When you shut off your car, do your air vents intakes close?
Discussion
I mean the vents that intake fresh air from outside to feed to the cabin. A couple in New Zealand claim they got locked inside their brand new Mazda which was parked in a garage, with the engine off, and the windows rolled up. They were in the car from seven pm at night to seven pm in the morning.
https://www.carscoops.com/2014/12/couple-trapped-i...
They tried to break the window but couldn't, and they couldn't turn on the engine to open up the vent because they didn't have the key fob. When they got inside the car, it automatically locked, then they remembered they didn't bring the key fob inside with them.
By the time they were found they were almost dead from oxygen deprivation.
There's limited studies on ventilation in stationary cars that have the vents open but the one I found said the air exchange rate is about 10-20~ times per hour if the vents are open, obviously faster if the fan is running, but as low as 0.01~ air changes per hour if the vents are closed. So with new cars at least, when the vents are closed, too little air comes inside.
The studies showed an air exchange rate of ~10 times per hour was more than enough to sustain four people and carbon dioxide levels didn't rise at all. But when the vents were shut, carbon dioxide rose to unhealthy levels (over 10,000 ppm!) very quickly. In these tests the cars were stationary and the windows were up. Since their car was off I'm wondering if the vents were automatically closed, and if this is just a one off thing or if it's normal for most new cars to do this. Also if this is the case, why automatically shut the vent when the car is off? Shouldn't it be considered a hazard in case people accidentally end up locked in the car and can't escape? Is this a design flaw?
https://www.carscoops.com/2014/12/couple-trapped-i...
They tried to break the window but couldn't, and they couldn't turn on the engine to open up the vent because they didn't have the key fob. When they got inside the car, it automatically locked, then they remembered they didn't bring the key fob inside with them.
By the time they were found they were almost dead from oxygen deprivation.
There's limited studies on ventilation in stationary cars that have the vents open but the one I found said the air exchange rate is about 10-20~ times per hour if the vents are open, obviously faster if the fan is running, but as low as 0.01~ air changes per hour if the vents are closed. So with new cars at least, when the vents are closed, too little air comes inside.
The studies showed an air exchange rate of ~10 times per hour was more than enough to sustain four people and carbon dioxide levels didn't rise at all. But when the vents were shut, carbon dioxide rose to unhealthy levels (over 10,000 ppm!) very quickly. In these tests the cars were stationary and the windows were up. Since their car was off I'm wondering if the vents were automatically closed, and if this is just a one off thing or if it's normal for most new cars to do this. Also if this is the case, why automatically shut the vent when the car is off? Shouldn't it be considered a hazard in case people accidentally end up locked in the car and can't escape? Is this a design flaw?
Edited by Charlesitis on Monday 14th February 07:43
Edited by Charlesitis on Monday 14th February 07:43
Is the vent intake (recirculate flap) closing on engine shutdown a normal thing? Friend has a BMW and said it happens with his, a few minutes after the engine is shut down the vent intakes close, sealing off the cabin. What is the reason for this and isn't it a safety hazard in situations such as this?
untakenname said:
The flap by the filter on Mazda's shuts to recirc mode (to keep rodents out most likely) when you power it off.
Saying that the door handles will still work the same from the drivers side so why he didn't just use it like a normal car is beyond me, should have his drivers licence taken away at the very least.
Makes sense. Is there a way to manually open the flap when the engine is off, or is it operated by the engine running? Saying that the door handles will still work the same from the drivers side so why he didn't just use it like a normal car is beyond me, should have his drivers licence taken away at the very least.
MattyD803 said:
I'm not convinced that ANY cars are completely sealed to the extent that they become 'air tight', even if they have a flap in the intake.
Bare in mind that the ventilation system (when not in recirc mode) operates on a 'supply only' basis, the air change is facilitated (or balanced) by virtue of having a series of vents (usually towards the rear of the car), which allows the 'over pressure' to be expelled to atmosphere. From my experience, these are normally integrated into the monocoque, behind bumpers or floor panels, typically allowing air to be pulled through the cabin when in motion due to the low pressure area void formed behind the car.
Then, on top of this, you obviously have various rubber seals, wiring grommets, gaskets and joints, which will allow infiltration.
A closed box, sure. It wouldn't be pleasant, but airtight enough to cause 2 people to suffocate? I don't think so.....although being trapped in such a situation in hot weather/direct sunlight would be a very different situation.
There aren't too many studies on vehicle AER (Air Exchange Rates) and a lot of them were conducted in the 1990's. The ones I could find that were recent showed some vehicles have very low Air Exchange Rates when the vent flap is set to Recirculate. There was a study where a number of cars were tested, and one I recall was the 2005 VW Golf, which had an Air Exchange Rate of ~0.1 ACH/hr when the vent flap was set to Recirculate. Bare in mind that the ventilation system (when not in recirc mode) operates on a 'supply only' basis, the air change is facilitated (or balanced) by virtue of having a series of vents (usually towards the rear of the car), which allows the 'over pressure' to be expelled to atmosphere. From my experience, these are normally integrated into the monocoque, behind bumpers or floor panels, typically allowing air to be pulled through the cabin when in motion due to the low pressure area void formed behind the car.
Then, on top of this, you obviously have various rubber seals, wiring grommets, gaskets and joints, which will allow infiltration.
A closed box, sure. It wouldn't be pleasant, but airtight enough to cause 2 people to suffocate? I don't think so.....although being trapped in such a situation in hot weather/direct sunlight would be a very different situation.
Jader1973 said:
What a pair of f
kwits.
