dAveSPEC

How is it when the A/C system is off and the sunroof is up that air is distributed out of the vents? Even with the system off the vents still put out a minute amount of air. For some reason, which I can't explain, this circulation of air has me dumbfounded. Although the air is still outside air, the circulation with just the sunroof cracked is better than I would have originally thought possible. Its nice to have a break from stale air.

P.S. I'm coming from a Chevy P/U...never seen this before.

NFLblitze1

lol wha? never seen this before?

03CoupeV6

Haha just hit the recirc button if you want it to stop, or enjoy the circulation of air in the cabin!

MichiganRich

Pretty common actually. Most modern cars are built so tightly that there is a designed-in amount of positive airflow in the car even with the climate control off. All my Hondas have done it and the '04 TL is no exception. In my '98 Accord, if I recall correctly, it was limited to the main vent in the center of the dash.

caball88

just simple physics, when you recirculate option is off the air passes through the vents. if a window is open it allows the air to travel through so there is a constant air flow. try blowing into a straw with the other end plugged, you won't get far. but let go the other end of the straw and the air will stream through.

ayethetiense

creates a vacuum

caball88

basically summarizes what i said...hehehe

KJSmitty

I thought this was actually mandated federally some time ago.... In order to help alleviate the chance of a carbon monoxide issue the system had to circulate "some" fresh air when in the off position.
Not positive but I'm pretty sure I remember reading that back in my "dealership" days...

Cheers

Sherlock

cars aren't built that tightly, there are vents either in the back dash, the C-pillar, or under the rear seat front edges that allow cabin pressure to regulate. If there weren't, and the hvac were not on recirc, wouldn't you think the pressure would build up and the vents wouldn't blow ? On Recirc it draws and blows inside.

But to the point, with the fan off, and anything open, sure, it's an open pipe from where the hvac gets it's intake, thru a stalled fan, and out the vents, just a big long open tube at that point, only baffeled by our micron filters in the dash.

PeterUbers

iTrader: (1)

I just learned today that the memory settings for the seats also saves the A/C settings ... that's pretty impressive.

rickneuropa

Here is another reason for this......anyone ridden in a Highlander, and drove with the back windows down? There is this suction that happens, that hurts your ears, and has this drone to it that is excrutiating!!! That car is too sealed. I believe that Honda does this type of vents open to disallow the moonroof from causing this unwanted suction noise from happening.

EpiK

My wife drives a Montero Sport, and it does the same thing. We can't have the kids roll down the windows in the back without a window upfront cracked or the pressure is actually painful...

1995hoo

To the original poster, if this bugs you, try flipping the knobs under the two outboard vents to the "closed" position. The air you describe will be forced out the top vents instead--it'll still come through, but it'll be less noticeable.

mark 3M bra man

It seems most foreign cars have it and american cars don't. At least from my experience.

SilverQuartzTL

The reason this happens is because the frequency at which the air vortecies are pealing away from the outside of the car (turbulent air flow) match the natural frequency of the volume of air inside the car. If you open another window, this shouldn't happen. Sealing "too tight" is close but not quite right.

All cars manufactured now have vents toward the back of the car. They're one way valves, they allow air to exit the cabin, but won't let air in. The inlet is the heating ventilation and air conditioning system (HVAC). The intake for automotive HVAC systems since the 60s has been the cowl, the area between the hood and front windshield. By the nature of the design of the vehicle, positive air pressure is experienced here forcing air through the HVAC system, out the vents and eventually out the one way valve in back.

Anyone remember cowl induction?? It's was essentially dubbed a "free" supercharger. Properly located, at speed it provides positive pressure, forcing more air into the engine. Worked pretty well when properly designed.

Anyone else have a friend try to rig up their own "cowl induction" with an intake near the front of the hood? Placed here, there is actually negative gage pressure which means it's more difficult for the engine to suck in air... Result was decreased performance HAHA!!!

ElmerHiggins

Nope, heres what really happens in the TL.
If you have a fan speed above minimum set while the climate controls are activated, the car will continue to run the fan at a slower speed when you turn off the climate control. You can however get the car to stop running its fan by turning the fan to the minimum setting before turning off the climate control. The car will then not blow any air at you at this point.

Sherlock

SilverQuartzTL.. OOOooooo.. 10 points.

And anyone want to duplicate the howl in the TL ?? climate on auto, all windows closed, open driver's side rear window half way and hit highway speeds.. man that hurts. My dad's '77 corvette stingray used to do it horribly.

SilverQuartzTL

Uhh... no. If you press off, fan goes off. Pretty simple. Try it when you're not cruising down the road, just chillin in the driveway. Off turns off the fan, I just tried it to confirm. However, when you're cruising down the road, since there's still positive pressure on the inlet of the HVAC system air still forces its way past the fan blades.

ElmerHiggins

I believe the original poster of this thread was speaking of the fan continuing to blow even though all climate control is turned off. If you have the fan on full blast and then turn off the climate control, the fan still blows noticably, however, if you turn the fan to the minimum it can go while climate control is on and you then turn climate control off, it does not blow (or it blows too slow to tell).

dAveSPEC

Actually, I was talking about air flowing through the vents with the system, fan everything off. I don't believe the fan still blows when the system is off...Either way I like the fact that air is circulated when I press the off button, as I said it is a fascinating little feature that I have never had prior to the TL. Thanks for the insight everyone!!!

SilverQuartzTL

Off means fan is off period. For an explanation of why air continues to flow through vents, please read post 15, paragraph 2

dAveSPEC

Thanks SQ!

bluenoise

The fan being off doesn't mean air can't be pushed through anyway. Also, if your moonroof is open in tilt mode, the air rushing over the roofline creates a lower pressure and sucks interior air right out. This can be useful if any "undesired aromas" enter the cabin.

Dafried

Hi PeterUbers - just FYI, radio presets/sound fields/and mirrors are all saved as well. Anybody know of other settings I missed?

ElmerHiggins

My TL blows air at slow speed even with climate control totally off if the last fan speed when climate control was on was anythign higher than minimum. There may be something wrong with it now that I think if it.

mp3car

this also explains why in almost all situations, the reason the fan speed changes when you put it on rec mode, is b/c the fan is not having to "pressurize" the car (even with vents/leaks, it still has 'resistance' bringing air into the cabin, at least in contrast to my next statement)... Picture this... take a fan, such as a computer fan, and block the front or back, so it isn't moving any air through it, the RPMs of the fan will go up b/c almost all the load is off of it. A similar situation happens when you hit rec, the fan is just moving air in the cabin, and not having to bring air into the cabin, just moving the air already there... theoretically, if it was COMPLETELY sealed, there would be very little, or no air coming in the car when it was on "fresh" setting...