I have excellent news to share. After 2 years of suffering and trying to resolve an intermittent horrible smell plus other odor issues in my third-hand 2005 MINI Cooper S, I finally understand the problem, found a solution, and can share my success story. I am not a mechanic and there probably other solutions to this problem, but this is what worked for me fairly easily and without much time or expense.


Background.


The first owner of this car must have repeatedly used the air conditioner during humid weather, the condensed water vapor accumulated within the air conditioning system, and over time mold/bacteria/fungi began growing. This led to a bad stench noticeable only when the following scenario occurred – driving the car with the air conditioner running, turning the car off, letting the car sit at least half a day, starting the car, and running the HVAC (heat/vent/AC) system without air conditioning allowing the fan to draw outside air inside. For all other scenarios the bad stench was hardly noticeable. If your MINI Cooper has a bad stench that occurs under other scenarios then there are probably other reasons and other solutions that I will mention in a following post to this thread. In my case this odor was so bad that I had buyer's remorse, more than once considered trading my MINI Cooper S for another car, and was reluctant to let friends and family ride with me. The best way to describe the smell is a combination of the smells from cat urine, cow manure, dirty socks, and vomit rolled into one. Seriously.


Solution.


Spray foaming cleaner into the area where the air conditioning evaporator coil is located to kill the mold/fungi growing in there. There are two holes into the “box” where the air conditioning evaporator coil is located that can be used. One hole is on the passenger side and has an opaque corrugated tube leading to the glove box valve to allow cold air to blow into the glove box. The other hole is on the driver side and has a plug covering the hole. We can see these things with a flashlight and our head down in the areas where our feet go while sitting in the front seats. This design must be to allow production of the MINI Coopers for use in all regions. Anyway the tube leading to the glove box is easily removed by gently twisting and pulling away. The plug on the other side is also easily removed without much effort. Place a shallow basin or tray under the car where the air conditioning drip hose is located, which is close to where the exhaust pipe comes down from the engine at an angle and becomes parallel to the underside of the car and quickly meets the catalytic converter. With the engine off and the HVAC system off, spray generous amounts of foaming cleaner into the hole on one side and then into the hole on the other side, alternating until the can of foaming cleaner is emptied. While spraying remember to stop and shake the can, and try to change the position and angle of the can to hopefully get the foam cleaner to go all over the place inside the box where the air conditioning evaporator coil is located. After the can of foaming cleaner is emptied replace the tube leading to the glove box onto the box on one side and replace the plug onto the box on the other side. After a short amount of time the foaming cleaner will become liquid, drain out of the tray under the evaporator coil, down the drip hose, and into our basin/tray on the ground underneath the car. Remember to get that out from underneath the car and dump it. The next time the car is driven use the air conditioner allowing the fan to draw outside air inside (i.e. don't use recirculate) on a medium to high fan setting so humid air will condense on the evaporator coil, become water, go into the drip tray, go down the drip hose – and “wash” away traces of the foaming cleaner.

 

Tips.


The foaming cleaner I chose to use was from a company called “AC-Safe,” the product is called “Air Conditioner Coil Foaming Cleaner,” and model number is AC-920. I bought it at Home Depot and the price was about $5.50 for the can. The Internet number is 100599017 and the store SKU number is 380194. This product is designed for cleaning crap from a home air conditioning evaporator coil. The reviews seem to be very positive, and a couple of the reviewers mention using this product with vehicle air conditioning systems. I attached a plastic straw from a can of brake cleaner onto the nozzle of the can of the foaming cleaner to make sure that the cleaner went inside the box where the air conditioning evaporator coil is located rather than make a big mess around the outside of the two holes leading into that box. I don't know what the inside area looks like where the trip tray and drip hose are found and since my driveway is sloped I actually used a second can the next day, where my MINI Cooper S was parked in the driveway slightly uphill facing the garage on the first day and parked in the driveway backward slightly downhill facing away from garage on the second day. While shaking and spraying I angled the can/straw in different directions and moved the can/straw in and out of the hole to hopefully hit more areas in there with the foaming cleaner. The foaming cleaner has a lemon scent that is not too bad and it pretty much went away after a few days.

http://www.homedepot.com/p/AC-Safe-A...-920/100599017


Other products.


Another product that should work very well is from a company called “Einszett,” the product is called “Klima Cleaner Professional,” and the model number is 961105. It is available at places that sell vehicle detailing products including Amazon.com. It is designed specifically for vehicle air conditioning systems and the price seems to range between $12 and $25. It also seems to have very good reviews. It gets mention periodically in various Internet automotive forums. There is a decently-sized straw built into the nozzle of the can. Note that the can is rather small, about one-third the volume of the can of the product I found at Home Depot. Although I have not used this product there is a good chance that although the can is much smaller, the foaming action might be better and the smell might be more pleasing.



Lysol makes great products for killing mold, mildew, germs, etc. and they have a foaming version of their cleaner available. I first found it at their website by viewing products for cleaning things such as trash cans. I then found it at WalMart and the price was about $2.50. Amazon.com also has it but I could only find it there as a box of two dozen cans. The can is about as large as the other product I found at Home Depot. The nozzle does not allow for a plastic straw from a can of brake cleaner to be attached, but I did notice that after popping the cap off the can there was a “nipple” that we might be able to fit a plastic straw onto. It looked larger than I expected so if we can find a plastic straw slightly larger than the plastic straws from cans of brake cleaner this might work well too.

http://www.lysol.com/products/bathro...hroom-cleaner/

http://www.walmart.com/ip/Lysol-0256...Of-12/11027234



Neighborhood stores that sell motor oil and other vehicle things should also have products for cleaning vehicle air conditioning systems that should probably work fine also.

