Carrier HH18HA130 Limit Switch 319852-301 If your system requires modulation

If your system requires modulation

including GCS16 and LCH series

swapping in this Heil Quaker furnace part is the standard professional fix

providing a fail-safe "normally open" state that prevents complete airflow blockage during a power loss

it utilizes a diaphragm-isolated spring chamber to prevent water contact with the spring

Carrier HH18HA130 Limit Switch 319852-301 If your system requires modulationThe Carrier HH18HA130 is a high precision, OEM auto limit switch designed for critical thermal regulation within residential and light commercial HVAC systems. This disc type temperature actuated switch features a specific operating range of 100 130F, functioning as a primary safety mechanism to prevent heat exchanger damage and ensure efficient blower motor cycling. As a direct replacement for the HH18HA130B, this component maintains strict 1 2" NPT