I think I remember reading another article, where it said they tried to use the door handle, but the car wouldn't unlock. They had to press some button first located in a place away from the door, then try the door, but it was pitch dark and they didn't know about the button. kwits.Joey Deacon said:
Plus there are vents behind the rear bumpers to let the pressure out when you shut the doors. I really struggle to believe a car would be airtight enough to kill you.
Aren't those vents one-way flaps? They open up momentarily when the door shuts or when the fan is blowing. But in the case of the New Zealand couple in my OP, the car (Mazda) they were in had a system where the vents sealed shut when the car is off. They didn't have the key fob so they couldn't turn the car on when they were locked inside.
untakenname said:
It's behind the glove box above the cabin filter so no way to remove.
I've had two Mazdas and the horn on both doesn't work unless the car is powered up so it's likely the car did have some sort of power at the time though I doubt the occupants even tried to wind down the windows considering they didn't try opening the doors and the handle on the Mazda 3 is a very simple one:
03-2012
2012-19
2020+
Couldn't you remove the cabin air filter to open the flap? I've had two Mazdas and the horn on both doesn't work unless the car is powered up so it's likely the car did have some sort of power at the time though I doubt the occupants even tried to wind down the windows considering they didn't try opening the doors and the handle on the Mazda 3 is a very simple one:
03-2012
2012-19
2020+
Snow and Rocks said:
Yep as others have said - nonsense.
I've spent many nights sleeping in a Land Cruiser with my gf and a dog with no issues whatsoever. On one occasion after far too much to drink, four of us slept in there and even that was fine besides the lack of space. Cars are full of holes.
Wouldn't you use up less oxygen sleeping as opposed to being locked in the car and panicking? I've spent many nights sleeping in a Land Cruiser with my gf and a dog with no issues whatsoever. On one occasion after far too much to drink, four of us slept in there and even that was fine besides the lack of space. Cars are full of holes.
In India a couple of years, there was a case of a Toyota Innova stalling after the car ran out of diesel. Because the car ran out of fuel, it stalled and shut off. This caused the ventilation to turn off and also made the doors and windows unable to be opened. Both occupants (who were around 30 years old) suffocated to death as they were trapped inside of their vehicle overnight.
This was reported by One India..
A 23 year old engineer was found dead in his car with an unconscious 17 year old girl. They both got trapped inside the car with its AC on after the vehicle ran out of petrol at around 12:30 AM. The 17 year old girl just barely made it but the 23 year old died of suffocation.
A 23 year old engineer was found dead in his car with an unconscious 17 year old girl. They both got trapped inside the car with its AC on after the vehicle ran out of petrol at around 12:30 AM. The 17 year old girl just barely made it but the 23 year old died of suffocation.
MattyD803 said:
It was not the feature of "most" older cars that I ever owned (Peugeot, Ford, Vauxhall, Rover etc).....they used a purely mechanical level/arm to move the recirculation damper across.....which would rarely get touched IME, unless you were caught behind some stinking old diesel truck up a steep incline, after which you'd forget you'd put it on recirc and the windows would steam up 
Higher end stuff might have been different....
I figured. Higher end stuff might have been different....Edited by MattyD803 on Wednesday 16th February 11:28
How is a vent intake that automatically closes when the car is off not a design flaw? Especially if there's no mechanical override?
charltjr said:
Still waiting to hear which car manuals you've read which warn you about this, you were pretty emphatic about it.
Here you go.https://storagewyh.blob.core.windows.net/manuals/X...
''When Sleeping in Your Vehicle
1. Do not sleep in a parked car with closed windows. In particular, if you stay or sleep in the car with the engine running and the air conditioner or heater turned on, you can suffocate to death''
DANGER
- If you sleep while operating the air conditioner or heater with all the windows closed, You may suffocate to death due to lack of ventilation. When you operate the air conditioner or heater, ventilate frequently.
Multiple vents are provided for distributing the air, being force-circulated by HVAC blower, throughout the passenger compartment.''
Edited by Charlesitis on Friday 18th February 16:43
'Warning
Do not sleep in a vehicle with air conditioning or heating system on. It may cause serious harm or death due to a drop in the oxygen level and/or body temperature.'
https://www.kia.com/content/dam/kwcms/kme/fi/fi/as...
Nothing to do with carbon monoxide since the Kia e Niro is electric.
Do not sleep in a vehicle with air conditioning or heating system on. It may cause serious harm or death due to a drop in the oxygen level and/or body temperature.'
https://www.kia.com/content/dam/kwcms/kme/fi/fi/as...
Nothing to do with carbon monoxide since the Kia e Niro is electric.
charltjr said:
Thank you.
We seem to have gone from don’t sleep in a turned off car because you’ll suffocate to don’t sleep in a car with the engine running to keep the AC or heater running - which is definitely a bad idea for many reasons.
Ref the Kia, that’s boilerplate text in all their handbooks.
So still no actual evidence that sleeping in a car with the engine off is dangerous.
The Kia e Niro is an electric car. Why would it make a difference if the engine is off?We seem to have gone from don’t sleep in a turned off car because you’ll suffocate to don’t sleep in a car with the engine running to keep the AC or heater running - which is definitely a bad idea for many reasons.
Ref the Kia, that’s boilerplate text in all their handbooks.
So still no actual evidence that sleeping in a car with the engine off is dangerous.
Mr Tidy said:
Maybe because the power-plant is off? Does it have an engine if it is electric?
Anyway the air vents in my E90 BMW 3 Series do close/open when I use it.
I heard the air vent intake closes to the 'recirculate' position when the engine is off. The same happens when the heater/AC is on so I think this warning would still apply when the engine is off because the fresh air intake is closed and the door seals aren't going to let in very much new air, if any.Anyway the air vents in my E90 BMW 3 Series do close/open when I use it.
Gassing Station | General Gassing | Top of Page | What's New | My Stuff