A cure for the dreaded 'Dirty Sock Syndrome'?

September 19, 2000
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During the energy crisis of the early 1970s, heat pump systems became popular for many commercial and residential hvac applications because of their lower first cost and potentially energy-saving performance.

Manufacturers, wholesalers, contractors, and even electrical utilities rigorously promoted the concept, and a new market was launched.

Shortly thereafter, however, came the complaints, particularly in the Southeast, of an odor originating from the much-endorsed units. This foul smell sent manufacturers, wholesalers, and service entities scrambling. The odor was characterized in many ways, but the most vivid description was “like someone’s gym socks found their way into my a/c unit.”

The term “Dirty Sock Syndrome” was born, to the chagrin of the industry, and soon became the unofficial name for this heat pump phenomenon.

The only known remedies at the time were to clean or replace the coil, use drain pan treatments, or in extreme cases, replace the entire unit — and even that didn’t always solve the problem. Generally speaking, however, frequent cleanings with bleach did temporarily reduce the odor to acceptable levels.

In the late 1980s and early 90s, indoor air quality became a nationally recognized issue; thus, the reports of the Dirty Sock Syndrome accelerated.

Newer and more energy-efficient units seemed predisposed to the problem. It also began occurring during the heating season as well as the cooling season, but especially during “shoulder” seasons like fall and spring, when the units would be used for heating at night and cooling during the day.

The condition became so widely recognized that it was no longer limited to just heat pumps or the Southeast.

Generally, the early cleaners like chlorine have been banned for use in a/c systems. As a result, service contractors are using EPA-registered biocidal agents on coils, drain pans, air filters, and insulation to suppress the problem.

Like the earlier remedies, though, these agents do not provide a permanent solution. The problems eventually return in just a few months or less.

What causes the odor?

In order to find a permanent solution to the Dirty Sock Syndrome, it was first necessary to understand how the odor was generated. Curiously, the cause of the problem all along was the simple growth of mold and bacteria on the coil, as indicated by the effect of early cleaners.

Heat pumps were particularly susceptible because, unlike conventional heat exchangers, their heating cycles were not hot enough to kill the microbes that thrived on their wet coils during the cooling season. Instead, the temperature was just warm enough to slowly “cook off” their organic odors, producing that gym sock odor.

Adding to the problem were the water and organic debris in the drain pan, which formed a fertile garden of microorganisms. The slow warming of this contaminated water released a plethora of spores and toxins into the air that served the conditioned space.

Why the problem appeared during the heating season was linked to the “reverse mode” operation for defrosting the outdoor coil. This process generated moisture on the indoor coil, giving dormant microorganisms and residual organic matter new life, and providing a simple but effective odor release and carrier mechanism.

In today’s high-efficiency units, the old problem is exacerbated. Larger coils and more closely spaced fins create an expanded surface area to retain even more organic material.

In addition, they retain more moisture, stay wet longer, and their drain pans hold more water and organic debris. All of these factors contribute to a longer and more productive cycle of microbial activity.

This greater activity equates to more spores, toxins, and odors for a longer period of time.

Mold: A survivor

Why is mold so difficult to control?

Mold is at the bottom of the food chain. It thrives on very little, grows rapidly, and produces spores, volatile organic compounds, and other toxins. One organism can multiply to trillions in less than three weeks.

And mold occurs everywhere — in hvac systems in homes, schools, workplaces, entertainment centers, vehicles, etc. They all are mold reservoirs.

As noted above, a/c equipment interiors provide an ideal environment for mold growth — it’s dark, damp, and filled with nutrients. The result can be like blowing air over a swamp or through a sewer and then into our homes, vehicles, and workplaces.

According to the World Health Organization (WHO), 60% of IAQ problems and allergies may be mold-related. Some IAQ diagnosticians and practitioners today say the figure may be as high as 80%. The increased usage of air conditioning systems (installed base) almost directly parallels the increase of allergies and IAQ problems.

