Air inlets into vehicle?

[psartman]

I'm working on an SUV build and plan to install fans to vent out a screened sunroof. I know that you can't push air out unless there is a way for fresh air to come in. There may be times I'd want the windows closed for stealth or security. Does anyone know if fresh air can enter a vehicle through the filtered cabin air intake when the vehicle is off? Are there settings on the vehicle HVAC controls that allow this- for instance if I make sure the recirculation control is set to fresh air, will this make a difference when the SUV is turned off?

 

[highdesertranger]

Hmmm Good questions. I know some vehicles with electronic controlled vent doors reset to closed when the key is turned off. Also some vacuum controlled doors do this. Of course manual controlled doors do not reset they stay wherever to control is left.

So I what type of climate control system do you have? Electronic, Vacuum, or Manual?

Highdesertranger

 

[bullfrog]

Most older vehicles rubber door and window seals leak air as well, using rain deflectors and opening the window slightly isn't much of a security issue in my opinion. I can always move the old license plate from over the rust hole in the floorboard if I need more air! Lol!!!

 

[Scott3569]

Very good questions, I can give you the answers that I came up with, However we have different vehicles..
And I also have ripped out my interior..

06 grand caravan. with a rear heating and cooling(removed)

once the rear heater was removed, there was an open hole in the floor, I am using this Combine with 4 high velocity Computer case fans(built a duct systems for fresh air)

to exhaust, I will just use a usb fan or two out the front windows, possibly out of one of my rear side windows, that has yet to be completed in my build..

?Surprisingly the 4 computer case fans push a lot of air, and are virtually silent

 

[Axel]

I cut a hole in the floor of my van as an air intake for the solid fuel heater, and covered the hole with a HVAC floor register and bug screen. It doubles as an air intake in the summer for my swamp cooler, and when parked with the roof vents open convection moves air in from the floor vent and out of the roof vents. Stays noticeably cooler inside than a typical car parked in the sun.

 

[kklowell]

I'd worry about CO coming in through a hole in the floor...not an issue?

 

[maki2]

If you want to put a hole in the floor and have it watertight when not in use do a search for a "screw in deck plate".

They are used in boats so get them from a marine supply source or order online. They come in different diameters. You install the fitting through the floor and the cover plate is in your interior. Looks nice and professional...because it is.
.

 

[crofter]

Maxxfan in the roof and installed screen vent in the side.
-crofter

 

[Axel]

I'd worry about CO coming in through a hole in the floor...not an issue?

Never an issue. I close the floor vent while driving, and even when I forget the CO alarm has never gone off.

 

[kklowell]

Good to know, thanks.

 

[MGfromBC]

If your vehicle has a cabin air filter, take a look at the air intake above it that probably goes to an opening roughly under your wipers. Looking for it or at it may require a flashlight and a mirror.

MG

 

[tx2sturgis]

Almost all modern passenger vehicles have an air exit somewhere in the cabin. It will often look like a heater duct or vent, located in a door jamb, the trunk area, along the rear hatch pillar in an SUV or crossover, or a well hidden vent or several small openings on the back of a van or a pickup cab. 

This is done to keep air moving when you turn on the HVAC or powered ventilation. 

Sometimes these vents have rubber 'flappers' on them to keep out rain, or to keep them from being able to 'inhale' air from the rear exhaust area of the vehicle. Some vehicles even keep the dash heat/AC blower running on very low speed even when you turn the blower completely off. This is done to keep the cabin air moving from front to rear and not the other way around when the windows are all closed and you're sitting in traffic idling.

Now, if you intend to inhale air thru the exit vent, the flappers might prevent that...you just have to find the vent if there is one, and look it over, maybe with a small LED or penlight, then do some testing.

At any rate, the exit vent is not usually designed to handle large volumes of intake air but it might be able to supplement the primary air intake system when the vehicle is shut down and parked.