Carrier HH18HA195 Limit Switch

The Carrier HH18HA195 Limit Switch is a critical safety component designed for furnace high-temperature protection. This factory-spec manual reset limit switch features a snap disc design that is calibrated to open the electrical circuit at a precise 195°F cutout temperature. As a normally closed (NC) SPST switch, it maintains continuity during standard heating cycles but breaks the 24V or line voltage circuit to the gas valve or inducer motor if an overheat condition occurs, such as a failing blower motor or a restricted return air filter.

This OEM replacement part serves as a direct cross-reference for numerous Carrier, Bryant, and Payne models, specifically replacing legacy part number P331-2162. Its manual reset capability is a vital diagnostic feature for technicians, as it requires physical intervention after a trip, ensuring the underlying cause of the high-limit excursion is addressed before the system resumes operation. Rated for up to 10A at 120VAC, this switch is built for thermal stability and rapid response in high-cycle environments.

• Precise Thermal Calibration: Calibrated to open at 195°F and close at 115°F to ensure rigorous safety standards for Carrier furnace parts.
• Manual Reset Feature: Prevents automatic restarts after an overheat event, allowing technicians to diagnose airflow or combustion issues effectively.
• OEM Compatibility: Guaranteed fit for systems requiring HH18HA195 or HH18HA134, eliminating the need for field modifications.
• Heavy-Duty Construction: Built to withstand the harsh thermal environment of a draft inducer safeguard or heat exchanger housing.

How do I know if the HH18HA195 limit switch has tripped?
If your furnace blower runs continuously but the burners fail to ignite, or if the system is throwing a code for an open high-limit circuit, check the manual reset button on the back of the switch. If it clicks when pressed, the switch had reached its 195-degree threshold.

Can I replace an auto-reset switch with this manual reset HH18HA195?
No. You should always replace like-for-like as specified by the manufacturer's data sheet. Manual reset switches are often used as secondary safeguards in specific locations where a trip indicates a serious mechanical failure.

What causes this limit switch to frequent trip?
Common causes include a clogged air filter, a failing indoor blower motor, obstructed ductwork, or an over-fired burner. Always verify static pressure and temperature rise across the heat exchanger when replacing this component.

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.