As mold and bacteria grow on coils and in drain pans, they are disseminated through the ducts to occupied spaces. Some mold products (toxins) produce serious and sometimes life-threatening reactions, including allergy, asthma, hypersensitivity pneumonitis, and even bleeding lung disease.

Additionally, mold creates a troublesome maintenance problem. Its activity results in dirty coils, an increase in pressure drop, loss of heat exchange efficiency, dirty and sometimes plugged drain pans, and excessive energy use.

Using UVC

Accurate Environmental Systems has found that the most successful way to handle system mold is through continuous source control using hvac-style UV germicidal lights.

Ultraviolet light in the “C” band (UVC) has been used for more than 65 years to kill microorganisms in hospitals, laboratories, food processing, and pharmaceutical plants, and even at the nation’s Center for Disease Control.

However, conventional UVC products are limited to still air applications where ambient temperatures are of 80° to 90°F, and are therefore not effective in the cold and moving temperatures found where mold grows in hvac systems.

As a result, our company has standardized our use of a new generation of patented UVC lights that are specially suited for installation at the coil and drain pan area, to eliminate mold and bacteria right at the source.

Steril-Aire, Inc.’s UVC Emitter™ has been independently tested and proven to produce up to seven times the output of conventional UVC devices in the cold, moving air environments of hvac systems, eradicating mold and bacteria quickly and effectively.

The UVC energy attacks the organism’s DNA and either kills it immediately or prevents it from reproducing. Continuing exposure degrades the carcasses and any other organic material through vaporization (without heat), cleaning the coil to “as-new” specifications.

Emitter tubes typically last more than 7,500 hrs (“on” time), or slightly over one year. The lights pose no danger to equipment, individuals, or furnishings, and there is no risk of secondary contaminants such as particles, ozone, or chemicals being released into the system or space.

For our first UVC customers, the original motivation for installing the lights was to abate IAQ complaints and/or allergies. What we didn’t anticipate when we started working with UVC lights was the elimination of Dirty Sock Syndrome and the return of system efficiency.

In place of the unwanted smell, customers have repeatedly told us that the lights produce a clean, fresh air sensation in their buildings and homes.

Another unexpected benefit has been the complete removal of all the organic material typically found in the interior of the coil and plenum area and in the drain pan. The UVC devices thus eliminate coil and duct cleaning, as well as the use of drain pan tablets and biocidal agents.

We have found that the pressure drop across the coil returns to the original design specifications or, stated another way, heat exchange efficiency and system capacity return to “as new.”

All this and IAQ

The new UVC technology also does what it was originally designed to do: enhance IAQ and reduce the incidence of allergy and illness.

To cite an example, a residential customer named Laura Toms was acutely ill with what had been diagnosed variously as Chronic Fatigue Syndrome, allergies/environmental illness, and Multiple Chemical Sensitivity. After allergy testing revealed a strong sensitivity to mold, we recommended use of UVC Emitters in her Columbus, Ohio home.

About six weeks later, she wrote, “Since you installed the UVC system, I believe I have recovered to the point of being 90% cured, and improving all the time. If you ever had to live with the debilitating fatigue, temperature fluctuations, sore throats, and other symptoms I’ve endured, you’d realize how thankful I am to feel normal again.”

An average installation of UVC Emitters will kill up to 90% of the “fly-by” bacteria and viruses passing through the system. This reduces the recirculation of colds and flu virus or any other airborne disease through the hvac system. If used to control infectious diseases such as TB, the UVC system can be designed to eliminate more than 99% of the bacteria for the greatest level of protection possible.

Given their multiple benefits, we have found that UVC devices are one of the most innovative maintenance and control items to hit the hvac market in years.

A properly designed and installed UVC system will provide your customer with healthier, more energy-efficient and productive environments, while removing those dirty socks from their air conditioners.

