# Weak HVAC airflow in fresh air mode with fan off



## Ursa (Jun 27, 2017)

Since new, my car has had very weak HVAC airflow in fresh air mode with the fan off. With the dash vents on, you can barely feel any air coming in at all. It goes away completely when you hit the recirc button, so the flapper doors seem to be moving. 

Not a big deal; was just wondering if this was normal for the Cruze. I did search the forum and didn't come with much; will check the flapper door operation once I get the car back from its transmission replacement.


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## pontiacgt (Jan 12, 2011)

your not going to get a lot of air flow unless your moving and have a window slightly open or if you have a sunroof and its on vent. You need a vacuum type of effect to get the air to flow. On the older cars when the fan was off they still turned some on the new cars they no longer do that.


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## NickD (Dec 10, 2011)

30 Olds, could crack open the bottom of the windshield, later 30's-50's had a vent on the crowl under the windshield that could be opened, practically all vehicles had side vent windows that could even be opened in a rain storm to get air. Really miss these.

Now all vehicles have a grille under the windshield, air flowing over the hood upwards over the windshield creates a venturi effect that creates a vacuum in your vehicle so not only getting air, getting it sucked out. So would have to say getting no air with the blower switched off is normal.

The way cars are designed today, can't even drive them with a defective blower motor, windows fog up and they want a small fortune for these things. Cruze motor draws 20 amperes at full speed, can no longer get by with a 20 ampere generator.

Ha, a brief story of my life designing alternators, first 30, than 60, now over a 100 ampere output. Marketing demanded lower manufacturing cost for each successive model. FWD was a nightmare, an extra 40 amps for that radiator fan. Talk about burning the midnight oil to keep your job.


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## jblackburn (Apr 14, 2012)

Yeah, it's normal. The air is HOT too when it's not really that hot outside.


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## Ursa (Jun 27, 2017)

jblackburn said:


> Yeah, it's normal. The air is HOT too when it's not really that hot outside.


If the car is not moving for any length of time, the engine bay heats up pronto...and the cowl intake draws the heat right into the car. Best to hit the Recirc button and/or turn on the A/C if traffic isn't moving.

Seems to me that the Ford and GM cars from the '70s and '80s tended to have more effective ventilation than what we have today--back when A/C wasn't on every car, and there wasn't a cabin air filter plugging up the works. The '81 Escort I had delivered a veritable gale of air through its dash vents when the car was up to speed, and there was no fan in that part of the system to help move the air.


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## ChevyGuy (Dec 13, 2014)

Ursa said:


> Seems to me that the Ford and GM cars from the '70s and '80s tended to have more effective ventilation than what we have today


It's probably due to aerodynamics. The pressure wave that would push air though the vents is reduced. Frankly, I don't expect to get much of anything though the vents if the fan is off - regardless of the make/model/year.


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## Ursa (Jun 27, 2017)

ChevyGuy said:


> It's probably due to aerodynamics. The pressure wave that would push air though the vents is reduced. Frankly, I don't expect to get much of anything though the vents if the fan is off - regardless of the make/model/year.


I guess I never considered aerodynamics. Now that you mention it, the older cars I was thinking of that did deliver a lot of ventilation simply via ram air though the cowl weren't very aerodynamic. My old Escort, Reliant, and Toyota trucks all had great ventilation, but also had the aerodynamics of a brick compared to today's cars.

Still, the Cruze has cowl air intakes that are tiny compared to every other car I've owned and that makes me wonder if airflow suffers as a result. One has to crank the fan up to 3 or 4 to keep the car comfortable on a 60 degree F day with the A/C off.

All in all, not a big deal. Glad I have A/C. Driving a Cruze with the rear windows lowered is miserable!


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## jblackburn (Apr 14, 2012)

As I recall, it's slightly tucked up under the hood lip in Cruzes too, so probably not a whole lot of air even gets forced in there. Yeah, my 1988 Honda had fantastic flow-through, which was good because at the age I owned it, the A/C was dead, but it was shaped like a wedge.

I miss wing windows. Our 70's BMW had those as a kid, and they were incredible.



> All in all, not a big deal. Glad I have A/C. Driving a Cruze with the rear windows lowered is miserable!


That buffeting noise? I've had others that do that, haha. Also a function of aerodynamics.


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