[yousefnjr]

I’m a serial AC-recirc dumdum and now I’m paying the price with a little bit of funk coming through the vents when I first start the car. Anybody else going through the same and have luck getting rid of the smell? On my old i3 I sprayed a shitload of Lysol through the windshield cowl and that seemed to work ok, but I see there’s also some foams available that can be applied through the AC drain under the car. Supposedly they’ll make their way to the evap and then drain back down. Other folks (e9x) say they remove the blower motor from the cabin and spray onto the evap directly.

Any thoughts? Leaning towards the foam, need to get under the car and see if I can find the drain though

[kjx]

Originally Posted by yousefnjr

I’m a serial AC-recirc dumdum and now I’m paying the price with a little bit of funk coming through the vents when I first start the car. Anybody else going through the same and have luck getting rid of the smell? On my old i3 I sprayed a shitload of Lysol through the windshield cowl and that seemed to work ok, but I see there’s also some foams available that can be applied through the AC drain under the car. Supposedly they’ll make their way to the evap and then drain back down. Other folks (e9x) say they remove the blower motor from the cabin and spray onto the evap directly.

Any thoughts? Leaning towards the foam, need to get under the car and see if I can find the drain though

Huge coincidence that you posted this today.

My M4 does not have this problem.

But my X5 does (2021, 2 years old exactly). It just had its cabin air filter replaced but with little effect on the AC smell. They are looking at it today. Some guy has filed a class action against BMW NA saying their ACs are defective and hold condensation resulting in mold/mildew and that yucky rental car smell from the AC.

My cars are maintained pristine clean and otherwise smell great (even the carpets) so I know this is purely within the AC system. I’m guessing mildew on evaporator but let’s see.

My SA said they will look into it but if it is “environmental” the cost is on me. I’ll pay if needed as I can’t have high-end cars smell like this. If I have to pay, I’ll be closely watching what happens with the lawsuit to recover my costs as I do think there is something defective with the system given my efforts at cleanliness.

[kjx]

Oh and I tried Lysol and letting the X5 run with heat on high for half an hour (easier to do in the 45e as it can run the HVAC on full electric). Did very little except overpower my nose with the smell of Lysol.

I’d suggest taking it to the dealer unless you’re a good DIY kind of guy.

[Nate.G82]

Forgive my ignorance as I didn't know this was an issue. But having the AC recirculation on all the time leads to a mildewy kind of smell in the car?

Edit: Read into it a bit and I guess it does if the moisture gets trapped. Hopefully that foam works out for you OP. Otherwise, I'd get it checked out at the dealer.

[DO444]

Originally Posted by kjx

Huge coincidence that you posted this today.

My M4 does not have this problem.

But my X5 does (2021, 2 years old exactly). It just had its cabin air filter replaced but with little effect on the AC smell. They are looking at it today. Some guy has filed a class action against BMW NA saying their ACs are defective and hold condensation resulting in mold/mildew and that yucky rental car smell from the AC.

My cars are maintained pristine clean and otherwise smell great (even the carpets) so I know this is purely within the AC system. I’m guessing mildew on evaporator but let’s see.

My SA said they will look into it but if it is “environmental” the cost is on me. I’ll pay if needed as I can’t have high-end cars smell like this. If I have to pay, I’ll be closely watching what happens with the lawsuit to recover my costs as I do think there is something defective with the system given my efforts at cleanliness.

Had this issue with an older bmw.
It started having a very sweet smell through the AC, didn’t know if it was due to the guys spilling something while working on it but it then got a bit musty.

BMW said it was due to the ac running hard in the summer and then stopping right away once I got home, something about water condensation. They told me, and this is not ideal, but they told me not to run the ac for five minutes before I get home lol… so the system has time to warm up and dry out before I park. Never heard of that before in any other car and it’s never happened in any other car.

AC will naturally accumulate “some” smell over time (years), but this was like vinegar. It was pretty bad. Eventually they did reduce the problem greatly by bombing the system with something that smelled like mint. It did work to greatly reduce the vinegar odor and it never came back as strongly, was almost imperceptible.

