What is going on with that A/C smell???

[Thunderguts]

I'm posting here for more views even though there is a nice DIY thread here: https://www.1addicts.com/forums/showthread.php?t=739013.

I'm trying to figure out what the hell is going on with the HVAC unit in the E82 that causes it to stink so badly. Firstly, I never drive with the recirculate feature on. I've used it maybe twice since I purchased the car, but there is a serious mildew issue somewhere in the HVAC unit. I even turn my A/C off about 5 minutes before I stop the car and put the blower on high to dry it out. I have cleaned my evaporator twice with Klima-Clean. My evaporator is not the issue. It actually looks very clean. I removed my blower motor and stuck an endoscope in there to examine it. I am 100% confident that I can rule it out as the culprit. My drain works. I flushed the evaporator with distilled water after cleaning it and the water flowed out immediately.

Here is the scenario: I turn the A/C on in the car and I get no smell. It doesn't smell when I'm using it. When I turn the A/C off to dry it before stopping a very slight smell is present at first. After about a minute or two, a wave of putrid mildew stench hits all of a sudden. Something happens after a minute to cause this. I've noticed that the A/C does funky things on its own. After turning off the car, a little flap at the top of the central vents closes by itself after about 3 minutes. Somewhere there's a flap that opens up when I turn off my A/C that lets forth this awful smell. I just don't know what it is.

Has anyone actually taken apart their HVAC unit? Where the hell is the mildew hiding? I'm going to use a couple disinfectant bombs run through the recirculate feature, but I'd rather clean it properly if I can find out where the mildew collects. As I said, it's always the same scenario. After about a minute of turning off the A/C the smell hits all at once and lasts for about another minute or two before tapering off.

[Tuxedo]

I use to get a similar smelly as I'd turn off the system. read here on 1addicts to leave HVAC on auto all the time and cured it.

[Matticus91]

Have you actually used one of those bombs yet? There are many small parts in the lines where mildew can collect, and it's not always visible. I use one of those bombs once a year, they work wonders.

[Thunderguts]

Originally Posted by Matticus91

Have you actually used one of those bombs yet? There are many small parts in the lines where mildew can collect, and it's not always visible. I use one of those bombs once a year, they work wonders.

The more I read about the bombs, the more it sounds like they don't do anything to kill mildew. They just mask the smell which is absolutely what I don't want. I ran two 1-ounce cans of Frigi-Fresh through the fresh air intake which didn't eliminate the smell either. I don't think enough is making it past the blower though. I may make a small pin hole downstream of the blower and use a straw to direct it into the system.

Oh! It looks like Nextzett makes an odor bomb that actually kills mildew instead of just covering it up. I'll give that a try.

[mfindigital]

Originally Posted by Thunderguts

The more I read about the bombs, the more it sounds like they don't do anything to kill mildew. They just mask the smell which is absolutely what I don't want. I ran two 1-ounce cans of Frigi-Fresh through the fresh air intake which didn't eliminate the smell either. I don't think enough is making it past the blower though. I may make a small pin hole downstream of the blower and use a straw to direct it into the system.

Oh! It looks like Nextzett makes an odor bomb that actually kills mildew instead of just covering it up. I'll give that a try.

I have this issue too, one of a million little things I'm sure many of us 1 series owners choose to ignore. Do you have a link to the Nextzett bomb? I found this on Amazon:
https://www.amazon.com/nextzett-9111.../dp/B0092PXMAY

[gjm120]

My car had a little funk smell when I first got it. I used the Meguiar's bomb which helped some. However, I don't think it would have eliminated a really strong smell.

[Thunderguts]

Originally Posted by mfindigital

I have this issue too, one of a million little things I'm sure many of us 1 series owners choose to ignore. Do you have a link to the Nextzett bomb? I found this on Amazon:
https://www.amazon.com/nextzett-9111.../dp/B0092PXMAY

Yep, that's the one. The one from Amazon must ship by boat from Germany because it takes 1-3 months. I ordered the 2-pack which ships from the USA.

[gary_william]

Originally Posted by Thunderguts

Yep, that's the one. The one from Amazon must ship by boat from Germany because it takes 1-3 months. I ordered the 2-pack which ships from the USA.

https://m.youtube.com/watch?v=_QWbFimZ_Gs

May solve your issues

[Thunderguts]

I've noticed some interesting things while working on the HVAC. Depending on the temperature I set on the thermostat, the HVAC will automatically decide on its own whether or not I want the system on recirculate even when I have all automatic settings turned off. Evidently if the computer decides that the temperature disparity is too great it will alter my recirculate settings. I just love having a computer make decisions for me and override my settings, but that's what it does. Who knows what this HVAC is doing. Maybe I can code it out to only do what I tell it to do.

So now I know that it's opening some flap somewhere which releases all the stale mildew-stench-filled air about a minute after I turn off the A/C to dry it out. I just wish it would trust me to decide for myself how to best dry out the system before shutting down.

[dtla1]

Originally Posted by Thunderguts

I've noticed some interesting things while working on the HVAC. Depending on the temperature I set on the thermostat, the HVAC will automatically decide on its own whether or not I want the system on recirculate even when I have all automatic settings turned off. Evidently if the computer decides that the temperature disparity is too great it will alter my recirculate settings. ...

There's a sensor that tests the ambient air quality, I assume this is what is triggering the recirc to turn on.

[JHZR2]

Did you ever figure out or find anything else?

I was investigating the smell in mine today, wasn’t able to get anything up the drain, so I thought maybe to try from the top down... I was trying to watch the flap and noted it has a mind of its own regardless of the recirc settings.

[Thunderguts]

I used my AC for the first time in 5-6 months today and I was greeted with the same stench as always. I don't know how the mildew survives in there without me using the AC for that long. I've tried disinfecting it twice and nothing works. I have to turn my AC off 5 minutes before I get home to let it dry out, otherwise it gets even worse.

It's the same pattern too. I turn the AC off and it blows warm for about a minute. All of a sudden it blows cool again and the stench becomes unbearable. Even though I never use the recirculate feature, the flap must be opening a minute after I turn off the air and letting the stench out.

[Thunderguts]

I just ordered my third can of Klima-Clean and a 60" flexible pipe cleaner. I'm going to round off some .095" weed whacker line and run that up the drain also. I may also use my air compressor set to about 20 psi to blow the crap out of the drain hose. Once I'm sure the drain is open and clean, I'm going to spray half a can of Klima-Clean up the drain hose. I think whatever is causing the stink is down lower than the Klima-Clean can reach from the top. My plan is to flood it from the bottom. I may also spray some diluted Lysol from the top to flush everything out.

I'm really going to town this time. I'm sick of that smell. I've never had a car that smelled so bad with mildew. I don't know what it is about the design that breeds mildew. Maybe it would actually stink less if I used the recirculate feature since the air would have less moisture. First I need to get it clean. Then maybe I'll try using recirculate more.

[Tommm]

I had that with a 944. Filled a spray bottle with H2O and a little bleach. Sprayed it through the intake, put a towel over the dash vent, and turned the fan on high.