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What is an active grille shutter and why do cars need one?

What is an active grille shutter?

What does it do and why do cars need them now when they never had them before?

Purpose of the active grille shutter

The active grille shutter assembly accomplishes three things:

An active grille shutter improves aerodynamic efficiency at higher speeds. When it closes, it blocks airflow through the grille and radiator and forces airflow across the up and across the hood. Without the shutter, air rams into the engine compartment and can’t easily escape, so it forms a cloud of air in front of the vehicle that disturbs aerodynamic airflow.

The active grille shutter helps the engine heat up faster to reduce emissions

The shutter is closed on cold startup to prevent cold air from reducing the temperature of the coolant in the radiator and by stopping the flow of cold air around the engine, so it warms up faster.

An active shutter helps improve cabin heating

Stopping the flow of cold air across the radiator keeps the coolant at a higher temperature so it can heat the cabin more efficiently. Why is this needed now? Because late model engines are much smaller and hold less coolant. Cold airflow across the radiator could chill the coolant to the point where cabin heat would be lukewarm.


active grille shutter

When the active grille shutter operates

The ECU controls the active grille shutter operation.

The ECU opens the grille shutter at low speeds or when the engine temperature rises and needs requires additional cooling. That allows enough airflow to chill the coolant enough to remove engine heat.

The ECU closes the grille shutter as the vehicle’s speed increases to reduce drag and increase aerodynamic airflow across the hood.

Although the closed shutter reduces the amount of air going through the radiator the increased airflow efficiency across the hood and the associated increase in MPG is more important. The radiator fan can pull heat out of the radiator if the engine needs moderate cooling.

The ECU commands a partial opening to regulate airflow through the radiator to keep engine temperature at the right level.

The shutters remain closed at engine startup and in cold weather.

©, 2019 Rick Muscoplat

Posted on by Rick Muscoplat

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