Practical advise for managing AC stink

Practical advise for managing AC stink

This is an advisory post, if you don't like it, do not take it :)

The info I share is based on MY understanding of the 3, and forum engagement. I've had my 3 since January 2018, and now have 42K miles, so I have a fair bit of experience with the car. I am NOT anyone with automotive or refrigeration background. I am definitely not a Tesla devotee/fanboi/investor, nor am I someone who wishes ill upon Tesla - I think of myself as a Tesla customer first, and a definite admirer of most things Tesla.
So, if you're looking for expert advice, seek elsewhere. This post is for simple folks who just want this stink gone.

What I experienced:
I experienced the vinegar smell/stink very early in my car ownership, then it just went away. There was a definite flurry of complaints from early owners, talk of a fix, and then the smell just went away for me.
The smell is back after approximately 15 months and it’s strong now.
Between the two occurrences, I have noticed changed HVAC behavior.

My advice-

If you have strong stink:
I advise you to clean the AC system. Because, If the stink is strong there is no quick fix that any software can help you with. Let your nose decide if it requires cleaning.
There are excellent accounts on how to do it by @frank99, and @pmagid. I’ll provide the link below. Their method basically asks you to spray a cleaning agent into the innards of the AC system - this is normal AC cleaning stuff nothing fancy, or hazardous.
Inspect the filters, most likely they should be fine because these are newish cars. If they’re OK dry them out in the sun. That should kill most of whatever might be growing there. If you’re like me, you may want to spray some household disinfectant on it and then dry them in the sun. Since I pulled them out anyway, I vacuumed and ‘refreshed’ them, because - why not?

If you have a weakish odor:
This is probably a situation where you can avoid cleaning the system by drying it out. No big science here, just dry the system out and make sure the conditions for stinky stuff is eliminated. You can do this by running the fan a little while to dry the system out, I do this at the end of each drive. Others are running the heater on, some others or running the AC with recirculation on - they’re all basically trying to dry the system out. The most popular advise based on forum posts is to run the fan only for a few minutes after each drive with the AC OFF - simple, effective. This should get rid of the smell a little bit without opening anything on your car

If you have no odor and would like to avoid the problem:
I advise you to do the same things as above ^^

About the software fix for this problem:
I believe the forum members and Tesla technicians who indicated that there is a software fix for this problem. Why? That’s because of the following reasons:
- Multiple owners have no reason to lie
- Multiple Service Technicians have no reason to lie
- Tesla would be embarrassed if this isn’t a software fix. Because a hardware fix would suggest a poorly engineered AC system
- Because I noticed how the stink went away after my first encounter with the stink early into my ownership. The only thing that changed in my car since then was software

Bottom line:
My advice is to manage the stink by cleaning/drying the system out, and then wait for the software update to fix it.

The link to help you cleanse the system:
Please give the credit to @Frank99 and @pmagid - Their advice caught my eye, there may be others who did just as much, thanks all.

Info from folks who went to the service center (if you care to believe service center info as relayed by owners)

steve | 29. august 2019

Many cars get A/C stink after a year or so - the usual fix is to swap (or perhaps clean) the cabin air filters. On most cars (no idea about Tesla) these filters can be bought just about anywhere and are pretty cheap - so just change them.

This is really no different than the advice to change the air filters on your home A/C system...and for the same reason. All sorts of biological stuff (dead skin cells) gets stuck in them - and when bacteria move in to chomp on it - they can make a stink. There is nothing any car manufacturer can really do about that.

Cleaning the ducts shouldn't normally be necessary - but I've heard of people who did have to do it. In one case that I heard of from a classic car forum - a mouse had somehow gotten into the ductwork and then died. Well, THAT would be impressively stinky and v.hard to eradicate. Cleaning out the ductwork would certainly be needed in those kinds of cases.

But the stink in a brand new car would be things like the chemicals left on the plastics after manufacture - and I'd certainly expect that to go away (and never come back) after a few days/weeks of driving. There isn't a whole lot anyone can do about that - so you live with it.

vmulla | 29. august 2019

There's a history to this issue on this forum. Cars as new as a few months old have reported this problem.

WRT chemical smells, When the issue was first reported many of us early owners did suspect chemical smells from manufacturing, I've alluded to that in my very first post on this matter (July 19, 2019). However, with time that theory did not hold up. This smell is from other sources.

tri_t_to | 29. august 2019

I brought my M3 to the service center to replace the filter and clean out the evaporator to remove the stink. 2 months later it's back again. I think there might be some design issue with the AC system. In every car I ever owned, I run the AC all the time and never had an issue with mildrew in the system.

vmulla | 29. august 2019

Please refer to the reasons in my original post on why I think there's a software fix for this problem.

derotam | 29. august 2019

No real problem with your post except a few comments...I believe that the mildew/vineager type smell is due to wetness sitting in the A/C system after turning the car off with no fan running to dry it out. I do agree that a software fix can address the drying out issue.

