Carrier HH18HV145 Limit Switch

The Carrier HH18HV145 is a high-precision HVAC auto limit switch engineered to maintain safe operating temperatures within gas and electric furnaces. Operating with a 115-145F temperature range, this genuine OEM replacement part acts as a critical safety barrier, automatically interrupting the circuit to the burners or heating elements if the supply plenum exceeds the 145°F threshold. This auto-reset limit switch is designed for demanding industrial and commercial HVAC environments, featuring a rugged SPDT (Single Pole Double Throw) configuration. With a robust current rating of 15A at 120VAC and 10A at 240VAC, it ensures reliable electrical performance. The HH18HV145 is highly compatible with several Carrier, Bryant, and Payne models, including the 48HJD series, providing a direct-fit solution for technicians troubleshooting furnace short-cycling and overheating protection issues. Its durable housing is built to withstand dust and moisture, ensuring consistent temperature control and system longevity in professional mechanical applications.

• Precise Safety Control: Automatically shuts down heat sources at 145°F to prevent heat exchanger damage and system failure.
• Auto-Reset Functionality: Restores power to the system once the internal temperature drops below 115°F, minimizing manual intervention.
• OEM Compatibility: Exact replacement for Carrier HH18HV145, ensuring seamless integration with existing terminal connections and mounting brackets.
• Heavy-Duty Electrical Rating: Capable of handling 15A at 120VAC, making it suitable for both residential and light commercial equipment.
• Rugged Construction: Designed to resist environmental factors like moisture and dust, maintaining terminal integrity over time.

What causes a Carrier furnace limit switch to trip repeatedly?
Frequent tripping is usually caused by restricted airflow from a clogged 1-inch or media filter, a failing blower motor, or blocked return air vents, causing internal temperatures to spike.

How do I test the HH18HV145 for continuity?
After disconnecting power, use a digital multimeter set to the Ohms or Continuity setting. At room temperature, the switch should show continuity (closed loop); if it shows an open circuit while cool, the internal contacts have failed.

Is this switch compatible with my specific Carrier unit?
This switch is a standard 115-145F auto limit used extensively in the 48HJD024 and 100YA series. Always verify the temperature stamping on your existing switch before installation.

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.