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I don't have the problem. My car is a 2002 525i. Carfax showed that it's been registered in Hawaii its whole life. One can assume the AC has been used year round for 7 plus years and the heater more than likely never used (OK, never say never, but at most maybe a few times). I do notice that the AC drains very well when it's parked and the AC is running.

I'm posting this to help, really. Did BMW redesign something in later E39s? Not having the problem, I really haven't read up on this subject to know if it affects "facelifted" E39s.

Here's hoping mine doesn't develop the problem. That would not be good, especially in Hawaii!
 

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Seek to understand,^Value
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Discussion Starter · #22 ·
I don't have the problem. My car is a 2002 525i.
Mine is a 2002 525i also. And boy oh boy, does it have that dank stank!

I've learned the 'tricks' to avoid the stink but that doesn't mean I enjoy it.

- I've run the heater, in the height of summer, for fifteen minutes (presumably that cooks the bacteria, mold, and fungi and boils off the pooled water)
- I've sprayed disinfectant in the ductwork and onto the cooling fins of the evaporator
- I've replaced the air filters numerous times
- I've turned off the A/C ten miles from home to let it dry out a bit

I never did find the hoses that might be clogged so I've still gotta do that though!

And, I've never located how/what to wire to keep the ductwork open.
 

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Mine is a 2002 525i also. And boy oh boy, does it have that dank stank!

I've learned the 'tricks' to avoid the stink but that doesn't mean I enjoy it.

- I've run the heater, in the height of summer, for fifteen minutes (presumably that cooks the bacteria, mold, and fungi and boils off the pooled water)
- I've sprayed disinfectant in the ductwork and onto the cooling fins of the evaporator
- I've replaced the air filters numerous times
- I've turned off the A/C ten miles from home to let it dry out a bit

I never did find the hoses that might be clogged so I've still gotta do that though!

And, I've never located how/what to wire to keep the ductwork open.
OOPS-yeah probably could have seen that under "mein auto".:eek:

WHen you run your AC and the car is parked do you see a puddle of water running from under your car? Give it 3 minutes and you should see it. If not it could be clogged, depending on how hot and humid it is.
 

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"Clunker" *****
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I don't have the problem. My car is a 2002 525i. Carfax showed that it's been registered in Hawaii its whole life. One can assume the AC has been used year round for 7 plus years and the heater more than likely never used (OK, never say never, but at most maybe a few times). I do notice that the AC drains very well when it's parked and the AC is running.

I'm posting this to help, really. Did BMW redesign something in later E39s? Not having the problem, I really haven't read up on this subject to know if it affects "facelifted" E39s.

Here's hoping mine doesn't develop the problem. That would not be good, especially in Hawaii!
No problem in my 1999 528. If I use the AC in the spring or fall, I generally shut the AC down a few minutes before I get home so it doesn't fog up the interior when I turn the heater on at start-up. Every other car I've had required the same treatment.
 

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There are actually two drain hoses: one on each side of the trans.

I guess I'm the Lucky One here. We have very low-humidity summers here, so I get very little condensate dripping out. When I do smell something, I pull the cabin filters, and, with the blower on low, not recirc, I hose down the intake ducts from under the hood with Lysol spray, and let it set overnight.

I suspect the real problem is that the mould grows on the evap, which is moist from the A/C operation. That's why the foam stuff does the job, since it is able to penetrate the fins.
 

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No A/C stink anymore! Change the cabin air filters and make sure they are not the cheapies, but the charcoal activated kind. I have has the car 3 years, and have changed the cabin air filters 4 or 5 times, because initially it smelled. No smell now at all, so I will just get on a yearly routine with those. I do sprinkle in a little baking soda as well on to the filters. Another thing, make sure that your cabin air filters are dry. If they are not installed correctly and the covers not attached, rain water can seep in and make them damp. As they say, "ask me how I know......" Keep the small rubber drain hoses clear of leaves and debris --these are located to the bottom of each plastic filter housing. I use a plastic straw to clean them out. It's flexible and something I had around the house. Run the A/C in the winter to keep it lubed up . I use it not only for cooling, but to get rid of moisture even in cold weather. I do let fan run after I turn A/C off--but not for 10 minutes, and not every time. I dunno, maybe because I use the heat during the winter, that somehow dries out whatever causes the damp smell? All I know is that the CC in this car is fantastic for the most part. I really like the fact that I can fine tune the dash vents using the center dial--seems like a small feature until you freeze/bake your face off in another car! Oh yeah, I also replaced FSU/FSR last Spring. Best of luck resolving this stinky problem.
 

