Tivan

No. AC is almost exclusively ON. The only time i turn it off is on summer days after prolonged drive to heat up air ducts and evaporator specifically to avoid these issues. I forgot to mention one more observation. This smell appears only when re-circulation is enabled when car engine is almost at the temperature. Meaning, If I turn it on while car is "heating" (water temp about 60 C and lukewarm air) then it does not smell. As the water gets toward 70-80 and air starts to blow hot, then this issue appears. Changing cabin filter yesterday did not help.

I have been changing cabin filter on regular basis. If its that filter that is causing the problem, how come the smell only appears when airflow does not go through it? I use those AC sprays every summer, usually those from Sonax. But they do little to nothing. For the sake of me getting to the bottom of this, i just changed cabin filter few minutes ago. Yes, old one was a bit dirty, but nothing alarming. I always but carbon filters or better, depending on current price when I am shopping.

Where I live there are still a lot of older cars that really emit a lot of black smoke. Some buses do the same. And I often drive my kids (youngest one is 1 year old). That is the main reason. Then there are various different smells in different parts of the city or around it (mostly factories etc.) I am not using it all the time, but I do use it often.

Thank you for the reply. I vacuum the car on a regular basis, especially the carpet on the driver side. There is no smell like this in the car. Also I did suspect this in the past so I tried to stick my nose as close as possible to that area but I smell nothing. I did purchase a vacuum for cleaning carpets so this spring/summer I will do that as well. In the next few days weather is going to be warmer where I live so I will definitely investigate this area a bit. I am also thinking to sanitize only this footwall intake part of the vent system. I just don't get it why it behaves like this. My car is really tidy and i take good care of the interior.

Hi to everyone. I have a specific issue with ventilation smell, and I am at lost, so wanted to ask for an opinion. In short: Ventilation puts out ash/dust like smell only when recirculation is ON in winter time when heating. Longer version: About 2 or 3 winters ago I noticed the same problem. When I drive in winter with heating on (ac also on and heating works fine) If I turn on recirculation to avoid car fumes in traffic I get this strange smell…reminds me of what you get from a bagged vacuum cleaner when full, or also like emptied (but not washed) ashtray. Anyway, next spring I decided to detail my ventilation system. Cleaned all the ducts with alcohol and AC disinfection spray (vent grills off so I could access the tunnels). Also tried to spray as much as I could on evaporator via center vents with grills off. Changed the filter at least once a year but usually twice. Lasted fine until this winter, same issue. Now I do not want to drive remaining months with smell but even worse, the cleaning I did back then was really a pain in the ass DIY job. So if possible, I would not want to repeat it every 2 years. What puzzles me is why this only happens if recirculation is ON. I imagine in that case air no longer passes via the cabin air filter so that falls out of the equation. But even if it did pass through it, I change it regularly. What else could it be there that would cause it to smell like this in this particular case?

Glad I could help. Enjoy the car and safe drive!

That is correct, it controls the "mix" of cold and warm air in order to make the correct temperature. There is one on each side (driver/passanger). No idea why would it work better when rotated 180 degrees. If the rotor moves up/down, then maybe when you turn it upside the brushes get better and more reliable contact and hence it rotates nicely? But this is just a guessing game at this point.

I assume you put back the white gear pinion that fell out, just for the sake of not having another set of issues beside the blower. Re blower, sounds like it's on its way out. It behaves the same outside the car (if I understood you correctly) as it is when its in place and oriented the way it should be. And when opposite, it works as usual and does not get tired. This would indicate (to me at least) that there is something physically wrong with it. Maybe try and clean and lube the spindle? Also, check there is nothing that could physically obstruct the operation of the motor. Or give it to someone who has the bench and expertise for motors to take a look at it.

This is the temperature flap control motor. The part that fell out is one of the pinions.

I have the same thing, same noise, same car with 5 speed manual...i think its been like this at least 30k kms. Was planning to change gearbox oil but I never got to it. I am not planning on taking it apart or anything, first I will change the oil then we will see. I was also suspecting its gearbox as mine is acting up when downshifting sometimes, but not sure. I have watched a russian mecahinic explaining in video a while ago where he said those M5 are notorious for breaking unless you change oil. Supposedly you should do it before 100k on the clock. I guess I am pushing my luck at this point at 119k. But then again, you are at well over that mileage so I may still have time...

I wish I knew. Any potential point of contact I could see I treated with silicon, with heat-resistant tape that has a small layer of foam on it, then also a few other improvisations. I also tried to isolate any friction between that lower trim and upper lighter trim as much as I could without results. So I am at lost at this point. I just don't understand how this happens after years of silence. I understand that squeaks and other similar sounds in a car can develop with time as the materials age or something gets loose. But most often due to constant stress and movement (like door trims). However, in most cases when you find the cause of the issue and tighten the loose part or treat the area with silicon or what not, things get back to normal at least for some time. Not here. And there is nothing that can be loose. Well, anyway, maybe I get lucky and someone who dealt with the same problem reads this thread in the near future. Until then, I will most likely try the same things again and again until it miraculously gets solved.

One year after update - damn squeak still there. There is no thing I have not tried. Various tapes, silicon sprays, cloth....nothing helps. IT does not make any noise during winter time. But as the temperatures start to raise these days where I live, sound is back. It's so damn annoying that I am thinking of pulling this thing out and drive without it. The only concern (a legit one) is that my foot will then be very close to a hot pipes. During summer that thingy gets very very hot... What I cannot fathom is that squeak can happen when I accelerate from full stop. How is that there is any or that much movement of these parts to provoke this squeak? I mean, I do need to apply solid pressure with my hand to provoke it.

Ash residue is the value you need to observe in relation to when to think about replacing the entire DPF. Soot value is normaly at 24g when active regen is started. On your car for some reason it was unable to do that until now. Having this oil ash residue at only 19g at your mileage raises suspicion if that value is correct or not. If it is then your filter most likely is not for change. Although I am unsure how you can determine if it's correct or not at this point, educated guess from me would be that dpf was cleaned at some point and then was reset. If that is correct, what you now observe is clogged DPF that cannot perform active regen and needs forced one or replacement. That would be more appropriate state for given mileage of the car.

😁 I imagine I would discover the problem in a different way if it was dead body in there...

I almost never turn of ac, summer or winter.