Early Fuel Evaporation Thermal Vacuum Switch (EFE-TVS)

When engine coolant temperature is below the calibration point of the switch, manifold vacuum flows through ports 2 and 3 of this switch to the EFE actuator, closing the EFE actuator. Above the switching point, port 3 of this switch is blocked and the EFE vacuum actuator is vented to atmosphere through port 1.