[bluebee]

In this water-drainage thread, pleiades brings up a good question.

There are (at least) three sets of drain hoses or ducts in the E39 (as shown in the diagram below reproduced from this thread).

But, there is only one evaporator (right?).

Up until now, I "assumed" that the two undercarriage drain hoses were for the "evaporator" water; however, they are widely spaced apart and one would think a single hose would suffice for a single evaporator.

Plus, there are two more sets of drain hoses (at least); which makes for six drain hoses in total.

So, the question arises:

What exactly do the three sets (six drains in total) of drain hoses below drain?

 

[LarryBrown]

Why do the clogged microfilter drains cause odor?

Man this is a weird thread. So many posts, so much time, so much intensity, and almost no hard information.

It has been observed that 1 or both of the following factors materially contribute to the problem: clogged microfilter drain hoses and leaking microfilter ductwork. One or both of these problems also cause(s) fog on the windshield during a carwash. That's the closest thing here to hard proof of what causes the problem, but no one picked up on that with further digging. Here's a couple of questions:

How did those problems cause the fog on the windshield at the carwash?
How could clogged drain hoses there cause the odor problem?
How could the leaking ductwork cause the odor problem?

Interesting that the word "rain" does not appear even once in this thread.

Here are some guesses from me:
If the drain hoses are clogged, and rainwater gets into the housing and dampens the filters, that would certainly seem to cause the filters to get musty and cause odor in the cabin. In such a case an inspection of the filter might show them to be obviously wet, and replacement of the filters would cure the problem at least until the next rain/carwash.

If the ductwork is leaky, then the blower is trying to suck in air through the filter via the ductwork. It's easier to suck air in through the leak than it is through the filter, meaning that a lot of air gets pulled into the system without going through the filter. That would get more dirt/dust into the system than desired but I wouldn't think it would be a lot of dust unless driving through dusty areas. In such a case replacing the filters might improve the odor because the new filters would have less airflow resistance than did the old ones.

 

[bluebee]

Just for the record, it looks like the X3 E83 (2004 - 2010) side of the house also has this perennial problem with gym-sock smelling air conditioning:
- Stinky smell from HVAC

 

[shenecke]

Not this thread again now that it's getting hot. Just keep the drain tubes open by keeping them clean. New cabin filters and blow them out with some compressed air once in a while!

 

[bluebee]

Just keep the drain tubes open

Now that I understand and have solved the problem to my satisfaction, that's my advice also.

In fact, this is what I wrote back to the OP of that thread:

There are many who say spraying the evaporator coils work. In the E39, those people drill a half-inch diameter hole in the drivers right foot kick panel to access the evaporator coils.

Others modify their habits, by essentially doing things that 'dry' out the evaporator coils five or ten minutes prior to shutdown (e.g., they actually turn on the HEAT five minutes before arriving home).

Still others unclog the two undercarriage drain hoses; and others unclog the underside of the two cabin-air filters. Most replace their cabin air filters and clean out the grime below them. This seems to work the best (although modifying habits also works).

Some even resort to modifying the vents; but we can't find anyone who can provide a reliable DIY so consider that a purely anecdotal solution.

 

[Meaux]

I've never had this problem either... I run mine on 'AUTO' @ 70deg. and never touch it... In the winter I just turn off Compressor...

Looking at the 'Parts', when all else fails, my first guess would be drilling a hole in #17 tube @ the bottom of the Elbow...

Anybody know how to set the A/C in 'Recirculate' all the time? Not a big deal, I just get tired of doing it manually... It just makes sense to cool the air thats allready cool, (and de-humidiified) than to pull out the Humidity (water) from Hot outside Air... Did I just stumble on to something???

 

[bluebee]

I run mine on 'AUTO' @ 70deg. and never touch it

There is a thread on 'how to set up the AC once and leave it there forever' (or something like that.

Gimme a sec' to find it in the bestlinks (using /ac(F3)) ...

