Auxiliary Air Valve (Idle Speed): Description and Operation

Fig. 20 Air regulator:

The air regulator, Fig. 20, bypasses the throttle valve to control the quantity of air for increasing the engine idling speed when starting the engine at an underhood temperature of below 176°F.
A bi-metal and a heater are incorporated into the air regulator. When the ignition switch is turned to the ``Start'' position or when the engine is running, electric current flows through the heater, and the bi-metal, as it is heated by the heater, begins to move and closes the air passage in a few minutes. The air passage remains closed until the engine is stopped and the underhood air temperature drops below 176°F.