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drity socks syndrome/uv lights

February 16, 2009
How do I find the ultra violet lights you talk about here, used to prevent dirty socks syndrome?

drity socks

February 19, 2009
looking to finkd the ultra violets you talked about.

where you find UVC lights

November 12, 2009
You can find them at most heating and air conditioning supply houses like Baker Bro.,CC Dickson,Johnstone,etc...

Lights Are a SHAM

December 6, 2009
spent hundreds of dollars on a duel light system, proble still here. unit was installed last july 2008 smell started in the winter, called installer they came out sprayed coils, helped for a few weeks, then BAAM back again. so i purchased the lights. NO HELP AT ALL. only has smell in winter I live in Georgia. It is now dec 2009 and sometimes the smell will be so strong it wakes you up at night. installers are on the way back next week. save your money dont buy lights. Im going to ask for a dipped coil this time out

Why Dipped Coils

December 27, 2009
Why dipped coils. Just had this system installed this past March. I have a Rudd 5 ton 410A system and have had this issue since the start of winter, the installer and dealer had never heard of such an odor. Meanwhile the installer requested that I place a couple of dry air gadgets in the return. I think that this is a cover-up. It seems to occur mostly during the defrost cycle. They will come out this week and change the coil so they say. What is the cure for this smell? If lights are a sham then what next.

Got UV - Light -- Now the Coils are sprayed

December 29, 2009
We just got upgraded to a 13 ton, 15 s Maytag unit. It came installed with the UVA lights to help fight mold and bacteria on the coils. But about a month ago we started smell a musty smell and called our Heating & Air Service. They informed us that the system has "Dirty Sock Syndrome". So they sprayed a coil cleanser into the central duct system. It helped reduce the smell so far. We'll see if it continues to help. We live in the Mid South Region, where the climate tends to be somewhat humid.

Dirty sock syndrome

john H.
January 8, 2010
had it in my goodman 4 ton package unit during defrost cycle. installed a Saber 24 volt 16 inch UVC light ($120 at Totaline). No smell anymore and the air smells fresher.

dirty sock syndrome

January 17, 2010
I have the same problem with brand new air conditioner. No smell with old a/c unit. Live in Fl. Used the heater on the unit. Then went back to A/C and here comes the dirty sock smell. Smell fades when use only fan or heat. Put the A/C on and it stinks up the whole house to the point it is not tolerable. Had to turn it off and leave. Installer says I need to spend another $600 for new ductwork at entry to house. Doesnt make sense that it only smells when a/c is on and no smell with heat or fan only. If I pay the $600 for new duct work and it still smells, then what? The guy act like he had never heard of DDS. Treated us like the cause was our fault. Then I see it all over the internet as a huge problem. To everyone who has this problem with your new a/c, keep complaining and dont let them intimidate you. Its the coil in the unit, not you.

dirty sock smell

February 2, 2010
I've got the same problem. My unit is 1 yr old. Now a remediator wants to install a RGF(hydroxil solution) mechanical device for $800 to kill the algae on the heating coils. Should I does this or try to have manufacturer replace coils with copper coils. I'm desperate!!! Any feedback will be greatly appcreciated.

defective coils in new A/C

February 2, 2010
Gail I have the same problem with new a/c under warranty. Many, many of us are having this problem. Most important thing to remember. If your old unit did not have this smell with much more likelyhood of algae, bacteria, etc. why would a new unit have so much more that it would smell so bad and your old one would not. It cant be us. It has to be something that is in or on that new evaporator coil causing this. Try and get company that you bought unit from to replace coil Continue posting on the internet any where you can. It is a shame to have a new unit that is making us sick. Wish I had more answers. Please keep in touch here if you can. We are stronger in numbers. Anyone that has this problem, please post here and lets try not to let them rip us off any more. This should not happen when you get a new unit installed and it did not happen in old one.

Dirty Sock Syndrome!!