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Seek to understand,^Value
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Discussion Starter · #28 ·
No A/C stink anymore! Change the cabin air filters
Can you show me in a picture WHERE these "cabin air filters" are?

The only filters I know of are the two that are in the engine compartment along the bottom two corners of the windshield. Are you talking about those filters? (They don't seem to have carbon in them???)

Keep the small rubber drain hoses clear of leaves and debris --these are located to the bottom of each plastic filter housing.
Again, can you show me what you mean by these drain hoses?

Do you mean the drain hoses that people say come out of the BOTTOM of the car (meaning we have to lift the car to see them)?
 

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Seek to understand,^Value
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Discussion Starter · #31 · (Edited)
With the summer in full swing, the AC stink problem arises again.

With another year under our belts, is this the recommended set of ac-stink problem statements and recommended solutions?

STINKY AC PROBLEM:
- It's first, and foremost, a BMW A/C downsize design problem (too cramped for proper ventilation of evaporator coils)
- The design problem allows food (dust), water (evaporator coils & ducts) and microbes (stinky poo) to coexist
- Resolution entails design, maintenance, & behavioral modifications (reduce the water, food, and stinky microbes)

DESIGN MODIFICATIONS: (Note: These are draconian)
- Cut hole in driver right-foot panel so you can spray germicide directly on evaporator coils (kill the stinky microbes)
- Drill a larger hole &
clean the evaporator fins with a toothbrush (less food for the stinky microbes)
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Unkink the E39 evaporator duct (behind dash) by wiring the damper (less water for the stinky microbes)

MAINTENANCE MODIFICATIONS: (Note: These are judicious)
0. Reseat the two cabin-air micro-filters in the engine bay (BMW says stink can get in if they're not seated well)
1. Check if there is water normally draining from under the car after running your AC on a hot day
If there's no water pooling on both sides of your parking spot ... then ...
2. Clear the two undercarriage drain tubes any way you can:
- Some people suggest you snake a coat hanger past the multiple elbows to the evaporator coils to unclog
- Probably more reliable is to attach 13.5mm to 14.0mm OD plastic tube to both drain hoses & blow out obstructions
3. Unclog the drain holes & tubes in the two engine bay micro filters
- Some suggest snaking a six-inch length of coat hanger into the holes from the cabin filter downward thru the rubber drain hose
And, for more serious cases of BMW stinky AC:
4. Replace both engine-bay cabin "micro" filters (less food for the stinky microbes)
If eliminating water has been done, yet the stinky-AC microbes are still active ...
5. Spray tons of disinfectant in the air intake or directly onto the evaporator (through the drilled hole method).
- You'll need tons of germicide because it's not a direct shot to the evaporator coils from the air intakes
- Or try somehow to spray germicide upward hopefully onto evaporator coils from the undercarriage drain tubes
- While you're at it, spray ample germicide in central cabin vents (hoping some germicide lands on evaporator coils)

Note: The undercarriage drain tubes are apparently hard to remove for direct access to the evaporator coils; and, worse yet, they have a 90-degree elbow and 1-foot horizontal run, so, they're difficult to get a coat hanger into and even more difficult to get germicide up far enough to coat the evaporator coils.

BEHAVIORAL MODIFICATIONS: (Note: The fact we have to do this is ludicrous)
- Each trip, turn the AC off five miles before you arrive at your destination (less water for the stinky microbes)
- Park slightly nose upslope presumably so horizontal drain tubes drain better (less water for stinky microbes)
- Once a day, turn the heat up to 90 degrees and cook for 15 minutes (kill the stinky microbes)
- Set the AC to 72 degrees, "Auto", "Snowflake", & "
Circle without the A" (basic setup but doesn't help much)

Note: Yes, it's crazy to own a "luxury BMW" and then have to babysit the AC by turning it off or turning the heat up to 90 degrees in the hot summer so that it doesn't embarrass you with AC stink when you have a customer in the car; but, what else can you do?

 

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Freude am Fahren
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Drove my car a few weeks ago; really needs some a/c disinfectant :(

Thanks for the procedure, bluebee. I'm not f'ing turning off the air every time I stop the car :p but the other stuff will happen, if slowly***8230;
 

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Great! All this talk about stinky A/C systems and now I'm starting to smell some funk in mine. Thanks guys! Got me all paranoid so I'll be doing a complete check this weekend.
 

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I have a smell when the car initially is started with a/c running, but it rapidly goes away, so I am not too bothered by the problem. However, it's clear that some are greatly troubled. So, I just took a look at mine, partly out of interest. Here's what I found and suggest:

1. The drain tubes run on either side of the transmission (on my auto), towards the rear of the car. They actually run approximately horizontally for about 12" before the end of the tube is gound. On my car, the tubes actually end beyond the rear of the transmission and rest on top of a cross-member of some sort. That's probably why they are difficult to spot. I tried taking pictures, but the're not good pictures.

