What happens when the limit switch of a gas furnace is triggered?

When the limit switch of a gas furnace is triggered, the correct outcome is that the furnace shuts down to prevent overheating. The limit switch is a safety device designed to monitor the temperature within the furnace. If the temperature exceeds the safe operating limit, it will cut off the burner, stopping the operation of the furnace to avoid damage or hazardous conditions, such as overheating or even potential fires. This functionality is essential in maintaining the safe operation of the heating system and protecting both the equipment and the home.

The other options do not accurately represent the role of the limit switch in this context. For example, the furnace continuing to operate would defeat the purpose of the limit switch, which is designed specifically to interrupt operation during unsafe temperature levels. Similarly, while the pilot light being extinguished or the air conditioner starting up are processes that may occur in different scenarios, they are not the direct consequences of the limit switch being activated.