February 5, 2010
I wish I had found this site last week!!! Our system is 6 years old and we have this intermittent smell mostly during heating season and particularly when it is very cold. We have just paid $600 to have the system cleaned (i.e. dust from ducts etc removed - there was very little!!) and sanitized. However when we talked to the technician he said that possibly that would not help with the smell problem as it was probably coming from the coils in the heat exchanger. I had previously noticed that when the smell was prevalent the coils were very cold but had not made the connection to bacteria and mold. So now we are waiting to see what is the outcome of the cleaning but not with high expectations. I feel that without the insight provided in this site I have been duped by this company's salesman as when we described the problem he made no mention of the probelm with the heat exchanger pipes though it is quite evident that it is a well recognized issue in the industry.

Dirty Sock Syndrome

February 6, 2010
Our a/c unit is 6 yrs old(American Standard) never had a problem until we installed new furnace and had duct work cleaned in Oct. Now after heat is on and you turn a/c on you get the terrible odor. (which we thought smelled like dog do!) We had a technician tell us that Am Standard had a problem with coils a few years back,and gave us the name dirty sock syndrome, but now I am seeing a lot of people are having the same problem. It seems to me the manufacture of these coils need to cough up replacements. Why are we all having to spend hundreds of dollars for so called fixes that do not work!!

Dirty Sock Syndrome should be Defective Coil Syndrome

February 6, 2010
Old unit, no smell. New unit, 6 months later, strong smell. I was told I needed duct w/ holes in it replaced for hundreds of $$. Couldnt understand why duct would smell with new unit but not with old one so I waited to give them the money. Good thing, someone else said no holes in duct. Didnt need replacing. Not only are we being sold defective units, they are using it as a money trap to sell other things that we dont need. People are also somewhat embarrassed because their house stinks and they feed off of that. Some of the manufacturers say tests show its bacteria on the coil. Any chemist will tell you if you swab anything, it will show bacteria, unless it has just been sterilized. Strong possiblity of what is causing this smell, is they are using junk recycled aluminum in making the coils causing this distinct smell. They will continue to make the homeowner replace everything then act like its some big mystery because manufacturers dont want to recall all of these defective coils. The metallic fumes happen to smell like stinky feet like sulfer smells like rotten eggs. The bigger problem is, some people are getting sick from the odor infiltrating every inch of their homes and they are breathing these toxic fumes emitting from defective coils. Everyone speak up if you are having this problem and get it to show up in more google searches. A class action lawsuit will force the manufacturers to own up to what is really causing these fumes. They need to recall these things like Toyota finally had to do with their gas pedals.

dirty sock syndrome

February 10, 2010
What about the coils that have been replaced but the smell still comes back what next ?

dirty sock syndrome

mad consumer
February 11, 2010
Could be because the replacement coils are made out of the same junk metal the original one was.

Dirty Sock Syndrome

February 13, 2010
Yes...i'm having the same problem as all you other unfortunate people who are duped and to what extent??? I've heard of people getting sick from the smell or people with allergies that are enhanced by this DSS. My Trane unit is only five years old and had the coils cleaned to no avail. The oder keeps comming back!!! It's time the manufacturers took the blame and replace these coils before someone really gets sick or even worse...i'm will keep hounding the Trane Mfg to replace the coils and spread the word about DSS.

dirty sock

R in N. FL
February 14, 2010
We have a home with 2 Carrier units, built in 2006, and has had the dirty sock smell every since we moved in. The installer told us it was dirty sock, but, didn't seem to have any idea what to do for it and offered no solutions. It happens during heating and cooling and severity varies depending on humidity. It's been very humid here in N. FL this winter, so, having dirty sock odor quite a bit lately. It's unbelievable that this problem is so widely reported on the internet among consumers in the Southeast, as yet, the HVAC mfg.'s don't seem to be acknowledging or addressing it. Perhaps they stay quiet in fear of liability, but, it seems now a big class action law suit may be the only thing to force action. I'm ready to sign on.

