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Circuit/System Description

WARNING: This page is about a different car, the 2019 Buick Cascada, 2018 Buick Cascada, and 2017 Buick Cascada. However, it is still accessible from the selected car via links, so may be relevant.

The HVAC control module uses an air quality sensor to detect hydrocarbons. This sensor operates using an ignition voltage circuit, a ground circuit and a signal circuit.

This information is sent to the HVAC control module using a pulse width modulated (PWM) signal. It is used only when the automatic HVAC mode is requested by the customer.

When the HVAC module detects the concentration of pollutants exceeds a preset value, recirculation mode is commanded to keep the passenger compartment free of pollutants.

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