Carrier HH18HA440 Limit Switch

The Carrier HH18HA440 is a high-performance Auto Limit Switch designed for precise thermal protection in residential and light commercial HVAC equipment. Built for high-reliability applications, this OEM Carrier part functions as a critical safety component by monitoring internal plenum temperatures. It is engineered with a set 140-degree Fahrenheit open temperature and a 100-degree Fahrenheit close temperature, ensuring your system initiates a safety lockout or blower cycle to prevent heat exchanger damage during restricted airflow conditions. This limit switch is a direct replacement for many Carrier and Bryant package units and furnaces, featuring an automatic reset capability that restores circuit continuity once temperatures drop back to the 100°F threshold. Its robust construction resists the mechanical wear associated with frequent cycling, making it the preferred choice for licensed HVAC contractors performing furnace troubleshooting or preventative maintenance to resolve common HVAC error codes related to overheating.

• Precise Thermal Control: Factory calibrated to open at 140°F and close at 100°F for consistent furnace safety.
• Automatic Reset: Eliminates the need for manual intervention by automatically resetting once the HVAC system cools.
• OEM Compatibility: Genuine Carrier replacement part ensuring exact fit and manufacturer-spec performance in Carrier and Bryant units.
• Enhanced System Longevity: Protects the heat exchanger from permanent deformation caused by chronic overheating.
• Durable Construction: Designed to withstand the high-temperature environments of gas-fired and electric heating sections.

• How do I know if my Carrier HH18HA440 needs replacement? A technician will typically find the switch open (no continuity) even when the furnace is cool, or the system may exhibit short cycling with error code 33.
• What causes this limit switch to trip frequently? Common causes include clogged air filters, restricted return ductwork, a failing blower motor, or a dirty evaporator coil, all of which reduce necessary airflow.
• Can I use this switch in a Bryant or Payne unit? Yes, since Carrier produces parts for the entire brand family, the HH18HA440 is cross-compatible with various Bryant and Payne HVAC models requiring a 140-40F limit.

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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.