Dirty Sock Syndrome

S. Florida
February 14, 2010
The dealer I bought my new A/C unit was supposed to replace the defective coil but is doing everything in their power to stall until the warranty runs out. Not only do they try & sell you all the remedies that do not work, it is also a stall tactic to eat away at the time you have on your warranty. The Better Business Bureau is useless. Especially if the dealer is a paid member. I went to an HVAC professional forum where there is alot of complaints from consumers on Dirty Sock Syndrome but the professionals on there give you the same run around. But it does give you an idea of other consumers that have our problem. I just found a consumer site called Ripoff Report that will show your complaint in a google search & looks like it could possibly be a good place for people with similiar problems to come together for class action suits. Its not just for HVAC problems but all comsumer problems. I have lived in my home for over 15 years & have never smelled anything like this until we replaced our HVAC system. As soon as we went from heat to cool, it started & is getting worse. This smell is unbearable & it is unhealthy for my family. I am at a loss of what to do. I have even considered getting a loan to replace the whole unit or moving until we can get some kind of resolution from the dealer that sold us this thing. A smell that strong coming from a new HVAC system is just to risky for my family to breathe.

Dirty Sock Syndrome

Lou in NC
February 15, 2010
Yes, I have the Syndrome with my new Trane before & after duct cleaning which cost $800 - did not have this problem with my old Trane. I agree the manufacturing companies should be responsible for changing the coils. It should be a recall as on cars and at no cost for customers. I think I'll check into the Ripoff report on google - thanks.

Trane alluminum coils

Daniel in Houston
February 21, 2010
Me and a friend of mine just installed new coils in both of are houses. Mine smells noticeable his reeks .....we're ready to sign.

New unit that smells

Dean in lower Alabama
February 21, 2010
My unit is less than a year old, it was installed around April when the heating season was over, we never noticed a smell until the late fall. It got worse as the winter approached. The company that installed the unit didn't seem to know where the smell was coming from, but after a thorough investigation they came to the conclusion it was the coils. They cleaned them, but the smell returned after a couple of days. I called them back after about a week, left a message and have not heard back. We have been using electric heaters mostly this winter and the eletric bill has doubled.

Heats on... Dusty smell

February 22, 2010
We bought our house new. We've been here 2 1/2 yrs. This winter when the heat kicks on it smells like dust, sneezing. I have a baby that's close too 3 mths old, his nose is runny and he sneezes when we smell it. My husband and I seem more congested, seems like I breath in something because I feel like I've swallowed something... We live in Texas so it's not very cold here. The smell burns my nose! I'm not sure if this is what's going on with everyone else, sounds like it. ;(

Dirty Sock Syndrome

John LeVasseur
February 24, 2010
Installed a new Trane unit to replace 20 year old unit. Never had any problems with old unit. New Trane unit started smelling bad, found out from serviceman that it's called the Dirty Sock Syndrome. They came out just before our warranty expired, and cleaned the coils with bleach. The odor went away for awhile, but occasionally comes back. Now a year later, the problem is getting worse. Serviceman coming back today to look at it.

Dirty Sock Syndrome

February 24, 2010
We have had the same problem since replacing our a/c in 2008. With the old system, no problems, no smells. New system the smell was horrible. We called the installer & they came out & sprayed with a disinfectant and said that it was mold build up from us switching from heat to a/c and that we will need to have the system cleaned annually to avoid the mold problem. The spray lasted a short time then the odor was back. We have had headaches & sinus/cold symptoms since changing out the system and now believe it is due to the a/c. When we called the installer again, he said it was "dirty sock syndrome" and that we can google it that it is a real phenomenon and the only thing you can do is to have your system thoroughly cleaned at the end of the heating season. We live in FL, there are days when it's 80, then days when it is 50, so we don't have a "heating season" per say. Not to mention that the cleaning is only a temporary fix and not a cure. I don't understand how the manufacturers of these units can get away with selling these systems with this problem and not have any responsibility in the resolution.


