Rick's Free Auto Repair Advice

Active Grille Shutter

How does the Active Grille Shutter work?

Purpose of the active grille shutter

The active grille shutter assembly accomplishes three things: 1) Improves aerodynamic efficiency at higher speeds by forcing airflow over the hood, 2) Improves emissions by blocking airflow across the radiator at cold startup to speed up engine warmup, and 3) increasing passenger comfort by blocking airflow across radiator to improve coolant heat retention.

As carmakers downsized engines to improve fuel economy they ran into a problem with cabin heat. Smaller engines require less coolant, so in cold weather that coolant cooling couldn’t provide enough heat to warm cabin occupants and keep the engine at full operating temperature. To remedy the situation, car makers install an active grille shutter assembly in front of the radiator to reduce airflow and increase coolant heat retention.

active grille shutter

When the active grille shutter operates

The ECU controls the active grille shutter operation. It closes the shutter when it detects low cooling and A/C loads the engine cooling system doesn’t need high airflow. In some makes, the shutter is controlled by the fuel pump control module. In other words, high fuel pump loads automatically dictate high speed and that opens the shutters.

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

©, 2019 Rick Muscoplat

Posted on by Rick Muscoplat



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