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-   -   Traffic smell entering Cabin through the Boot (https://www.team-bhp.com/forum/technical-stuff/153210-traffic-smell-entering-cabin-through-boot.html)

I have observed this issue in my 2012 Verna.

After driving in traffic with all the windows closed and A/C in recirculation mode for sometime, I would start smelling the road-traffic smell inside the passenger cabin. Initially, I thought the smell is seeping through some gap in the area where the A/C sucks outside air. But I ruled this out after passing through multiple areas covered in smoke and I did not get the smell inside the car.

I also observed that this smell is very close to how the boot smells (the smell of the boot fabric mixed with the smell of traffic smoke).

Then I recently bought a car freshener. After parking overnight, when I opened the boot the next morning, it was full of the smell of the freshener. This is when I confirmed that there is some kind of an air flow between the cabin and the boot.

Since the boot is not air tight, it can easily get filled with the traffic smell and it seeps into the passenger cabin slowly.

I see this as a health hazard and I would like to make the passenger cabin and/or the boot air tight. Have any of you observed this? Is it possible to fix a rubber lining to the boot to make it air tight?

I hope this is intentional design and not a flaw.
We do have air drafts that allow air to pass through / pass out when we close the doors / boot. The same avoids vacuum build when we open the doors

I may be wrong, please correct me if so.

Check whether the flap that closes the outside air vent when you switch to recirculation mode, is actually working or not. An AC mechanic will do it for you easily.

Also check the door seal rubbers for cuts or whether displaced.

Highly unlikely that traffic smell seeping into the boot (in the rare instance that it does seep in) will come forward to the driver seat.

The most common point of ingress of traffic smell is from the recirculation / fresh air flap. Many years ago, I had the same experience in my Lancer. It was solved by attending to the flap, the sealing strips had worn.

Do you have split rear seat backs in this car? Maybe that might be an area where air is leaking. Some stench travel faster and hence you feel it. I commute in traffic without any smoke or such smells, but the moment i pass by a drain which is known for its stench, somehow the smell seeps in. Happens in multiple vehicles.

This was my first doubt too, but I ruled this out when I drove through smoky/smelly areas and the smell did not come in through the recirculation flap. I verified this multiple times.

No, the 2012 Verna doesn't have split or even folding seats.

I verified the door seal rubbers in the boot and they are fine. However, this is one area where I suspect the smoke could pass through because, the boot door may not shut as tightly as the front/rear doors.

I will continue to investigate the cause of this issue.

As SS-Traveller has rightly said, even if the boot is allowing air in, it's not possible to detect it from the drivers seat. Outside smells entering the cabin is caused 99.9% by the fresh air vent malfunctioning.

I suspect three likely causes:
One, the motor controlling the fresh air door is either malfunctioning and as a result has left it in fresh air mode which you would not be able to see, of course.
Two, if you use your ac in auto mode, in this situation the car decides when to have fresh air and when to recirculate on its own after sensing various outside parameters like ambient air temp. for example. This process continues automatically in a cyclic manner and you might sense the odours when the system opens fresh air mode and it may have gone back to recirculating by the time you reached your favourite smelly spots along the road ;) so you would'nt know.
Three, in rare cases, the system itself leaves the fresh air mode on by some software error or error in ecm codes etc.

Anyways you would need to show an ac specialist the car to go throught all the check points. By the way, fresh air entering with ac on drastically reduces ac effectiveness too in our Indian environment. Do the needfull. All the best.

I am very sure that the smell is not coming through the A/C air vents as I had tested it multiple times. Also, in the Verna, the Auto A/C does not switch to fresh air mode on its own. I always keep it in recirculation mode (except for few minutes in the morning to fill the vents with fresh air).

As I had stated earlier, the smell is very similar to how the boot smells and the smell seeps in only after driving in the traffic for some time. And, on some days, I keep the boot open for some time to fill it with fresh air and this issue comes very late.

Since any fabric has a tendency to absorb the smell they are exposed to, I strongly suspect that the boot fabric also plays a role in retaining the traffic smell. I will give it a foam treatment and see if the issue persists.

Could you explain / elaborate on the testing procedure(s) used?

All these observations are made with A/C running in recirculation mode and windows closed.

1. The smell comes inside the cabin only after driving in traffic for sometime (more than 30 minutes). If there was any leakage in the A/C flaps, the smell would come in soon after I drive in traffic, which is not the case.
2. I have driven the car through smoky and stinking areas and I observed very keenly (smelled the air directly from the A/C vents), the outside smell did not come in the A/C vents.
3. Even the smell of rain would not seep inside the cabin through the A/C vents.
4. I have observed that, once the smell starts entering the cabin, it increases right after I brake in traffic, leading me to believe that the air from the boot is pushed inside the cabin because of the braking.

I'd suggest once again that you take the car to an AC mechanic, or get a Hyundai ASC's AC technician (not the service advisor) to take a thorough look at the fresh air flap under the dash. No point in drawing your own conclusions from your own observatons.

The boot will not allow percolation of traffic / road smell to the driver seat in a sedan, so stop speculating/theorizing on that.

I beg to differ on this point. The boot very much gets the smell of the car freshener I started using recently, so there is a definite passage of air between the boot and the cabin. So the reverse (boot to cabin) is also possible.

From the time I started using the car freshener (last 10 days), I could not smell any traffic, because now the boot is also having the smell of the car freshener and the car freshener is obviously stronger than the traffic smell.

I now need to check if the boot rubber seals are really air tight. I will also get my A/C flaps checked.

Like most others, I would say that 99% chance that the problem is from the ventilation control flaps. However, I will not say it is impossible coming from the boot. (This is separate from traffic smells.)

When the smell is strongest, are you carrying passengers on the rear seat?

I would suggest an experiment: Spray some distinctive and strong deodorant in the boot. (Close the boot lid gently.) See if you get the smell in the cabin later on.

Regards
Sutripta