, such as a dirty 4-inch pleated filter, blocked return air grilles, or a failing blower motor capacitor reducing CFM output.
Can I bypass this limit switch for testing purposes?
Bypassing a safety limit is only acceptable for momentary diagnostic continuity checks; the furnace must never be operated in heating mode with a bypassed thermal limit control as it poses a significant fire hazard.
Is the 25M5901 compatible with other brands?
While this is a Lennox specific part number, it cross-references with several Johnson Controls and universal thermal sensors. Always verify the temperature rise rating on the original part's faceplate before substitution.
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.
Product Information
Product Information
Shipping & Returns
Shipping & Returns
Description
The Lennox 25M59 Limit Switch is a critical safety component designed for precise thermal monitoring in high-efficiency furnace applications. This L170-30F limit control is engineered to open the electrical circuit at 170°F and automatically reset once the temperature drops by 30°F to 140°F. Featuring a flat flange mount and standard 1/4-inch spade terminals, it ensures a secure fit and reliable electrical connectivity during high-cycle operation. As a genuine Lennox OEM replacement part, it maintains the exact calibration required for the furnace control board to detect overheat conditions caused by restricted airflow or secondary heat exchanger scaling. This prevents damage to the heat exchanger and ensures the system operates within specific thermal tolerances. When troubleshooting a furnace limit switch lockout, verifying the L71-218 cross-reference or 25M5901 part number is essential for maintaining the UL listing and safety integrity of the HVAC equipment.
- Automatic Reset Functionality: The 140-170F range eliminates manual intervention after the plenum temperature stabilizes.
- OEM Reliability: Provides exact Lennox furnace part specifications to prevent premature tripping or contact pitting.
- Standardized Mounting: The universal spade terminal configuration allows for rapid field installation and secure wiring.
- High-Temperature Durability: Constructed with materials designed to withstand the harsh environment of a heat exchanger cabinet.
Common Installation Questions
What causes a Lennox 25M59 to trip frequently?
Frequent tripping is usually indicative of restricted airflow, such as a dirty 4-inch pleated filter, blocked return air grilles, or a failing blower motor capacitor reducing CFM output.
Can I bypass this limit switch for testing purposes?
Bypassing a safety limit is only acceptable for momentary diagnostic continuity checks; the furnace must never be operated in heating mode with a bypassed thermal limit control as it poses a significant fire hazard.
Is the 25M5901 compatible with other brands?
While this is a Lennox specific part number, it cross-references with several Johnson Controls and universal thermal sensors. Always verify the temperature rise rating on the original part's faceplate before substitution.
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.