Ah, here it is (see the part in red I highlighted for you):

How to learn about (1) and set up your air conditioning (1) (2) & how to replace the activated charcoal cabin air filter (1) (2) & what cabin filter to buy (1) (2) & cn90's inexpensive cabin filter retrofit (1) (2) (3) & cabin air filter implications for stinky gym sock AC odors (1) (2) (3) (4) & how to refill your A/C system for $20 (1) (2) (3) (4) & where to find your low pressure aircon recharge port (1) & what refrigerant PAG oil to use (1) (1) & R134a conversion information (1) (2) how to measure A C temperature (1) & how to diagnose A / C compressor knocking sounds (1) & air conditioner compressor replacement DIYs (1) or compressor rebuilds (1) or ac hose rebuilding services (1) & how to remove the IHKA air conditioning control panel to clean the circuit board (1) (2) (3) (4) with removal of MID, HVAC/IHKA, Business CD player (1), & dashboard trim (1) & how to remove the trim and bracket holding the MID & HVAC/IHKA panels (1) (2) or to replace the IHKA button (1) & how to check the IHKA sampling fan (1) & how to change OBC MID IHKA KTMP temperature from degrees Celcius to Fahrenheit (1) (2) (3) (4) (5) (6) (7) (8) & how to diagnose lack of HVAC/IHKA heater core heat with cooling system (auxiliary pump) at idle (1) & what is this thing (HVAC/IHKA solar sensor) in the middle of my dashboard by the windshield (1) (2) (3) (4) (5) (6).

 

[Meaux]

^^^ Thanks Blue, I'll check it out tomorrow, time fer Nite Nite...

 

[bluebee]

While behavioral modifications work, I prefer to modify/fix the bimmer itself, not my actions (although I swear it seems to temporarily work to run the heater on full bore for the ten minutes before arriving home!).

My stink is back, after an 18-month hiatus ... so, the combination of filter-changing and drain-hose unclogging and cabin-filter-cleaning only worked for 18 months (half of which were 'winter' months - if you can call California rainy weather winter).

So, I'm going to have to re-read this thread to find precisely what I did to get rid of the stink (I tried so many of the suggestions).

BTW, today, another poster asked about the gym-sock smell, and was told the same behavioral modification advice, but here's a slight new tack on them!
- E39 (1997 - 2003) > bad odor from a/c.. what to do?

If you really want to get rid of the smell, replace the evaporator. It might sound stupid, but thats the best way to remove mold, thats why when your few blocks from your house, your should run the blower W/O AC turned on

Also this came up in that thread:

I modified a garden sprayer and used a bleach and water solution to sanitize the evaporator. I had a slight bleach odor for a few days, but ALL odors are gone now.

http://www.bmwtips.com/tipsntricks/

Under Manintenance select 12, Foul AC Smell.

 

[bluebee]

Today, JimLev posted a very nice picture of the 540i drains for someone who had water pouring out of his interior AC vents:
- E39 (1997 - 2003) > 1999 bmw 540i

Your evaporator drains are plugged. Get under the car and stick something flexible up the drain tubes to clean them out.
They are black and located on each side of the tranny.

 

[Fudman]

My stink is back, after an 18-month hiatus ...

Mine is back too after about 9 months. And I am getting the smell during straight venting (no A/C). I only sprayed the microfilter inlets with some A/C disinfectant I got from Autozone. This is becoming an annual ritual. I think I may try something more significant this time around...

 

[chiefwej]

I have drilled the hole and made the tool to spray down the AC evaporator. I have to treat the system every three months or so to keep the stink away. Here in Tucson the AC stays on all the time, so the system never drys out. The good news is it only takes about 15 min. to open the panel, pull the plug and spray it down.

 

[Fudman]

That looks like the route to go. On BMWTips, I can't tell if the tip of the nozzle sprays forward, in a fan pattern or if it is supposed to spray at a ninety degree angle. Any thought on that? Just insert the nozzle into the hole and spray away?

 

[chiefwej]

You fold the end of the tube then cut a slit across the tube w/ a saw. You get a fan spray at a 90 degree angle.

 

[Fudman]

Thanx, Chief! Last question. Looking at the hole from the driver side, what direction do I spray (12 o'clock being up, 6 o'clock straight down).

 

[chiefwej]

9 o'clock, well really between 7 and 11 o'clock. The hole is to the rear of the car from the coils. So you are spraying toward the front of the car. I rotate the handle to spray up and down and move it in and out to spray across the width of the coils.