HVAC Contractor
February 25, 2010
Guys. The best way to get rid of the smell is to talk to the installing dealer about a coated coil. It has worked great for us. However there maybe a few things that each company/brands may require you to do before giving a coated coil(Coated Coil is Very $$). UV Lights seem to work 50% of the time. Cleaning duct work to me is not a true answer and is a waste of money because it is not possible to truly clean 100% of the inside of a duck system, more like what you can reach. If your duct system is a problem your better replacing it but more than likly its not your duct system. HVAC contractors are unsure what causes these problems but from my experience it seems to depend on the enviroment the house is in and around and as the coils get larger to provide better energy comsumption it provides a larger space and fertile garden for microorganisms. But we do see DSS with older units as well, not just new units. The percent of homes that have this smell is less than 1% and I truly believe it is not a Dealer or system problem. Thought this might be helpful for you homeowners.

smell only from one unit

February 25, 2010
we have an office six split not heat pumps all installed at the same time and only one has that musty smell, well i cant smell it but the complaintant does and states that it only comes on after its been heating then call for cool but it does go away, did spray some coil cleaner and the smell went away only for it to get cold out for a couple of weeks, and then warmed up out the other day and bam the smell was back!planning on having the system cleaned duct and all

Another Solution

February 25, 2010
Getting a coil coated is expensive and requires the unit to be down for some time. UV light, while somewhat effective, only travels in straight lines, so the light can't bend between and around coils. Controlled Release Technologies has a DSS kit consisting of two products, First Strike Microcoat and Fast Attack. Fast Attack is EPA registered and not available for residential application. First Strike is a coil cleaner. Their website is www.cleanac.com

Another Solution

February 25, 2010
Getting a coil coated is expensive and requires the unit to be down for some time. UV light, while somewhat effective, only travels in straight lines, so the light can't bend between and around coils. Controlled Release Technologies has a DSS kit consisting of two products, First Strike Microcoat and Fast Attack. Fast Attack is EPA registered and not available for residential application. First Strike is a coil cleaner. Their website is www.cleanac.com

Bad Smell from New HVAC

to HVAC contractors
February 27, 2010
Ya gotta be kiddin me. Clean the coil?When they opened up my almost new A/C unit, the evaporator coil was clean as a whistle but that smell was reeking from the coil. I have a 2 story house with 2 units. Brand new clean one stinks to high heaven. Older one, no smell. How can it be "my enviroment"? Both units are sitting side by side outside my house in the same enviroment. Exactly what is it that I might be "required" to do to get that very $$ coated coil? Im out thousands of $$$$.I have a brand new unit under warranty that is unusable and my dealer wont call me back. Got any tips on that? Talk to a few real estate agents and that less than 1% is not accurate. They are smelling that same Dirty Sock Syndrome in at least a third of brand new homes they have gone in. Nobody ever lived in them. Has nothing to do with the enviroment. Its either units switching from heat to cool or those that go to defrost cycle with heat. Tell your manufacturers to coat the "larger" coils before they sell us something that can ruin our lives. Your reputations are on the line.

dirty sock syndrome

Air conditioning & Heating Inc
March 11, 2010
It is not the air conditioning system, I have used a treetment and have had good luck. Look for " EXODOR " made by WALEX

More info

March 11, 2010
For ones with the problem, I'm interested to know, what make and model # of the air handler. The location and when it was installed. I install Bryant heating and cooling products recently starting in 09 bryant uses a tin coated evaporator coil which is noted by a T in the model number. So far I have not seen any issues with dirty sock syndrome with my customers here in N Fl.

Dirty Sock Syndrome

March 23, 2010
We have a condo in SW Forida. We bought a Trane system in 2008. At first, the noise was like an airplane landing. The dealer exchanged the motor for a smaller motor. This year, after a bout of cold weather and the air conditioner went on, we smelled an odd odor. The dealer said it was dirty sock syndrome. He sprayed some type of disinfectant and said that MIGHT take care of the problem. He said it was probably caused because the coils might be made from recycled aluminum. He never mentioned the word--mold! He told me if that doesn't work, they will have to replace the coil. It is under warranty, but we will have to pay around 300 dollars for labor! Is the white on the coils really mold??