 

More tips and other possible solutions.


I don't recommend spraying a foaming cleaner into the various vent openings around the inside of the MINI Cooper because behind the dashboard the duct-work for the vents probably don't make airtight/watertight connections, and after a foaming cleaner quickly turns to liquid it may start dripping from all sorts of interesting places inside the car and possibly spraying out of the air vents the next time the car is started and the HVAC fan turned on.


If a MINI Cooper has a bad stench that occurs under other scenarios then there are probably other reasons and other solutions. Most of these are found in various threads here at this forum.


First, it is not uncommon for rather consistent bad smells in the MINI Cooper to be from an old clogged cabin air filter that is overdue for a replacement. This filter is located behind a cover that snaps on and off found under the glove box. There are two versions available; one is a plain filter and the other impregnated with charcoal for absorbing odors. Although the version with charcoal costs a little more than the plain version, it is probably worth the difference. If we are replacing this filter for the first time – or bought our MINI Cooper used and are possibly replacing this filter for the first time - then be prepared for a small mess and a big ugly surprise when replacing it. Spread newspaper under the filter box and get a vacuum ready. When the old filter is removed there is a chance that it will have so much dirt that we won't be able to see the pleats on the old filter and chunks of filth will fall out with the old filter. If this is the case then a new air filter should help a lot with the bad smells plus greatly improve air flow through the HVAC system, almost like when it was a brand new vehicle. There are a number of posts here where people have found this to be the case. One person even wrote that they found dead mice along with the thick dirt on the pleats of the old filter!


Second, it is also possible that the air conditioning drip hose has some sort of clog inside, or is not straight, allowing water to drain through. The drip hose is a black flattened oval stiff rubber-like hose under the car, found close to where the exhaust pipe comes down from the engine at an angle and becomes parallel to the underside of the car and quickly meets the catalytic converter. To get a good view of it we need to drive onto a pair of ramps or raise the wheel on the front passenger side of the car and use a jack stand. It is easier to see on the passenger side of the car than the driver side. Don't be too aggressive when fooling around with the drip hose otherwise we may end up poking a hole in it or dislocating it from the drip tray.


Third, some people suggest spraying Lysol or Febreze into the place on the car where outside air is drawn in. This would work best with the HVAC air filter temporarily removed. For the MINI Cooper the outside air seems to be drawn in through the grill at the base of the windshield on the passenger side. I tried doing this and found it easier to do with the hood raised and spraying into the box-like area under the grill on the hood. Afterward the inside of the car did smell like the product I was spraying, but it did not cure the intermittent horrible smell problem I was trying to remove. I would guess that we would have better success with this approach if we temporarily removed the HVAC filter, kept the snap-on cover off, put the can into the HVAC filter area, and pointed the can up and toward the center of the car. I write this because with the electrical system powered off we can reach in there and actually touch the blower fan.


Fourth, if there are other smells inside the MINI Cooper that we want to remove, a company called “Dakota Products” has something called “Odor Bomb” for about $12 per can. It is available in several scents and Amazon.com is one of the places that sell it. The reviews are mixed. The second owner of my MINI Cooper S tried to cover up the occasional bad stench by spraying or dripping cologne or something around the inside of the car. His approach did not work. So I really had two odor issues to overcome. Odor Bomb and a good cleaning of the inside of my MINI Cooper really did remove the cologne smells – but not the smells from the mold/bacteria/fungi growing on the air conditioner evaporator coil or on the drip tray below it. Although I chose the neutral fragrance of Odor Bomb, the cleaner left a new smell inside the car that took a long time to go away. I found the smell of Odor Bomb neutral made the inside of my MINI Cooper S smell similar to a hotel room that had just been cleaned thoroughly. Not an offensive smell, but a rather strong smell. I'd estimate for the first 3 months the smell of the cleaner was strong and after that for the following 6 months it was much weaker and less noticeable. After 9 months the smell of the cleaner was nearly gone. I would imagine Odor Bomb would be best for removing smells from a previously owned car that had been smoked in. When using this product make sure to spread newspapers on the floor where the front passenger puts their feet, and old towels on top of the newspaper, and then put the can of Odor Bomb on top of that. The product sprays out the top of the can, and some of it sort of spits out and more or less falls straight down. I can't remember the specifics from when I used Odor Bomb but I remember I temporarily removed the HVAC filter, turned on the electrical system, started the HVAC fan on a high setting, enabled recirculation, triggered the can to start releasing the product, waiting maybe 20 minutes for the can to empty itself, and then leaving things alone for another 1 or 2 hours. After that I cleaned up the small mess from the spraying/spiting product, replaced the HVAC air filter, and aggressively let the car air out whenever possible – parking in dry weather with the windows open an inch or two, driving with the HVAC fan usually on a high setting, avoiding the use of the recirculation function, and so on.



Fifth, for whatever it is worth, I also tried letting a non-MINI mechanic solve this problem by using one of those products similar to Einszett Klima Cleaner Professional probably applied by spraying it up the air conditioning drip hose. $50 later for less than 1 week my MINI Cooper S smelled fresh inside but it did nothing to remove the occasional bad stench from mold/bacteria/fungi growing on the air conditioner evaporator coil or on the drip tray below it.

 

Last resort.


I'd imagine a MINI Cooper dealership can effectively remove odor problems. From what I've read in the Bentley's manual, it seems the air conditioning refrigerant would be evacuated and the whole dashboard removed in order to access the area where the evaporator coil is located. Multiplying the hourly labor rate at the dealership by the several hours needed for this job could easily result in a bill of several hundreds of dollars. But it would probably be effective and definitely cheaper than trading/buying a new MINI Cooper!