Hello, there. I have a 2009 Mazda cx-9, and I was running AC quite a bit in the last year and I noticed it has strong odour from the ac vent, when the AC is on, there is no smell, when I turn off the AC and switch to fan only, for the first few minutes, the smell is very strong, but again, when I turn on AC, there is no smell again. I tried turning off air intake from outside, still the same. I heard Kilma cleaning agent can spray the coils and make it clean, but not able to access the main air vent from the center console. I took it to the shop, two different dealships, all they did was 'smoke' it with some kind of smoke/chemical, which circulate the car, but doesn't help. Please kindly advise. Thank you

Ultrasonic Air Con/ Vehicle cleaning system

see http://www.ageltd.ie/index.php?route=pro...

The Ultrasonic Air Con / Vehicle cleaner is uses in conjunction with the AC System on the vehicle. The recirculation selection is used and using ultrasonic technology, the A/C Cleaning solution is atomized into a fine mist that circulates through the vehicles hearing, ventilation and AC System and fills the vehicles interior. The ultrasonic mist created is designed to eliminate the unpleasant odours associated with mould, mildew, fungi and bacteria. The mist will also eliminate most common odours in the carpeting, upholstery and air bourn odours like tobacco, food and beverages. Designed to eliminate stale vehicle odours, this is an ideal tool to freshen up the interior of any vehicle to provide a fresh and clean smell.

Spraying disinfectant into the air vents won't kill these growths. The chances of anything making it into the system and still being effective are somewhere between slim and none.
Why Air Conditioning systems can smell and be harmful to your health Servicing an Automotive Air Conditioning system is recommended to be carried out every 2 years. But since the Air Conditioning system is sealed, this service will do nothing to remove Mould fungi or Bacteria from the system, and this is what causes "Sick Car Syndrome".

For the past 4 years research conducted by the Georgia State University's Environmental dept has been studying this problem, which in America, afflicts some 4 million vehicles, in every class from economy to luxury. The reason for this is, offending organisms, similar to Mould and Fungus that can grow in your shower or bathroom. But since cars are out on the road many more contaminants are introduced.
Moisture condensation in the Air Conditioning system provide an environment perfect for mould, fungus, bacteria and other micro-organisms to grow. Odours associated with micro-organisms permeate the air duct system, sending these odours into the vehicles interior.

Bacteria Spores

Studies have also shown that bioaerosols incl mould is a common indoor pollutant and exposure to bioaerosols is associated with a wide range of health effects. Respiratory symptoms and lung function impairment are the most widely studied and probably among the most important. Moulds are a type of fungi. There are more than 1,000,000 species of mould and 200 different tyres which people are routinely exposed. Exposure to substantial amounts of mould and mould spores may contribute to skin, eye and respiratory irritation. Industry experts cite new vehicles (less than 4 years old) design as the cause. To increase AC System efficiency, they've made systems with more surface area, and the more surface area you have , the more room you have for moisture and for this junk to grow on. No fungi are known to cause infectious diseases but if you are allergic to these fungi you can have an allergy attack, or if you are mould sensitivity or asthma, they can bring on an asthma attack. Other common systems are headache or nosier.

Bacteria and Mould build up the Evaporator

Adding to the problem could also be blocked water run off. This run off is to allow moisture escape from the Evaporator, a blocked drain will lead to the evaporator not drying out creating an even better breading ground for bacteria and fungi to thrive. Once bacteria of mould take hold it will spread to all the duck systems and can also spread to the interior of the vehicles carpets ect. Some simple advice you can offer your customers to reduce mould build up is

The Air Conditioning should be run on the outside air setting as opposed to the recirculation setting as often as possible. This allows the system to pull in new air and get rid of old moisture.
The Max setting is going to give you recirculated air and should only be used on extremely hot days - and only for short intervals
Never the leave the AC set on MAX while the engine is off. This keeps the vents closed and doesn't allow outside air to get in. The heat created by a closed system combined with the moisture produces a virtual greenhouse for bacteria and fungi
When you use the AC, there should be water draining from under the car. No water means that the evaporator run off is blocked, causing the evaporator to remain wet.