I have been getting a lot of customers coming in recently complaining about their vehicles air conditioning systems. Not that they aren't working properly, but that they stink, smell, stench and reek. Kind of like that certain smell your car get gets after making a pancake out of a skunk. This never used to be a problem, well, not a big one anyway, but in the last few years it has become much more common.
The Problem...
The smell is being cause by fungus, bacteria and other microbes growing in the evaporator case of the air conditioner. The moist environment in the evaporator is conducive to the growth of these little stinkers. This is not anything new, it's been happening ever since Fred Flintstone put air conditioning in his Rockecdes Benz. But the Automakers efforts to reduce weight, thus saving fuel, have made the problem worse. They have made evaporator cores smaller and added more fins to keep them efficient but in doing so they made it harder for them to dry out between uses. Thus more moisture, more growth and more smell.
Want to see what it looks like? Put a moist piece of bread in a jar and put it under the kitchen sink. Take it out two days later and you will see what's growing in you're A/C.
The Automakers are very aware of this problem and are making efforts to do something about it.
Some Killer Chemical Solutions...
There are any numbers of products that will get rid of the smell, some for the short term and others for the long term. One of the short-term solutions is using Lysol. Lysol is a disinfectant spray that will kill most of what grows inside the evaporator case. All you need to do to apply it is to put the HVAC into the Recirculation mode, turn the A/C off, put the blower on MEDIUM speed and spray up under the dash behind the glove box area. The fan will carry the Lysol through the evaporator and the ductwork. First spray just a bit on an unseen portion of the dash to see if it will discolor it first. If it does then you won't be able to use it.
Another is called "Frigi-Fresh" made by BG Products and is available at most new car dealer parts departments. It is applied the same way as the Lysol. Both "Frigi-Fresh" and Lysol will need to be used once a week or so.
General Motors offers a product that may control or eliminate odors in the interior and luggage compartment areas of GM vehicles. GM Vehicle Care Odor Eliminator is a non-toxic, biodegradable odor remover. This odorless product has been shown to greatly reduce or remove objectionable smells of mold and mildew resulting from vehicle water leaks (as well as customer created odors, i.e. smoke). You may use GM Vehicle Care Odor Eliminator on fabrics, vinyl, leather, carpet and sound deadening materials. It may also be induced into HVAC modules and instrument panel ducts (for the control of non-bacterial related odors).
Some Coating Chemical Solutions...
There are some products that will apply a coating to the evaporator fins and coils. They incorporate an anti-bacterial in the coating that will keep growth from occurring. Two of the more effective such products are "Clean 'N Coat" and "Cooling Coil Coating". Both are a two-part product. "Cooling Coil Coating" requires special equipment to apply while "Clean 'N Coat" can be sprayed on the evaporator. Both generally lasts about three years.
Chrysler has a coating system their technicians can apply to the evaporator fins and coils.
Some Mechanical Solutions...
Ford has a device called a Purge Module. Basically what it does is to cycle the blower motor on and off to dry out the evaporator and case so there is no moisture to accelerate the growth of mold and mildew. It is part number F8ZX-19980-AA and is available at any Ford, Lincoln or Mercury dealer. It does require an adapter harness depending on the vehicle it is going in.
General Motors has a similar system. It is called Electronic Evaporator Dryer (EED). Where the Ford system runs the blower motor continusly, the GM version runs the blower motor in ten second bursts. It includes a temperature sensor that shuts the system off when ambient temperature drops below what is conducive for the growth of odor causing bacterias. GM says It's EDD device saves battery and is much more effective in that it pushes out two to three times more moisture. The EED can be used on any GM vehicle without modification or need of adapters.
One More Method...
There is one solution that will work to a certain degree that doesn't cost anything at all. That is to shut the A/C off and leave the blower on high a mile or two before arriving at your destination. This will help dry out the evaporator and keep the little fuzzies from growing in the dark.
