2. The air cleaner is equipped with an air valve installed inside the duct that regulates the temperature of the incoming air, which enters the carburetor through the fresh air supply duct, the heater housing and the air duct, or through both routes (see illustration).
4.2. Heated Air Intake (HAI) System: When the engine is cold, a temperature sensor allows vacuum from the intake manifold to flow into the vacuum actuator, which opens the air valve, allowing hot air to flow into the air cleaner through the heater housing and air duct
3. The air valve is actuated by a vacuum actuator. The temperature sensor in the air filter controls the vacuum supply from the intake manifold to the vacuum actuator. When the incoming air temperature is below 30°C, the temperature sensor opens the vacuum supply from the intake manifold to the vacuum actuator. In this case, the air valve rises and allows hot air to pass through the heater housing and the air duct; when the incoming air temperature is above 45°C, the temperature sensor does not allow vacuum to enter the vacuum actuator and the air valve remains down. In this case, cold air passes through the fresh air duct. When the incoming air temperature is between 30 and 45°C, the air valve is in a partially open position and the incoming air is a mixture of air passing through both routes.
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