Carrier HH18HA199 Limit Switch 322838-753 This internal pilot-operated valve is

This internal pilot-operated valve is a critical component for safety and efficiency in HVACR and commercial combustion systems

Always verify your wiring diagram for phase-to-phase compatibility

check for a dirty furnace filter

For technicians troubleshooting a Carrier Error Code 31

SC12MLX-115V

Carrier HH18HA199 Limit Switch 322838-753 This internal pilot-operated valve isThe Carrier HH18HA199 Limit Switch is a critical safety component designed for high temperature monitoring in HVAC induction combustion furnaces and residential heating systems. This genuine OEM replacement part is calibrated to trigger at a fixed 200 degree opening temperature, automatically interrupting the electrical circuit via its SPST (Single Pole Single Throw) configuration to prevent heat exchanger damage or hazardous rollout conditions.