The Carrier HH18HA470 is a high-precision HVAC auto limit switch engineered to provide critical over-temperature protection in residential and commercial gas furnaces. As a genuine Carrier OEM replacement part, this component is designed to monitor internal plenum temperatures, automatically opening the circuit if the heat exchanger exceeds the 170°F safety threshold. This 100-170F auto limit switch ensures that equipment operation remains within safe thermal parameters, preventing damage to the heat exchanger and potential fire hazards. Using HH18HA470 furnace part specifications ensures seamless HVAC system compatibility with Bryant and Payne models, maintaining the original safety certification of the appliance.

This automatic reset limit switch eliminates the need for manual intervention after a temporary overheat condition, once the system cools to the 100°F reset point. For technicians troubleshooting Carrier furnace limit switch faults, this part is a direct drop-in for problematic bimetal sensors that have drifted out of calibration. Its compact footprint and OEM furnace safety switch construction make it the standard choice for reliable high-limit protection in high-efficiency heating cycles.

• Precise Thermal Control: Factory-calibrated to open at 170°F and reset at 100°F for consistent safety cycles.
• Durable Bimetal Construction: Designed to withstand the rapid thermal cycling inherent in modern furnace heat exchangers.
• Universal Application: Compatible with a wide range of Carrier, Bryant, and Payne gas heating units.
• Automatic Recovery: Resumes system operation automatically once safe temperatures are restored, reducing unnecessary service calls.

Common Questions

How do I know if my HH18HA470 limit switch is bad?
Technicians should check for continuity across the terminals when the system is cool; an open circuit at room temperature indicates a failed switch. Additionally, if the furnace blower runs continuously while the burners fail to ignite, the limit switch may be stuck in the open position.

Will this switch fix a Code 33 on my Carrier furnace?
A Code 33 typically indicates a limit circuit lockout. While the Carrier HH18HA470 is the primary safety device in that circuit, you must also verify that the air filter is clean and the blower motor is moving sufficient CFM, as restricted airflow is the most common cause of limit trips.

Is the HH18HA470 a manual or auto reset switch?
This is an automatic reset switch. Unlike flame rollout switches that require a physical button press, this unit restores electrical flow automatically once the temperature drops below 100°F.

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.