Outside smoke smell entering Innova's cabin through back aircon

[oj88]

the noxious fumes that the engine generates, do not need the aircon and vents to enter the passenger compartment.
they enter thru the imperfect seals of the firewall, between the engine and the passengers.
if the passenger compartment has no venue to vent these fumes out, the build-up becomes potentially fatal.

Unless you have your tail pipe in the engine bay or if there are oil or fuel leaks, there should be zero noxious fumes coming from your own engine that is not being spewed out as exhaust gas. I did mention that there's only trace amounts of outside air coming in. Why? Because there's not much airflow to and from the cabin. The only two ways for airflow to happen is a) Force it or b) Pressure imbalance.

By forcing, you need to have a fan or blower doing the job. By pressure imbalance, if the pressure inside the cabin is high, air flows out until balance is achieved, and vice versa.

If your recirculation flap isn't closed, the A/C would pull in outside air making the cabin slightly pressurized, which then causes cabin air to go out of the rear vents. The firewall is not airtight and it doesn't have to be. If the inside and outside pressure is the same, there will be no airflow.

The joke is, only NASA would develop an airtight cabin.

[oj88]

I'm very glad to report that the changes I made >here< and >here< made a HUGE difference. I can no longer detect outside air coming in from the rear A/C.

Blocking those holes seemed to have done the job so well that even if I have the rear A/C blower at maximum, I can smell nothing... exhaust gases, garbage fumes... nothing. This mod will also prolong the cleaning interval for the rear evaporator. Since it doesn't have a filter, outside air coming in, if not corrected, will make it more likely to clog up with muck sooner than later.

I'm still thinking of going one step further and that is to open up the side panel where the rear A/C blower is and try to actually divert the blower intake to only recirculate air from the cabin. Maybe even figure out if I can fit an air filter somehow.

[oj88]

Duplicate......

[jick.cejoco]

Not advisable to make the car cabin air tight. If the car sits out in the sun on a hot soak, there is a risk of the cabin pressure pushing the windshield out or other glass to relieve pressure

[first_light]

May nag post na before dito ng mga pics on how to clean the rear ac compartment.
I've done it before, too (cleaned the rear ac blower with brush).

Sealing the vent in the vehicle will minimize the quantity of O2 coming in as it increases the CO2 level inside the cabin.
If a bad smell is coming in, what I do is I switched off the rear AC and increases the speed of the blower of the front AC for sometime to pressurize the cabin until mawala yung bad smell.

[first_light]

Btw, to avoid double-post, after you typed your message, just click "Go Advance", then "Submit Reply".

[oj88]

Not advisable to make the car cabin air tight. If the car sits out in the sun on a hot soak, there is a risk of the cabin pressure pushing the windshield out or other glass to relieve pressure

May nag post na before dito ng mga pics on how to clean the rear ac compartment.
I've done it before, too (cleaned the rear ac blower with brush).

Sealing the vent in the vehicle will minimize the quantity of O2 coming in as it increases the CO2 level inside the cabin.
If a bad smell is coming in, what I do is I switched off the rear AC and increases the speed of the blower of the front AC for sometime to pressurize the cabin until mawala yung bad smell.

It's hardly airtight. Particularly, the left vent is unrestricted. Only the right vent was made a little bit more restrictive to make the rear blower pull in more recirculated air than outside air.

The front A/C is also pulling in a bit of outside air than I'm comfortable with, even in recirculate mode. I'm also thinking of reducing this as well.

I drove a Civic which never had this problem. After driving it for almost 8 years, not one of us felt sick. The interior smells clean. Compared it to the Innova, the latter, I occasionally do actually smell exhaust gases coming in through the A/C, front and rear. The rear was a lot worse.

[oj88]

I have made further modifications to the AHU in my Innova to significantly reduce outside air from entering the cabin. I have successfully fixed the rear A/C several months earlier (see previous posts) and this time, I focused on the front A/C.

The problem is, even with the Recirculation mode turned ON, there's still significant amount of outside air going in.

Encircled here is the ducting that brings in outside air into the cabin. (Not my picture).


This is what it looks like when looking inside from the cabin air filter hole (behind the glove box)...

Recirculation ON:


Recirculation OFF:


Even with the Recirculation mode turned ON, the recirculation flap does not provide enough snugness to close the outside air duct. Because of that, significant amount of outside air and dirt seeps through the gaps and onto the cabin air filter. When I checked my cabin filter a few days ago, it was almost black with soot. Considering that my Innova is just 10 months old and I always have the Recirculation mode turned ON.

The picture below shows just how much dirt gets through from the outside. This is also the reason I smell exhaust gases from the outside and why there's fine dust and soot everywhere inside the cabin.


So what I did was, I stuffed the intake duct with aircon filter refill material, similar to the picture below.


Doing this has helped significantly cut down the flow of outside air going in. The filter just restricts air coming in so there's no danger of suffocating. When air does enter, it will have to go through thick/folded layers of this filter. By the time it reaches the actual cabin filter, it's pretty much already clean.