But, it was an unpleasant month or so while I had to deal with that smell and then the smell of mint on top of it. I was kinda surprised that their solution did work though.

If they offer to replace your filters and bomb the system I’d say go for it.

[BzsBimmer]

There’s a process that has been used countless times on my prior BMW’s and Merc’s. Removing the cabin filter and squirting Nextzett Klima Cleaner while the fan is spinning. The condenser drain will purge it all out assuming it’s not blocked.

You may need to remove glove box etc to get to it. I don’t have my G8X to tear apart.

[yousefnjr]

Originally Posted by Nate.G82

Forgive my ignorance as I didn't know this was an issue. But having the AC recirculation on all the time leads to a mildewy kind of smell in the car?

Edit: Read into it a bit and I guess it does if the moisture gets trapped. Hopefully that foam works out for you OP. Otherwise, I'd get it checked out at the dealer.

Yep, as another poster mentioned you’re supposed to run fresh air or no AC for a few minutes to help dry it out, but I don’t have that kind of discipline lol. Kind of a farmy area around me, so it’s either recirc and a little foot smell or fresh cow shit air

Originally Posted by BzsBimmer

There’s a process that has been used countless times on my prior BMW’s and Merc’s. Removing the cabin filter and squirting Nextzett Klima Cleaner while the fan is spinning. The condenser drain will purge it all out assuming it’s not blocked.

You may need to remove glove box etc to get to it. I don’t have my G8X to tear apart.

I’ll take a look a little later, maybe that’s easier to get to than under the car. I did buy that same cleaner. Should be here in a couple days. I’ll update the thread with how this turns out.

[kjx]

The smell's gone. They performed "HVAC System Check and Vent De-odorization". No charge. Note: "Constant AC operation is required to dehumidify system and remove odor".

[jmg]

Originally Posted by yousefnjr

Yep, as another poster mentioned you’re supposed to run fresh air or no AC for a few minutes to help dry it out, but I don’t have that kind of discipline lol. Kind of a farmy area around me, so it’s either recirc and a little foot smell or fresh cow shit air




I’ll take a look a little later, maybe that’s easier to get to than under the car. I did buy that same cleaner. Should be here in a couple days. I’ll update the thread with how this turns out.

Copy pasting a reply I made years ago:

Originally Posted by jmg

This can actually promote mold and mildew growth which increases the chances of bad smelly AC if you do it too soon before you turn off your car. When you blow non-conditioned air through the vents, you are introducing relatively humid air to the interior of the air ducts. The ducts are still relatively cold from the previous use of air conditioning. As the ducts warm, they collect moisture from the warmer, humid air on the inside and condensation forms on the interior. If you leave the air on long enough, it might cause the condensation to evaporate, but if you turn the car off, the condensation remains, and you can introduce mold and mildew. Note that it takes MUCH MUCH longer for the condensation to evaporate than it did to form. You would have to turn your AC off a very long time for you to ensure that it all evaporates.

Alternatively, if you leave the AC on before you turn off the car, the air in the ducts are relatively low humidity. That means when the ducts start to get warmer, there is significantly less condensation on the inside of the ducts because the air is conditioned aka dry. Note that the condensation on the exterior of the ducts is less of a problem because even if mold and mildew grow on the exterior of the duct, our HVAC air runs through the interior, thus no smell.

So, if you had to chose between turning your AC off or leaving it on... it's almost always better to just leave it on and leave it on always. Remember, moisture is bad, and AC is basically a dehumidifier.

In short: there is very little moisture in your AC ducts since AC is a dehumidifier.

