HH18HA502 Automatic Reset Disc Limit Switch - 180°F Open, 140°F Close | Compatible with Carrier, Bryant, Payne HVAC Systems

The HH18HA502 is a temperature-sensitive disc limit switch designed to protect compatible HVAC systems from overheating, supporting reliable operation through precise temperature monitoring. How It Works： This bimetallic disc switch remains normally closed during regular operation, allowing power flow to critical components. When system temperatures rise to 180°F, it automatically opens to cut off power, preventing heat-related damage. As temperatures drop to 140°F, the switch closes again to restore normal functionality—no manual intervention required, ensuring continuous system protection. When to Replace： Consider replacement if the switch fails to open at 180°F (allowing overheating) or fails to close at 140°F (restricting operation). A faulty limit switch may compromise system safety or cause inefficient performance. Installation Guidelines： For safe installation, always disconnect all power sources to the HVAC unit before servicing. Follow your system’s owner’s manual for wiring instructions, ensuring proper mounting to maintain temperature sensitivity. Professional installation by a certified HVAC technician is recommended to adhere to safety protocols. The HH18HA502 limit switch is engineered to meet the operational needs of compatible systems, focusing on reliable overheat protection and automatic recovery to support long-term HVAC efficiency. Verify your unit’s model and part number in the owner’s manual to confirm compatibility.

• Core Temperature Specifications：This disc-style limit switch is normally closed, opening on temperature rise at 180°F and closing on temperature drop at 140°F. Features SPST (Single Pole Single Throw) configuration with automatic reset functionality
• Safety Protection Function：Activates by opening at 180°F to interrupt power flow during excessive heat, preventing HVAC component damage. Automatically closes at 140°F to restore operation once temperatures normalize
• Broad Compatibility：Designed for use with select Carrier, Bryant, and Payne HVAC models. Consult your unit’s owner’s manual to confirm part number compatibility
• Direct Replacement Part：Replaces obsolete part numbers. Engineered for seamless fit in compatible systems without modifications
• Installation Safety Note：Always disconnect power to the HVAC system before replacement. Professional installation by a certified technician is recommended to ensure proper wiring and alignment