Random Blast of Air At Highway Speeds

[Phimosis]

Sounds weird, I know. This has been an issue repetitive enough to post and see if anyone else is experiencing this.

So, I'll driving along on the highway averaging between 75-80 mph. The a/c is on low with the fan speed typically on one, maybe two. And then, out of nowhere, I get this massive burst of air coming through the vents. It's as if someone turned up the fan speed to max. It does it without warning and for no rhyme or reason. My '22 Maverick and my mom's '23 Bronco Sport did the same thing. It's only at highway speeds.

It'll last for a couple of minutes and then go away on its own. It's the strangest thing. I mean, it's not so much a bad thing. It could be worse. It could turn off completely and quickly into a sweatbox but at least, in this case, it's just random bursts of air.

Has anyone else had this issue? If so, is there a diagnosis for it? Maybe there's a reason it does it. I don't know. All I can say is I've had a car that did this.

I’ve never noticed this, but my best guess is that it is the damper on the fresh air exchanger.

All HVAC systems have a certain number of fresh air cycles per hour to make sure that if your house is extremely well sealed, that you don’t suffocate from C02 build up and lack of oxygen.

In cars, fresh air exchanges are even more important, as you’re sitting one foot away from a prolific carbon monoxide source: any exhaust getting into a sealed cabin could be deadly.

When the damper on the fresh air exchanger opens, the pressure gradient at the base of your windshield, where the air intake is, forces fresh air into the cab. The faster your velocity, the higher the pressure gradient and more noise it will make.

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[SRQ]

I had this with my '23 and now with my '24, also. Dealer cannot "replicate".
I do not use Auto.
First time it happened, I thought my wife bumped the fan switch. It got so loud, so fast. Like fan was turned to high speed for some useless reason. We had been driving highway speed for hours. But, it was not hot or humid in Mackinac City, MI in May.
Been confused by it ever since.

 

[The Real Maverick]

I’ve never noticed this, but my best guess is that it is the damper on the fresh air exchanger.

All HVAC systems have a certain number of fresh air cycles per hour to make sure that if your house is extremely well sealed, that you don’t suffocate from C02 build up and lack of oxygen.

In cars, fresh air exchanges are even more important, as you’re sitting one foot away from a prolific carbon monoxide source: any exhaust getting into a sealed cabin could be deadly.

When the damper on the fresh air exchanger opens, the pressure gradient at the base of your windshield, where the air intake is, forces fresh air into the cab. The faster your velocity, the higher the pressure gradient and more noise it will make.

Pretty much so. Except the oxygen part.
You really can't run out of oxygen in a house or car. But yes, pollutants (and CO falls into that category) can build up.

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