[yousefnjr]

Originally Posted by jmg

Copy pasting a reply I made years ago:




In short: there is very little moisture in your AC ducts since AC is a dehumidifier.

maybe so but I’ve never turned off the AC in the car in the year I’ve had it, and here we are unfortunately. I have to imagine that there’s a decent amount of water in there otherwise they wouldn’t have drains, no? Haven’t looked at the M4 specifically but I remember my i3 used to piss water during the summer

[jmg]

Originally Posted by yousefnjr

maybe so but I’ve never turned off the AC in the car in the year I’ve had it, and here we are unfortunately. I have to imagine that there’s a decent amount of water in there otherwise they wouldn’t have drains, no? Haven’t looked at the M4 specifically but I remember my i3 used to piss water during the summer

Moisture will form on your evaporator coils regardless if you turn your AC off before you stop the car or not. This is how it dehumidifies the air as it passes through the cooled coils and enters your HVAC vents. If you leave the AC on until the car is shut off, the water drains out. However, if you turn the AC off before you stop the car, the fan is still blowing, and the incoming air is going to have ambient moisture in addition to whatever moisture it picks up from the coils.

While the evaporator can efficiently drain fluid, the vents cannot, so you would rather the coil retain the moisture instead of distributing it to the vents.

If you still experience a stinky HVAC, it’easier to clean the evaporator and make sure the drainage is clear than to try and clean the vents with air.

[Ximian]

Sometimes the filters get "clogged" up with funk and replacing them is all you need to do. I made the mistake of putting a couple of bags of compost in the passenger footwell for the short drive to the drop off location. This was in a different car and the intake for air recirculation is in the footwell. The next day, horrible smell when running the air that goes away after a couple of minutes.

I didn't suspect the filter because it was changed weeks prior. I cleaned the vents, made sure the drains were clean, all with no benefit. I finally got the air filter out to get a better view of the system and the smell hit me. Replacing the filter fixed it and we keep the air recirculate on all the time in the summer.

[yousefnjr]

Originally Posted by Ximian

Sometimes the filters get "clogged" up with funk and replacing them is all you need to do. I made the mistake of putting a couple of bags of compost in the passenger footwell for the short drive to the drop off location. This was in a different car and the intake for air recirculation is in the footwell. The next day, horrible smell when running the air that goes away after a couple of minutes.

I didn't suspect the filter because it was changed weeks prior. I cleaned the vents, made sure the drains were clean, all with no benefit. I finally got the air filter out to get a better view of the system and the smell hit me. Replacing the filter fixed it and we keep the air recirculate on all the time in the summer.

Good idea. Don’t think I’ve had anything smelly in the car other than my kids, but I’ll give this a try anyway. Just ordered cabin air filter PN 64119382886

[yousefnjr]

Update — I ended up removing the cabin air filter, and spraying a can full of the ‘Nextzett Klima Cleaner’ up the hose for the drain that connects to the cabin air filter cover. I tried to see if I could reach the evap directly, but couldn’t seem to find a way to get there. Popped in a new cabin air filter and buttoned it back up. Turned the car on and ran the AC for a while. It’s been 2-3 weeks and the smell hasn’t returned at all, not even a tiny bit. Thanks all for the tips.

Cabin air filter removal —
https://g80.bimmerpost.com/forums/at...5&d=1648490579

[jmg]

Originally Posted by DO444

BMW said it was due to the ac running hard in the summer and then stopping right away once I got home, something about water condensation. They told me, and this is not ideal, but they told me not to run the ac for five minutes before I get home lol… so the system has time to warm up and dry out before I park.

I never do this and none of my cars smell. This is a old wives tale, and turning the AC off could potentially make things worse.

First of all, the evaporator coil does not need to be dry. Mold and bacteria don't just grow out of nothing, spores need to be introduced. An effective cabin air filter prevents these spores from ever reaching the evaporator coil and the drain allows the moisture to escape.

Additionally, turning the AC off before you park actually increases the chance of mold and bacteria growth. When you turn the AC off while the fan is blowing, it quickly introduces humid air into the vent inner ducting. This dramatic increase in humidity and temperature causes condensation on the cool inner ducting walls. If you don't run the air long enough to dry out the system, then you risk potential growth of mold and bacteria on the residual condensate.

