Q: When A/C unit is off, vents still have air flow

asked by on August 08, 2016

While driving my car, I have noticed that when the A/C is off, the vents still have some air flowing from them. Also, while the A/C is “Off” and I turn the temperature knob to Cold, then the air comes out cold (but the A/C unit is “Off”). Just for your info, this also happens with the heater - but it is summer here right now.

When I’m in a stopped position, it doesn’t do it. It only happens while driving and I especially notice it when I’m on the interstate. I called the dealership and they said this is normal for the purposes of ventilation. Do you agree with them and is there any way to prevent the constant air flow?

This type of ventilation is typical on most cars. Try setting the controls to "Recirculate" mode and see if that helps. The Recirculation setting typically closes off the flow of outside air from entering the passenger compartment. At highway speeds, there usually is enough ram air flow, even with the fan off, to feel some airflow into the passenger compartment. It is also possible that you may be experiencing a GM strategy to always have some fresh airflow into the cabin.

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