filmteknik

Can't blow air in unless there is a place for air to escape. So how does air escape the passenger compartment. I see some small grills in back on each side of the cargo area (just under where the privacy shield slides). I'm guessing that's it. Where do they lead?

Steve

satz

I believe the air does vent through those grilles in the boot. They would just go into the body cavity and then out the gaps in the body...somewhere at the back!

As an aside, if you put the AC into recirc, then those vents remain open, but the difference is that vents near the AC close, so that air from within the cabin is sucked back into the AC intake, rather than fresh air being sucked in from the vents under the bonnet.

cheers

Satz

tfischer

Well, when some air escapes from me, it does not escape from the car until I roll down a window. I can supply you with affidavits to this effect.

salimshah

People generally never pay much attention to the air flow but it is a serious design concern. A whole lot of the air is recirculated, but fresh air is always sucked in and stale air is vented out.

The outlets in almost all the vehicles [other than trucks] I have seen are tucked in the rear bumper as they fold around the rear ... spot behind the rear wheels. There is always a rubber flap which prevent anything from entering from outside ... rodents/critters/bugs.

One more thing, these exit spots play a very important role is when you close the last open door.

Salim

pauljcl

+1, except that air is brought in from the outside unless the recirc. button is lit.

HtownBlue

I just cannot believe that we are discussing whether or not a vehicle is "air tight". Of course there are vents, but air can leak out or seep out from all over the vehicle.

The recirculate button or option simply draws are from near the glove box / dash area and blows it through coil and a/c/heater system, or draw air from near the washer blades from exterior.

Where the air vents from does not effect the temp in the car as much as how effective the recirculate and blower fan motor work together to gather said air in the first place.

tfischer

Believe it, Mr. Blue. This is far from the dumbest discussion taking place on this board.

salimshah

FWIW:

Vehicles are very much air tight. The seals are now double or triple. some is done for noise [they go together]. In recirc mode, you still get some fresh air [proportionately much less].

Good amount of money is spent in research and development. Some engineers have this as their career.

Salim

DixieLex

Minutia, does it really matter in the long run. Do these same ppl ask similar questions about the air in their homes.

pauljcl

Thank you for that comment. I thought that recirc. cut out all the outside air (which is why some cars have a limited time during which it will stay in 'recirc' mode). But I guess that only a little outside air would nonetheless require limited use.

biff44

I find it an interesting discussion!

A car has to be designed to keep carbon monoxide out of the cabin. Often there is a negative air pressure in the cabin, so the rear part has to be sealed well to keep CO out. If you take apart rear doors/hatches, you will often see plastic sheeting glued in there to help this.

A car also has to be moisture tight to keep splash water from getting into the cabin.

But, as stated, if there were a fully sealed cabin, your ears would pop every time you slammed a door shut. Also, little air would blow out of your fan when you did not have the AC in recirculation mode!

So, the engineering of controlled air leakage in the cabin is more complicated than it looks.

satz

Surprised by the animosity on here towards the OP who was asking a reasonable question. The car doesn't 'leak', but actually has vents designed to exhaust the interior air.

filmteknik

My first car was a hand-me-down Pontiac Catalina 2-door. The air flow on that was under the rear fixed bench seat (there was a raised lip to keep things from rolling under it but it air was free to go over it.). From there it went into the trunk and then forward in the gap between the inner and outer sidewalls of the car. When you opened the doors you could see small black plastic grills near the lock thing. If you looked closely through the grill, behind it was another level with small rubber vanes that would be closed normally but blow open when there was air flow. The air then left the vehicle via the small gap between the door and the fixed part of the body. No doubt that the car moving along would create a suction which helped things along.

One anecdote only slightly related. On that car one day the HVAC fan motor failed. So for a few days what I did was lower each window about half an inch. At any speed above very slow, there was enough suction created to pull air through the system so I still had working A/C. So, yeah, how air leaves a vehicle is just as important as how it enters.