What is the purpose of the test furnace pressure switch and how does it contribute to the overall functionality of the furnace system?

The purpose of the test furnace pressure switch is to ensure that there is proper airflow in the furnace system. It contributes to the overall functionality by detecting if there is enough air pressure for the furnace to operate safely and efficiently. If the pressure is too low, the switch will prevent the furnace from turning on, preventing potential safety hazards.