Mildew Smell

I had a similar issue with a previous car. At the recommendation of a member of a BMW forum, I bought Wurth A/C & Heating System Treatment. Easy to use, and I had the car for 2 years afterwards with no issues:
Wurth A/C & Heating System Treatment 6 oz.

 

Danny,
Do you have an update for your mildew smell car service months ago? Mine is just starting... Did the Lysol resolve or the dealer visit -if so what did they do?
thanks~

 

I was always told to run the a/c with outside air once in a while to run fresh air through the "condenser".

This advice was given from the owner of an a/c shop.

By keeping the a/c on recirculating, the air gets "trapped" in the condenser which can cause mildew to grow.

I have also used the Lysol method on occasion which has worked.

Also, running hot air will help kill off the mildew. Problem is, you have to run it on high for a while.

I hope this helps.

 

yep, thats what you need to kill those ugly things in your vent system

 

Mildew in the A/C evap and lines is a much more common problem than most people realize. Running the hot air with a/c on helps a little. You could also try blowing a hair dryer into the vents if you suspect the moisture is at the vent level.

 

Alexma identified the root cause of the mildew smell problem - excessive use of the a/c in RECIRCULATION mode. Recirculate is the default "Air Inlet Mode" for the Gen III with automatic climate control in order to increase MPG. The a/c has to run less in recirculate mode to keep the air cooled and dehumidified; however, the mildew smell is a result. The mildew smell is not only unpleasant; it is actually unhealthy.

If you want to prevent the mildew from occuring, you have to run the a/c in fresh air mode and use recirculate mode only occasionally. This is difficult to do when recirculate is the default mode because you have to constantly think to push the fresh air button when you turn on the a/c or restart the car.

Good news however, the default "Air Inlet Mode" can be change to "Manual" by the dealer which will cause the a/c to come on in the mode it was last set, i.e. fresh air. Attached are the pages from the service manual for customizing settings. Note that in addition to the air inlet mode, I also had the "Compressor Mode", "Foot/DEF Automatic Blow Up Function" and "Reverse Warning Buzzer" modes changed. The dealer charge for these changes was $54.00, but worth it in my opinion because everything now works the way I want and I no longer have any unhealthy mildew or smell.

 

My experience is different than what you stated in the red highlighted paragraph above.

I always keep my car in air inlet mode, unless I get behind a stinky diesel truck or smoke machine of a car, since I'm more concerned about fresh air supply than any minor MPG hit, and I never have to reset it. I always have A/C on, and the doc you attached is not inconsistent with my experience. It seems that the default setting is only applicable when the A/C is turned on (not when the car is powered up with the A/C having been on the least time it was powered off).

 

I suspect the reason your a/c stays in fresh air mode is because you always have your a/c on as you state above. My a/c is only on, mostly in the summer months and occasionally in winter, when I need it and I usually turn it off before I turn off the car. So having the "Air Inlet Mode" changed to manual probably isn't worth it for you, but it is for me and others who operate their a/c as I do. C'est La Vie.