American Volt 185 Degree Engine Thermostat Temp Sensor Switch 3/8" Npt Radiator Cooling Fan 185'F automotive engine grounding fan switch. 3/8" NPT brass thread-in temperature probe. Activates fan at 185 degrees and turns off at 170 degrees. Universal fit for any application with a 3/8" NPT port. Threads into engine block, radiator, manifold or water outlet.