In comparison, if you simply let the AC run, humidity rises gradually when the car is turned off, which doesn't allow for condensation on the inner vent to form in the first place.

So really, by switching the AC off, you're creating a problem you didn't have to solve in the first place.



The final source of mold and bacteria growth is the cabin. Again, mold and bacteria don't just grow out of nothing, spores need to be introduced to a growth conducive environment. Air is filtered coming into the cabin, but air is not filtered from the cabin into the vents and inner ducts. So, if you turn the AC off before you park, and don't let it dry completely, then the potential for spores to grow on that condensate increases.

Instead, let the AC run so condensate doesn't form in the first place and the spores have nothing or significantly less to grow on.

You can further reduce the risk by keeping the cabin clean. No food or trash from food should ever be left in a parked vehicle.


tl;dr - they don't know what they are talking about. Keep the AC running, check your cabin air filter, evap drain, and keep your cabin clean.

[Needsdecaf]

Change your filter. Use this, spray it in the air intake. Make sure you don’t use recirc too much.

https://www.bgprod.com/catalog/clima...g-frigi-fresh/

[jmg]

Originally Posted by Needsdecaf

Change your filter. Use this, spray it in the air intake. Make sure you don’t use recirc too much.

https://www.bgprod.com/catalog/clima...g-frigi-fresh/

Forgot to mention this. Recirculated air is still passed through the filter before it passes the evaporator coil, so using recirculation is generally fine unless the cabin is especially dirty and the cabin air filter is dirty.

A dirty filter will push more of the particulate that have gathered on the surface through to the system, so recirculate could make a bad situation worse if the filter is old and there is already material building up on the evaporator coil.

So if someone is already experiencing AC stink, definitely don't use recirculation.

[DO444]

Originally Posted by jmg

I never do this and none of my cars smell. This is a old wives tale, and turning the AC off could potentially make things worse.

First of all, the evaporator coil does not need to be dry. Mold and bacteria don't just grow out of nothing, spores need to be introduced. An effective cabin air filter prevents these spores from ever reaching the evaporator coil and the drain allows the moisture to escape.

Additionally, turning the AC off before you park actually increases the chance of mold and bacteria growth. When you turn the AC off while the fan is blowing, it quickly introduces humid air into the vent inner ducting. This dramatic increase in humidity and temperature causes condensation on the cool inner ducting walls. If you don't run the air long enough to dry out the system, then you risk potential growth of mold and bacteria on the residual condensate.

In comparison, if you simply let the AC run, humidity rises gradually when the car is turned off, which doesn't allow for condensation on the inner vent to form in the first place.

So really, by switching the AC off, you're creating a problem you didn't have to solve in the first place.



The final source of mold and bacteria growth is the cabin. Again, mold and bacteria don't just grow out of nothing, spores need to be introduced to a growth conducive environment. Air is filtered coming into the cabin, but air is not filtered from the cabin into the vents and inner ducts. So, if you turn the AC off before you park, and don't let it dry completely, then the potential for spores to grow on that [...]

Yea, the smell happened right after they performed an oil change. It had a vinegar smell, immediately after getting the car back.

I no longer have the car anymore however.

[BzsBimmer]

Originally Posted by DO444

Yea, the smell happened right after they performed an oil change. It had a vinegar smell, immediately after getting the car back.

I no longer have the car anymore however.

It was someone’s dirty feet 🤣

[DO444]

Originally Posted by BzsBimmer

It was someone’s dirty feet 🤣

Lol, Yea.
Could have been anything really.

Maybe the tech was sweaty or they decided to take the air filter and dip it in a jar of pickles.

Who knows.
I’m used to the car smelling a bit from spilling oil, on occasion that’s happened, but vinegar was a new one.

It eventually went away, after they bombed the ac and replaced filters.

Now, whenever everything is not exactly as it was when I take the car back, I won’t even drive off the lot. It’ll go right back to them and I won’t take it until it is right.

Of the greatest benefits of having multiple vehicles tbh.

In most dealerships, you get absolutely nothing for being nice anymore.