TIP: put zip ties just before the slit and at a point where the wand is all the way in. This will make it a lot easier to spray and will indicate when you are fully in and about to pull it out (and end up spraying all over the interior).

The best product I have found is ZEP Odor Control Concentrate. Find it at Home Depot about $10 per gallon, and a gallon lasts years.

 

[bluebee]

you are spraying toward the front of the car

I might try this spray-the-evap-coils trick myself, as I had 'thought' I had the problem resolved ...

But ... the thing is ...

I'm not 'convinced' that the 'problem' IS the mold on the evaporator coils.

It 'might' be; but then, why did the stink go away (temporarily) when I ran through the basic maintenance stuff discussed in the post from 4/15/2010 above).

So, what I'm saying is that the AC 'gym-sock' smell abated for, oh, about a year, once I did the 'normal' maintenance.

• Replaced cabin air filters (Mann charcoal activated)
• Cleaned both cabin air filter housings and drain hoses
• Checked both undercarriage drain hoses

The question is whether spraying disinfectant directly on the evaporator coils (after brushing them if possible) will lengthen the abatement period ... or not.

What do 'you' think?

PS: It's weird that we all know exactly what that funky smell is ... so what's strange is that it must be the same organism (mold?) that is causing it ... since the smell is unique ... and common to all of us. Interesting. It would be nice to have a microbiologist out there to help with the bug identification.

 

[ElwoodBlues]

...

• Replaced cabin air filters (Mann charcoal activated)
• Cleaned both cabin air filter housings and drain hoses
• Checked both undercarriage drain hoses

The question is whether spraying disinfectant directly on the evaporator coils (after brushing them if possible) will lengthen the abatement period ... or not.

What do 'you' think?

I've yet to attempt the procedure, but it sounds like it would help. I think the above list are good things to keep an eye on, and can sometimes be the root or contributing cause, but my opinion is that more often the coils or the coil housing/ductwork are the root cause.

 

[bluebee]

but my opinion is that more often the coils or the coil housing/ductwork are the root cause.

Well, I think I'll try cutting the hole ... and see what happens. I need to buy the right tools (a hole saw perhaps?).

I will also look up how long the Mann charcoal activated air filters are 'supposed' to last (how long do they 'last' on you?).

 

[doru]

Man this is a weird thread. So many posts, so much time, so much intensity, and almost no hard information.

It has been observed that 1 or both of the following factors materially contribute to the problem: clogged microfilter drain hoses and leaking microfilter ductwork. One or both of these problems also cause(s) fog on the windshield during a carwash. That's the closest thing here to hard proof of what causes the problem, but no one picked up on that with further digging. Here's a couple of questions:

How did those problems cause the fog on the windshield at the carwash?
How could clogged drain hoses there cause the odor problem?
How could the leaking ductwork cause the odor problem?

Interesting that the word "rain" does not appear even once in this thread.

Here are some guesses from me:
If the drain hoses are clogged, and rainwater gets into the housing and dampens the filters, that would certainly seem to cause the filters to get musty and cause odor in the cabin. In such a case an inspection of the filter might show them to be obviously wet, and replacement of the filters would cure the problem at least until the next rain/carwash.

If the ductwork is leaky, then the blower is trying to suck in air through the filter via the ductwork. It's easier to suck air in through the leak than it is through the filter, meaning that a lot of air gets pulled into the system without going through the filter. That would get more dirt/dust into the system than desired but I wouldn't think it would be a lot of dust unless driving through dusty areas. In such a case replacing the filters might improve the odor because the new filters would have less airflow resistance than did the old ones.

I can answer the question in bold:
the microfilter air channel (part #7 in the diagram) is not set properly in the firewall/cawling (the part that enters in the cabin), and will suck moist air. I had this happenning because the first I had the car, it was serviced by BMW, and the doehead who serviced it never put it back correctly. I fought the issue a few months looking at all kinds of hoses, ducts etc, but when I changed the microfilters and totally removed the the air channel, it was then I noticed it was not placed properly in place. It is a bit tricky to install it back. The 3 tabs have to be in, and then you will have to twist by applying pressure and in the same time making sure the air channel is square on the surface. Also, this part will eventually desintegrate due to heat. The passenger side on my car already bit the dust, and the part is not cheap.