Auxiliary Air Regulator
The auxiliary air regulator provides additional air required to aid in cold engine starting and initial warm-up. The valve consists of an electrically heated bi-metal-strip, movable disc and air by-pass channel. The bi-metal strip is wrapped with a heater coil which is energized by the fuel pump relay. Control of the bi-metal plate is done by engine coolant temperature (except Datsun models). The air by-pass channel is open when engine is cold and closes gradually as temperature rises. At predetermined temperatures, air by-pass channel is blocked and additional air flow stops. See Fig 1.
NOTE:
Control of Datsun auxiliary air regulator is by monitoring engine oil pressure and alternator output. For more information see "Air Flow Meter" in this article.