Carrier HH18HA170 Limit Switch

The Carrier HH18HA170 Limit Switch is a critical safety component designed for precise thermal monitoring in residential and commercial HVAC furnaces. This genuine OEM replacement part features an L170-40F specification, meaning it is calibrated to open the electrical circuit when the internal temperature reaches 170°F and automatically reset once the temperature drops by 40°F (resetting at 130°F). Engineered for high-limit protection, this switch prevents heat exchanger damage and potential fire hazards by interrupting the burner floor circuit during restricted airflow or over-fired conditions.

For service technicians, the HH18HA170 provides a plug-and-play solution to common furnace limit switch tripping issues, such as short-cycling or blower motor run-on. The thermal disc sensor is built with premium materials to resist carbon buildup and fatigue in high-cycle environments. Maintaining correct temperature limit switch calibration is essential for system longevity and meeting factory safety protocols. This part is compatible with a wide range of Carrier, Bryant, and Payne gas-fired equipment, ensuring HVAC safety control remains uncompromised.

• Precise Thermal Calibration: Fixed 170°F trip point ensures your equipment operates within engineered safety margins.
• Automatic Reset Logic: Features a 40°F differential for reliable system recovery without manual intervention.
• Direct OEM Fit: Guaranteed physical and electrical compatibility with Carrier-family gas furnaces, eliminating field modifications.
• Enhanced System Safety: Critical for preventing heat exchanger overheating during air filter blockages or blower failures.

• Will this fix a furnace that keeps shutting off before reaching the thermostat setpoint? Yes, if the existing switch is faulty or sensing a true over-temperature condition, replacing it with the HH18HA170 restores correct safety limits.
• Does this switch require a manual reset button? No, the L170-40F is an automatic reset switch that re-engages the circuit once the plenum cools down to 130°F.
• Can this be used in other brands? While designed for Carrier/Bryant/Payne, it can be used in any application requiring an L170-40F limit switch with matching mounting footprints.

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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.