Carrier HH18HA150 Limit Switch

The Carrier HH18HA150 150F Limit Switch is a critical OEM safety component engineered for precise thermal monitoring in HVAC furnaces and residential air handlers. As a veteran-grade L150-40F limit control, this switch is designed to open on rise when the heat exchanger reaches a threshold of 150F, effectively interrupting the burner circuit to prevent thermal stress or equipment damage. It features an automatic reset mechanism that closes once temperatures drop by 40F (approximately 110F), ensuring the system returns to normal operation without manual intervention. Built with a rugged IP66-rated housing, this disc-type temperature actuated switch provides high-precision contact performance and protection against dust and moisture. This factory authorized part is the standard replacement limit switch for various Carrier, Bryant, and Payne systems, offering a panel mount design and 0.5A 30V rating for seamless integration into process control circuits.

• OEM Compatibility: Guaranteed fit for Carrier-family equipment, maintaining original high-limit switch factory specifications.
• Reliable Thermal Protection: The L150-40F rating ensures the unit trips exactly at 150F to safeguard the heat exchanger.
• Superior Build: Features an IP66 protection rating for durability in demanding mechanical environments.
• Automatic Reset: Eliminates downtime by resetting the circuit once safe operating temperatures are restored.

Common Questions

What causes a Carrier HH18HA150 limit switch to trip?
Frequent tripping usually indicates restricted airflow, often caused by a dirty air filter, blocked return ducts, or a failing blower motor causing the heat exchanger to overheat.

Can I test this limit switch with a multimeter?
Yes. At room temperature, the HH18HA150 should show continuity (NC position). If the switch is open while cool, the internal contacts have likely failed and the part requires replacement.

Is this a universal furnace part?
While limit switches are common, this specific OEM part is calibrated to a 150F setpoint. Always verify the L-rating on your existing bracket to ensure it matches the 150F/40F differential required for your furnace model.

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.