Smell from Air Conditioning System

[edbulmer]

We are getting a bad smell from one of our air conditioners. I think it's coming from the pan under the coils that water sits on. It has a drain but some water still sits in there and I think it gets moldy. It is very hard to get to. Does anyone have an idea on how to solve this problem?

[Hudson Force]

I have flushed the condensation pan under my AC. Even though it doesn't drain 100% you can flood it with fresh water and exchange most of it's contents. I have also added some bleach to kill any microbial growth along with flushing. There is also some coil cleaners marketed that can be sprayed into the heat exchanger fins that may be a source of some odor.

[a64pilot]

many ways to fix that, google dirty sock syndrome. I'd post some links for you but I'm on an IPAD and don't really know how to use this thing very well. It's a very common thing, once you "cure" it you need to ensure you prevent it as well. Remember "legionaries disease"? Guess what it's cause was?

[zeehag]

i occasionally spray mine with vinegar and the mold has gone away.no more cough .no more smell. mold gone.
clorox didnt work, sorry.

[Pelagic]

Zee is right bleach evaporates too quickly to help. Best prevention is to spray a 10% solution of Tea Tree Oil into the return once a month

[delmarrey]

The coils are what gets moldy. They sweat when just turned off and get dirty from the fan blowing thru so it collects dirt, which in turn decomposes. That's what smells.
In high rise buildings, maintenance is required to clean out their vents and cooling systems on a regular basis. People are known to get sick from the bacteria that grows in cooling systems.

Perhaps the best-known case of building-related infection occurred in 1976, when 182 cases of a mysterious pneumonia struck members of the American Legion attending a conference in Philadelphia. It took months of investigation and lab work to uncover the culprit: a never-before-seen bacterial organism, Legionella pneumophila, which -- if left to its own devices -- likes to grow in the warm water in a building's cooling towers. When mists from that water are conducted into a building via the ventilation system, researchers found, mass illness can result. Another building-related disease caused by Legionella is Pontiac fever, marked by fever, chills, headaches, and body aches.

Health Library Articles

[Hudson Force]

I notice a mix of messages above. There is the concern with killing mold and bacteria. In addition, there's the cleaning of the coils and the condensation pan. Bacteria (like "Legionaires") and viruses can easily and quickly be destroyed with bleach. Bleach does have a dimenishing shelf life and will evaporate; however, it can be very effective killing microbes within a solution like the condensation pan. It is also true that the bleach is far less effective on porous sufaces and with the killing of molds. The vinegar (acetic acid) the Zeehag recommends will be far more effective with penetrating into areas with mold, but not killing all bacteria. ....dry or in solution? ..... mold or bacteria? .......porous or smooth surface? ..... concentration of the disinfectant? Since you can't fit your AC in an autoclave, the only complete sterilization will be by fire! So, unless you plan to burn your boat, all the plans above will have a weakness, but most of them will vastly improve the problem.

[zeehag]

MOLD causes legionnaires. i know as i had to treat it in hospitals i worked icu. MOLD. it will kill those breathing it in high enough doses.
vinegar sprayed thru the coils will make that mold DIE. one must also remove the cover to the unit and clean out the oooky thick moldwater sitting in the bottom of the unit. in mine , here in tropics, that accumulation took about 3 months.
now i use a spray bottle of vinegar when i use my air conditioner unit. spray thru the filter and coils. you willl smell clean vinegar for only a few moments.

bleach does NOT kill mold. bleach only bleaches mold. it still lives....vinegar changes the pH of the environment so the mold and spores cannot live there any more. i have stated this for years. it is fact.

[GordMay]

Originally Posted by zeehag

... bleach does NOT kill mold. bleach only bleaches mold. it still lives..

It is, in fact, NOT fact.

Bleach (sodium hypochlorite) can kill virtually every species of indoor mold that it comes into contact with, along with its spores, leaving a surface sanitized and resistant to future mold growth.
Bleach cannot penetrate into porous materials, and so is only effective if the mold is growing on non-porous materials.
HOWEVER, bleach is NOT recommended (by USEPA nor OSHA) for mold remediation.

[Hudson Force]

Originally Posted by zeehag

MOLD causes legionnaires. i know as i had to treat it in hospitals i worked icu................

I appreciate your enthusiasm, but your work must not have been in the field of disease etiology. Anyone with a question about the legionella bacterium role as the causitive agent of Legionaires Disease should "look it up".

Don't assume that I disagree with Zeehag regarding the effects of vinegar on mold; however, the change in pH is not a unique characteristic of acetic acid nor is a change in pH an effective method of sterilization. Bleach will also change pH (in the other direction) with the same effect. As said earlier, the venegar (acetic acid) is more effective in reaching microbes imbedded in a porous surface.

In the interest of truth, especially with your safety in preventing disease, there are better sources than advice on boating forums.

[delmarrey]

And, I hope we're talking about white vinegar here.

[zeehag]

funny how the antifungal iv worked when the antibiotics did not. was a lot of challenge keeping some of them alive.

[a64pilot]

Whatever it's worth chlorine will kill almost any living organism, but vinegar will keep many things from growing, it's one reason why vinegar is a very good ear rinse after swimming, what happens is the vinegar wacks out the PH so much that most things can't thrive in that PH, so while it may not kill, vinegar is a very good antibacterial.

I cave dive and we wear dry suits, which means catheters, bad urinary tract infections can occur if you don't keep the catheter hose clean, vinegar is one of the best ways to do that, you don't want a UTI

So I believe chlorine (bleach) may well kill almost anything, vinegar may be an excellent way to keep it from coming back, and I'm not so sure how often I would want chlorine on my evaporator coils, they are usually aluminum, and chlorine corrodes aluminum, of course vinegar is usually a weak form of acetic acid, but I bet it's kinder than chlorine on aluminum?

[Astrid]

Chlorine dioxide is a useful alternative to chlorine, which will pretty much ruin the coils in about seven years. It is EPA approved and found to be very effective against the legionaires disease bacteria (some 50 odd strains).

[Pelagic]

Originally Posted by CaptForce

I notice a mix of messages above. There is the concern with killing mold and bacteria. In addition, there's the cleaning of the coils and the condensation pan.

You are exactly correct…there are 2 separate problems with 2 different solutions
1… Cleaning existing mold, viruses and bacteria from enclosed AC ducts and units
2… Preventing re-growth thru a maintenance program.

1…For cleaning, it requires physical removal of buildup by opening up access and using a steam snake
2…Once clean, or if it is a new system. Tea Tree Oil treatment proved to be a very effective inhibitor.

I got quite involved with this in 2000 helping an Australian Company get their message and product out to the SY Industry.

First as a potential customer, they educated me on “Sick Building Syndrome” and then I trialed their products after cleaning out a 7 year ducted and fan coil system (in crew cabins) that had been only regularily treated with bleach.

Results were very impressive and especially with the full time Crew, all the chronic health problems of living in and out of A/Con in the tropics, disappeared.

I have no affiliation with this company other than I know their product works.
Gelair