2. At great risk to health, I decided to see if they were blocked. Rather than poke a rubber pipe with wire etc, I stuffed a plastic tube about 1 inch up the drain, so it sealed nicely. If you try this, it needs to be 13.5mm - 14.0mm OD tube. That fits OK. I then blew down the tube.

3. On the LHS, there was a bubbly gurgling sound, like air bubbling through water and the end of the drain was wet also. On the RHS, the drain appeared dry and there was no bubbling sound, just air flow. Both tubes appeared unobstructed overall. You can actually hear all this inside the car if you get a long anough tube. My doctor assures me that Legionalla clears up quickly and not to worry.:yikes:

4. Observation: If, like me you park nose down on a slope in your driveway etc, then at the end of a journey, there will be water trapped at the elbow of the horizontal drain, unable to drain away. This could be one source of water accumulation and smell.

5. Suggestion: I assume these drains vent direrctly into the evaporator assembly. So, instead of drilling holes etc, why not shove the disinfectant spray directly up the drain holes from underneath the car? Once you know where they are, they are very easy to access, without lifting the car
 

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And another thing.....

In the original post, I reckon part No 5 is the horizontal drain that runs under the car. part No 17 is the hidden pipe that runs vertically to connect to No 5 and this one is hidden from view, inside the car, and runs directly from the evaporator. Correct?

Also, the drain pipe under the car is cunningly bolted in place, so it cannot be easily moved.
 

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BMW is too arrogant to believe their duct work is faulty.
I would believe that, my 1983 E28 533i had the same problem. It had a A/C system that was not automatic so I shut it off a mile or two before getting home. It helped. I also Lysoled the ducts but that was only temporary.

On the 2002 E39 540i, the stink is not consistant. Sometimes it does and sometimes not. I would love a solid fix for this issue. The area of the car that houses the A/C system is packed tight and wonder if the fix would be reasonable to attempt even if you could figure out that the moisture is pooling. Could it somply be hanging on the evaporator coils?

Keep us posted!
 

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Discussion Starter · #38 ·
Stinky AC DIY solutions (adding to the list)

I stuffed a plastic tube about 1 inch up the drain ... I then blew down the tube
Excellent tools/procedure to add to the stinky-AC DIY!

On the LHS, there was a bubbly gurgling sound, like air bubbling through water and the end of the drain was wet
Interesting observation. Would be interested to see if, say, after a week after you blew the LHS drain out, if the water returned or if the stink went away.

Legionalla clears up quickly
OMG. Legionella pneumophila lives in AC water and invades the lung! I hope you never sucked it in!

water trapped at the elbow of the horizontal drain
Another interesting potential solution; park the E39 nose up! (I'll add this to the list of potential stinky AC DIY solutions)

why not shove the disinfectant spray directly up the drain holes from underneath the car?
Yet another new and interesting potential stinky AC DIY solution! The whole problem with spraying the vents with germicide is that the microbes are reputed to live in the evaporator coils so very little (if any) germicide actually lands where you need it on the evaporator coils.

Access to the evaporator coils is the reason for cutting the hole but, as you note, cutting the hole is a pain so most people probably don't go to the effort.

However, if we can access the evaporator coils from the drain tube, then that might be effective. But I'm confused 'cuz you said the drain tubes had a one-foot horizontal path so I think you are suggesting temporary removal of the rubber drain tube (right?).

Is this the suggested procedure:

a) Lie down under the car and reach under to locate the 2 drain tubes
b) Remove the two drain tubes from under the car (probably by pulling off?)
c) Spray germicide directly directly up into the opening left by removal of the drain tubes (so that you can spray the evaporator coil and collection pan directly)
d) Blow throught each drain tube to ensure they are not clogged
e) Return the two drain tubes (presumably by pushing back into place)
 

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Would be interesting to know why some of us have this problem and others don't. For those who have the problem: Do you always have your air control on recirculate? My nephew did that and his truck always smelled like a cave. I tried to get him to put it on the fresh air setting but he was convinced that it (heating or cooling the air from outside) would hurt his gas mileage and performance
 

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No stink in mine. ac vent tubes appear to be open, I see water when I back into my driveway each day which places the nose down. I also use charcoal activated cabin filters and keep the drain hoses clear in that housing. Run my ac the majority of time in re-circ, but occasionally with outside air when it is not too hot outside.
 
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