Strange odor when AC running

[sleestak]

I've had too many BMW models to list but all of them have had this strange ammonia type smell coming from the dash vents. Eventually dissipates but does anybody else have this problem? It's only with BMWs. What the hell is it and why?? AC is fully charged and doesn't have any mechanical issues.

For my 2013 X5 (now sold) BMW literally removed the entire dashboard to replace the turbos believing that's what caused it! I thought it was nonsense! Anybody else getting this strange odor?

[eatsleepboost]

Just with a/c or heat too? If it's only with a/c I would say you have an evaporator leak. If it's with heat too then I would check your cabin filters. May have mildew buildup. Could remove HVAC filters and spray professional odor neutralizers and mildew treatment then install new filters. You could also try recirc instead of vent as it's possible you are getting a smell off the engine such as hot burning oil/coolant.

On the flip side, this is my first BMW and I do notice a smell anytime I turn on the HVAC blower but it's not offensive. More like plastic smell.

[Theodore]

Check out this member's post for the likely reason this happens:

Mvy

And this member's post for a possible workaround, however inconvenient:

JonM

And here is a video of the service suggested to clean up the system:

[Mvy]

Thanks for quoting my previous post Theodore.

I used this from Amazon to fix smells. It works really well and lasts a while:
nextzett 96110515 Klima-Cleaner Air Conditioner Cleaner - 10 fl oz $18

I have a 10 year old evaporator and my AC is still blowing nice and chilly. When it starts to blow warm and not hold a Freon charge, thats when I start to suspect an evap leak is likely. If its just an odor, its typically the buildup of bacteria on the evap that gets to smelling bad especially in the warmth of summer.

You open the hood, remove the cabin air filter cover and turn the ac on, then spray this into the flap that opens on the left side. It lasts for a year and a half or two then you have to do it again. Easy DIY and works like a charm.

[tooloud10]

Does it smell like band-aids? If so, it is the A/C evaporator problem, and replacing it involves removing the dash again. Just one of the reasons I dumped my E70 X5. A/C was incredibly weak in mine until this was diagnosed.

I'll never understand how they can't get this stuff right. You can buy a basic domestic SUV and never run into this problem, but it seems very common on BMWs.

[dgoldenz]

Originally Posted by tooloud10

Does it smell like band-aids? If so, it is the A/C evaporator problem, and replacing it involves removing the dash again. Just one of the reasons I dumped my E70 X5. A/C was incredibly weak in mine until this was diagnosed.

I'll never understand how they can't get this stuff right. You can buy a basic domestic SUV and never run into this problem, but it seems very common on BMWs.

My evaporator went at 35k miles on my first e92. Fortunately covered under an extended warranty. USAA paid them $3400 for the job. I agree it’s pretty ridiculous how unreliable some of these parts are. Still worth it...

[Mvy]

Originally Posted by tooloud10

Does it smell like band-aids? If so, it is the A/C evaporator problem, and replacing it involves removing the dash again. Just one of the reasons I dumped my E70 X5. A/C was incredibly weak in mine until this was diagnosed.

I'll never understand how they can't get this stuff right. You can buy a basic domestic SUV and never run into this problem, but it seems very common on BMWs.

The smell is unrelated to the failure of the evap. You had an evap falilure and bacteria build up. I must be one of the lucky ones on my original evap.

[tooloud10]

Originally Posted by Mvy

The smell is unrelated to the failure of the evap. You had an evap falilure and bacteria build up. I must be one of the lucky ones on my original evap.

Not sure what you mean--in a huge number of BMWs (and in mine), a band-aid smell is definitely related to the failure of the evaporator. The OP hasn't really clarified the smell beyond 'ammonia'.

[dparm]

Originally Posted by Mvy

nextzett 96110515 Klima-Cleaner Air Conditioner Cleaner - 10 fl oz $18

I have always used this twice a year on all my cars (and even my parents'). I typically do it at the same time I change the wiper blades, which is the spring and the fall.

Give this a shot, OP, and see if it fixes things.

[Mvy]

Originally Posted by tooloud10

Not sure what you mean--in a huge number of BMWs (and in mine), a band-aid smell is definitely related to the failure of the evaporator. The OP hasn't really clarified the smell beyond 'ammonia'.

Its a common misconception that the smell is indicative of evap failure. I'm arguing that its two separate things because many cars in warmer climates starts to develop funky AC smells, but have a good working AC that blows cold air year after year. Read this from the BMW service manual. It clearly states replacing the evap wont solve the moldy smell because its not a problem with the evap itself. Smell is highly subjective so ammonia, moldy, band aid as a description is probably the same underlying issue of microbe growth creating odors. I just assume we all smell it differently based on what kind of baddies are growing in there. I dont think freon has a smell, so if you were smelling the refrigerant leak as an indication of a crack in the evap, that would be something I had not heard before.

https://www.m3post.com/forums/showpo...4&postcount=18

I stand by what I said as I believe its two separate issues that you can have at the same time. The OP indicated his AC works fine (fully charged) other than the smell. So a cheap $18 solution is the best bet. If it was a failed evap, the ac wont cool because it has a leak in it. The crack/hole symptoms are the system wont hold freon or blow cold air. To fix a failed evap you have to pull the dash for $$ big bank. If its just a smell, and the AC still pushs cold air, its likely related to the environmental conditions the evap creates (namely moisture, warmth and darkness ideal for bacteria growth) especially during the summer months. You can fix the smell for $18 without an evap replacement because its just crap attached to the outside of the evap you can attack with a sanitizer/anti microbial agent through the hood without having to remove anything more than the in cabin air filter.

I have heard of BMW talking people into evap replacements for smells. I just hope to prevent such nonsense with the above information. If she blows cold, the dash removal can hold ;-)

[samsh12345]

Originally Posted by sleestak

I've had too many BMW models to list but all of them have had this strange ammonia type smell coming from the dash vents. Eventually dissipates but does anybody else have this problem? It's only with BMWs. What the hell is it and why?? AC is fully charged and doesn't have any mechanical issues.

For my 2013 X5 (now sold) BMW literally removed the entire dashboard to replace the turbos believing that's what caused it! I thought it was nonsense! Anybody else getting this strange odor?

hi, a newbie from Torronto
man, i had the same problem. I understand, that's really annoying,
vents in my BMW M5 gave off the smell of mold, so that was unbearable to travel far and to stay in the car for a long time

[nrubenstein]

If the AC works, it's almost certainly mold / mildew on the evaporator. If there's a smell related to a leak, the system won't hold a charge for long.