However, at least in my situation, I believe there was an actual chemical smell at the beginning of my ownership...that did go away before the current smell I have. I don't believe that a software fix had anything to do with my initial smell issue going away. I say this because I got my car in late September 2018 in northern VA. I don't think I actually used the A/C in my car until Spring 2019. So I would say that SOME people's initial smell issues that went away on their own, may actually have been a temporary chemical smell from manufacturing. Funny thing, it smelled like RTV sealant...which has a Vinegar type smell.

I also don't think people at SC's are lying as much as just being misinformed or coming up with their own theories, same goes with owners..there is a lot of misinformation going around, or just information that has not been proven. A lot of people try to link their smell going away with a software fix but I don't think I have seen a definitive statement of when EXACTLY it was fixed in the software.

jjgunn | 29. august 2019

The software "fix" is running fans after the car is parked to attempt to dry out the system.

The problem is the design -- the condensation drain needs to be designed better so ALL the condensate leaves the HVAC system when parked.

vmulla | 29. august 2019

The smell is real, and at times it is overpowering. I've had a bit of back/forth on the forum on about what it is, and what it isn't - reasons for it, theories, validity et all.
I'm now focusing on the practical ways to manage the smell.

Let me know if I can tune the advice from that point of view. Thanks

P.S. I recall the smelly plastic posts from early on - that is different. It seems that the problem just went away with time. I did not experience it.

vmulla | 29. august 2019

Folks who visited the service center and paid for the service, you'll notice I did not suggest a service center visit to take care of the problem.
My opinion is that this was Tesla's problem to fix, and it was wrong to charge the customer. Which is why I didn't suggest taking the car to Tesla.
Since some of you have gone through the entire episode, I will be happy to adjust the content of the post based on your feedback.

tcandmm | 29. august 2019

Hi, I had my car recently serviced at SC and would certainly like to keep the bad smell from coming back, but I'm confused about the steps to take, do I run the system on fan only (AC light switched off), or AC on with recirculation for the final few minutes of driving before exit the car? Normally I always run my AC with recirculation on, does that dry the system?


lbowroom | 29. august 2019

"the condensation drain needs to be designed better so ALL the condensate leaves the HVAC system when parked."

Sounds good in theory, how is that accomplished in any vehicle?

Frank99 | 29. august 2019

vmulla -
Thanks for starting this thread. I think you've done a good job of summarizing everything known so far.

tcandmm -
Turn off the A/C a mile or so before you get home. That will allow warm air to get blown past the evaporator, drying it.
Recirc will tend to reduce the amount of condensation on the evaporator, but I'm not sure that will help reduce the problem; whether the evaporator is just slightly moist, or dripping wet, it's still wet enough for bacteria/fungus/mold/mildew to grow. Completely drying the evaporator is the solution.

IntelSPE | 29. august 2019

Helpful post for people having AC smell symptoms.

Frank99 | 29. august 2019

lbowroom -
When I looked at the evaporator and drain, it appeared to me to be well designed. The drain is a large diameter, very short, and has positive pressure blowing air/moisture out. I don't think there's any problem there, other than perhaps a small percentage of cars with an unusual blockage (gunk getting past the air filter when it gets changed, spider webs, etc).

I believe the problem is due to moisture ON the evaporator core. There's not much you can do to get that water off the evaporator core, other than to let it evaporate by having air blow past it. It'll be a very small amount of water (large amounts of water simply drip off and out), so it shouldn't take much airflow or take very long to dry it off. Evaporating is a way to get the condensate to leave the system.

lbowroom | 29. august 2019

I agree Frank. It's a tightly spaced coil that water clings to. Naïve to make a blanket statement that it should be designed to not stay wet. I love analogies so to me its like saying that cars should be designed to not crash.

Mikael13 | 29. august 2019

4,288 miles only and yes, the smell became unbearable. Had SC appointment today and cost me $75.47 out the door to have filters replaced and system deodorized. The SA and tech mentioned that more incidents have been brought up since a couple of updates ago, and they mentioned that a fix is in the works. Not sure if that’s accurate or true. A couple other Model 3 drivers who came for their appointments had the stinky problem as well and were there specifically for filter replacement/deodorizing. I’m in NorCal (Rocklin service center)

gmr6415 | 29. august 2019

@Frank99, "The drain is a large diameter, very short, and has positive pressure blowing air/moisture out."

Did you find a way to validate that while the car is moving? The real test would be does it still have positive pressure at the drain at 70 mph on the highway? Sitting still on the driveway doesn't simulate what is happening while going down the road.

