The Carrier HH19ZA155 Limit Switch is a critical safety component designed for precise thermal monitoring in residential and commercial HVAC systems. Engineered for automatic reset functionality, this disc-style switch features a normally closed circuit that opens upon reaching its fixed setpoint of 155°F to prevent heat exchanger damage and potential fire hazards. Once the system temperature drops to the 115°F close threshold, the circuit re-engages, allowing for a resumption of the heating cycle. As a genuine OEM replacement part, the HH19ZA155 ensures seamless compatibility and restores factory-standard operating parameters to furnaces, heat pumps, and packaged units. This furnace high limit switch is built with a compact 2.2-inch profile, making it suitable for tight clearance installations behind the blower housing or near the heat exchanger. Technicians often source this specific Carrier replacement part to resolve short-cycling issues caused by restricted airflow or failing safety sensors.

Key Benefits

• Precision Thermal Calibration: Designed to open at exactly 155 degrees Fahrenheit and close at 115 degrees Fahrenheit for reliable safety lockouts.
• Broad Compatibility: Directly replaces multiple Carrier furnace parts, including HH19ZA455, HH18680001, and P331-2113 models.
• Automatic Reset: Eliminates the need for manual intervention by resetting the circuit automatically once safe temperatures are restored.
• OEM Reliability: Ensures the HVAC limit switch meets original equipment specifications for response time and durability.
• Safety Compliance: Crucial for preventing the blower motor from circulating overheated air or the burners from operating in unsafe conditions.

Common Questions

What causes a Carrier HH19ZA155 to trip frequently?
Repeated tripping is usually a symptom of restricted airflow. Check for dirty air filters, blocked return registers, or a failing blower motor that cannot move enough air across the heat exchanger, causing temperatures to exceed the 155F open point.

How can I tell if this limit switch is defective?
A veteran technician will test for continuity using a multimeter while the furnace is cold. If the circuit is open at room temperature, the internal bimetal disc or contacts have likely failed, requiring a limit switch replacement.

Will this work in place of a manual reset limit switch?
No. The HH19ZA155 is an automatic reset switch. You should never substitute an automatic switch for a manual "rollout" switch, as they serve different safety functions within the combustion sequence.

Item is Non Cancelable / Non Returnable

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.