Carrier HH18HA454 Limit Switch

The Carrier HH18HA454 Limit Switch is a critical safety component designed for precise thermal regulation within Carrier, Bryant, and Payne gas furnaces. This L155-55F limit control features a fixed temperature setting that opens the circuit at 155°F and automatically resets once the temperature drops by 55°F. Engineered to prevent heat exchanger overheating, this OEM replacement part ensures the system stays within safe operational parameters, protecting both the equipment and the structure from hazardous high-limit excursions. As a furnace high limit switch, the HH18HA454 is frequently utilized in Bryant 350MAV and various Carrier gas furnace troubleshooting scenarios where the blower motor fails to deactivate or the burners shut down prematurely. Resistance to vibration and rapid thermal response times make this L155-55F switch a reliable choice for maintaining HVAC system safety and preventing furnace limit switch tripping during peak heating cycles.

• Precise Thermal Calibration: Fixed 155°F cutout with a 55°F differential ensures accurate cycle management and prevents nuisance tripping.
• OEM Compatibility: Exact Carrier HH18HA454 specifications guarantee a drop-in fit for specific Carrier and Bryant furnace models.
• Safety Compliance: Protects the furnace heat exchanger by interrupting power to the gas valve if airflow is restricted or temperatures exceed safe limits.
• Durable Construction: Built to withstand the high-temperature environment of the furnace plenum without drift in setpoint accuracy.

What causes a Carrier HH18HA454 limit switch to trip repeatedly?
Repeated tripping usually indicates restricted airflow, such as a clogged filter, blocked return air, or a failing blower motor, causing the plenum temperature to exceed the 155°F threshold.

Can the L155-55F be used as a universal replacement?
While the L155-55F rating describes the temperature profile, specifically using the HH18HA454 ensures correct mounting orientation and terminal positioning required for Carrier OEM furnace cabinets.

How do I verify if this limit switch is faulty?
Using a multimeter, technicians should check for continuity across the terminals. If the switch is open at room temperature, the internal bimetal disc or contact points have likely failed, requiring a replacement.

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.