This isn't a complaint but rather an observation.

I have the basic heater controls with a push button vent selector between the fan and heat blend *****.

The past few mornings it's been cold enough to have the vent selector on 'dash' and 'floor', heat blend all the way to 'hot' (red) and fan on full (4).

What I have noticed is that the sound of the airflow by the passenger floor changes based on vehicle speed. When going below 30mph it's loud - similar to "max a/c" or recirculate. Above 30mph it gradually goes away.

I can make it get loud again by selecting recirculate - sounds exactly the same - or if I select the recirculate button when below 30mph there is no sound change.

I suspect it's a software fix to boost heating efficiency at low speed... but what do I know.

What I know it isn't - is a vacuum leak or the like. The blend doors and vent selects are electric motors in this generation. It almost has to be by design.

Can anyone else verify this behavior? I'm strictly curios - tried to give as much detail as I can on how to re-create it.

Of course, be careful when driving and experimenting - don't get distracted.

Jon

 

Mine has the automatic control and I haven't noticed that yet, BUT I've had two other vehicles in the past that would automatically switch either when sitting still or at low speeds so you wouldn't have to inhale other people's exhaust fumes at low speeds or while stopped in traffic.

My last car was a Pontiac G8 GT and it had what was called "Pollution Mode" and you could turn that feature on and off, but it was a pretty cool thing to have especially in traffic.

 

I've noticed a change in the sound as you describe. I had not attempted to figure out what it was though. Sinse you mentioned it though, that is what it sounds like.

 

mine does it when the engine is cold .... i would think it helps warming the cab up a little faster... my hvac is manual also