Furnace Limit Switch 10123538SP

About the Limit Switch

The flame rollout limit switch monitors the heat surrounding the burners. If the inducer fan motor cannot draw enough air through the burners, or if the furnace is not venting properly, the rollout limit switch will open to halt the ignition sequence and prevent the furnace from heating. When this happens, the furnace will shut off after running for a few minutes. To determine if the flame rollout limit switch is defective, use a multimeter to test it for continuity. If the switch does not have continuity, replace it. Be aware that poor airflow through the burner is often a result of insufficient ventilation or a restricted exhaust vent. Make sure that your furnace is in a properly ventilated location and the exhaust vent is clear of obstructions.