my e46 (IHKA) has a damp, musty odor from the air vents when in fan only mode after the A/C has been on. Seems to be slightly worse when outside air is selected, but still noticable in recirculate mode. I've read many things on various forums about this, and tried every method suggested to try and combat this, plus a few more things. Nothing has worked, and I'm completely out of ideas. Here's what I've tried so far: - replaced microfilter - sprayed down evaporator with lysol sanitizer & modified garden sprayer - run a can of wurth a/c & heating system cleaner through the system - used a wurth odor eliminator fogger aerosol with the a/c on recirculate. - removed the blower motor, cleaned the fan blades, cleaned the housing, sprayed the evaporator down again with lysol. When the A/C is on, and outside air is selected it smells ok, no real odor either good or bad. When A/C is on, and recirculate mode is selected it smells of one of the cleaners I used. No idea which, but it's a pleasant smell. In either outside or recirculate mode, as soon as I switch the A/C off leaving fan only, I get the damp smell. The only other idea I have is taking it to the dealer to have them perform the evaporator spray down. They should be using the same stuff I did, but possibly with a slightly more powerful sprayer. I'm dubious as to whether this will help at this point. If anyone has any suggestions, (no matter how much of a long shot!) I'd really appreciate it. I'm finding myself not enjoying driving the car as I'm constantly messing with the A/C controls trying to see what does and doesn't produce the smell. Thanks for any advice.
OK. You asked for a long shot. I too went through most of the steps you detailed with only temporary results. My final solution taken several years ago was to MECHANICALLY disconnect two of the duct door stepper motors from the door linkage. I then MECHANICALLY locked the door flaps into the fresh outside air position. Within a couple of weeks the smell was gone, never to return. Heresy? Yeah, I guess so. But for our climate (high dry desert) and usage (mostly 3-4 mile short trips across town) it has been quite effective. IF you elect to try this, note that I emphasized MECHANICAL disconnection. Under NO circumstances electrically disconnect the motors. You'll cause unwanted error codes in the system. Good luck! (BTW the car is a 99 528iA.)
Thanks for the suggestion, that makes a lot of sense. I noticed when I was spraying disinfectant into the blower housing that it wasn't actually on outside air mode until the temperature was set in the mid-80s, (mid-90 degree outside temp) despite the climate control being set to outside air. Did you leave the flaps set in this way permanently, or reconnect the linkages once the smell had gone away?
Just in case you didn't do the last step after spraying out the evaporator I thought I would include this! Good Luck! Straight from Bentley Manual... Mildew in the IHKA housing and in the evaporator fins can cause strong odors. Working under right side of dash, remove blower resistor pack (attachment photo arrow). Poke a spray wand through IHKA housing opening and spray commercially available cleaning agent on evaporator. Move wand back and forth to cover evaporator fins with liquid. Allow 5 minutes for liquid to drip through evaporator drain. Start car and run heater and A/C at maximum power for 5 minutes to dry out evaporator.
Thanks for the info, it's much appreciated. The sib mentions the 5 minute drying but doesn't mention the temperature setting so I may try again with it set on full heat. My other thought is this - the BMW sib says to connect the spray wand/tool to a compressor supplying no more than 140PSI. I'm sure the tool reduces this but I wonder by how much? I was using a pump-up garden sprayer with the wand modified to spray at a 90 degree angle. I'm wondering whether the BMW tool sprays this stuff under much higher pressure to better penetrate the evaporator.