The area in front of the bulkhead where the drain comes out could very well be disturbed by turbulence while moving.

Frank99 | 29. august 2019

gmr6415 -
We're getting a bit off the topic of advice for managing AC stink, but I think understanding what is happening is also useful.
I'm really not concerned about what happens while driving because:
1. It's cold in the evaporator, so nothing's going to grow. The microorganisms that cause the stink likely only grow when the car is parked and the evaporator temp climbs to ambient.
2. Once you stop at an intersection or at home the positive pressure, large diameter, and short length of the drain are going to conspire with gravity to empty out any water that has collected in the evaporator box if high pressure in that area was preventing it from doing so before.
3. If the box didn't drain while driving, people doing 3 hour trips in hot, humid Florida would complain about wet floor mats as the evaporator box fills and overflows onto the floor. Haven't heard one of those complaints.

Living out here in the desert (Phoenix), I've noticed over the years that the stink in various cars is most pronounced in dry months - May, June, early July - and reduced/eliminated in humid months (late July, August). I've always explained it to myself as the increased condensate in the humid months rinses the microorganisms off the evaporator, where in the dry months there's enough condensate to moisturize the biofilm and let it grow without washing it off. I give that explanation about a 20% chance of being right; but I'll stand by the observation.

vmulla | 29. august 2019

Making edits to the OP

changing this

"Others are running the heater on, some others or running the AC with recirculation on - they’re all basically trying to dry the system out. So, whatever your common sense tells you will work to dry the system out. This should get rid of the smell a little bit without opening anything on your car."


"Others are running the heater on, some others or running the AC with recirculation on - they’re all basically trying to dry the system out. The most popular advise based on forum posts is to run the fan only for a few minutes after each drive with the AC OFF - simple, effective. This should get rid of the smell a little bit without opening anything on your car."

Atoms | 29. august 2019

Tesla really needs to evaluate over a wide range of temperatures and dew points the drying rates in an environments chamber. They. An optimize the software to assure dry coils at the end. It would also be good for them to consider anti fungal and anti bacterial coatings like silver or EPA approved organic chemicals with persistence on the coils as manufactured.
Just hoping that Teslas cleaning and software updates make it disappear.

aptwo | 29. august 2019

@vmulla, I took mine into the SC and they cleaned the evaporator for free. Under Pay Type it says "Good will - service"

Jolly | 01. september 2019

I broke one of the clips trying to open the side cover, be gentle when pulling out the cover. I followed the steps and it is not that hard to do this cleaning.

gmr6415 | 01. september 2019

@Jolly, I lost a clip dong mine. I have clips on order. They are only $0.15 each.

Tesla part number 1067403-00-A

gmr6415 | 01. september 2019

@Frank99, there are plenty of common micro organisms that can grow in cold temperatures. Just ask any grocery store chain or Blue Bell Ice Cream.

Just to name a few: Listeria monocytogenes, Yersinia enterocolitica, Aeromonas spp., Plesiomonas shigelloides, Pseudomonas spp., and moulds such as Penicillium and Cladosporium spp.

cmichael | 01. september 2019

@Mikael13, how did you only get charged $75.47? Most people are reporting around a $190. Can you post any specifics from your invoice to help clarify?

For others who were charged more for AC filter replacement / cleaning, can you provide any specifics from your invoices to compare?


vmulla | 04. september 2019

I'm just returning from Tesla service center at Tyson's Corner.
I asked the advisor about this issue. He said it was fixed and demonstrated the fix. He put the car's AC in auto, drove forward a small distance, stopped, got out - the fans were still running after he got out. He said the fix was to keep the fans running for a few minutes after the passenger gets out to dry out the evaporator coil.
You can try the steps above to see if your car shows the same behavior. It showed that behavior for me.
He said the fix was in 2019.24.x

Thrillion | 04. september 2019

SC just rescheduled my appointment for smelly AC due to part availability. Not sure if it was for filters.
Would be silly to change out the filters if some reports don't include new filters and a clean smelling car.
Could there be another part needing replacement?

derotam | 05. september 2019

Just so everyone knows from my experience... between 2019.20 and 2019.32 there is no change in the operation of the hvac/fans after you get out of the car and it auto locks. This is with the hvac set on auto and having been actively cooling before getting out of the car.

vmulla | 05. september 2019

What is your observation at 2019.20.x that is consistent with 32.x?

Mikael13 | 05. september 2019

@cmichael - sorry I am not familiar on how to share a link to show you. You can confirm if you call TESLA SC in Rocklin, CA.

vmulla | 05. september 2019

Sidebar discussions aside. The original post still makes sense, and I stand by it.

michiels.evan | 22. september 2019

I made a video on how to fix this... quite easy...