Dirty Sock Syndrome

March 27, 2010
We had a new 3-1/2 Ton American Standard / Trane Heat Pump installed in January 2009. During the first heating and cooling season we did not have a problem with any odor. In November of that same year we did experience a very bad smell coming from the ducts every time the unit was running after the defrost cycle. I contacted the Dealer who installed our unit about the smell and he said that it sounded to him like we had "The Dirty Sock Syndrome". Never hearing about this issue before I did a Google search and read many of the pages of articles that had been posted about this problem online. After reading the posts about this problem there was no question in my mind that this was what was causing our smell! Prior to my internet research our Dealer had agreed to come out and 'clean' our coils which he did. Let me say that our Dealer is 'Outstanding' and the problem was not caused by anything that he had done it was caused by the company that made the unit!(American Standard / Trane / Ingersoll Rand) I shared with our Dealer that I appreciated him coming out to clean our coils but I didn't think that cleaning would solve our problem based on all of the posts that I had read online. Sure enough, a short time after he cleaned the coils the odor returned! I had already sent several email letters and made several phone calls to the National Customer Service Department of American Standard / Trane/ Ingersoll Rand about the problem I was having with our new Heat Pump. The responses I was receiving back from them were not good! Attached is part of the response I received back from them after my first email. "Thank you for visiting our web site. I appreciate you sharing your concerns with us. There is an issue known as "Dirty Sock Syndrome" which occurs in the evaporator coil of some heat pumps during the defrost cycle. Dirt Sock is an environmental issue and not equipment related." Believe me, I was not happy or satisfied with their response! How could the problem be 'environmental' when our old Heat Pump that we had in the same 'environment' for about 25 years never had this problem! After many more phone calls and email letters to them they agreed to replace my coils! This morning (3/27/2010) my new coated coils were installed! I feel sure that this should resolve our problem with the "The Dirty Sock Syndrome" smell. I know and understand the problem the odor causes but more importantly the health concerns and risks that everyone has when dealing with this issue! The "Dirt Sock Syndrome" has been a problem for 'many' years and the companies that manufacture HVAC equipment are aware of the problem and they do have a fix for it. The problem is 'money'! They are not willing to put the more expensive coated coils in the units that they sell to avoid these problems in my opinion because of the increased cost! Again, in my opinion cleaning the ducts or cleaning the coils won't fix this issue! I strongly believe that the problem is caused by the coils and the solution to the problem is to replace the coils with the new coated type! If it was not an equipment issue why would American Standard / Trane / Ingersoll Rand offer this as a solution to correct the problem? I really hope that everyone that is experiencing this problem are able to get it fixed soon! Thanks, datgrt

Dirty Sock Syndrome

SE Florida
March 28, 2010
datgrt, I am so glad you were able to get the coated coil. Did you have to pay anything out of pocket? You are lucky to have a good dealer. Ours will not call back or answer the BBB complaint. We are still stuck with this stinking NEW a/c coil. It looks like we are all going to have to be persistant to get what we paid for. My new a/c is a Nordyne. Pat in SW Fl. I dont think the white stuff on the coil is mold. I think it is the oxidation of the crappy metal our coils are made of. I am sitting here roasting with no a/c because the odor is intolerable. I will keep trying to get a coated coil.

Dirty Sock Syndrome

March 28, 2010
Hello SE Florida, We had no out of pocket expense. The new coated coils were replaced at no charge. I dealt directly with the company that manuafactured our Heat Pump (American Standard / Trane/ Ingersoll Rand) and they replaced the coils and as I shared in my first note our Dealer who is 'Outstanding' installed the replacement coated coil at no charge! Thanks for your note and I hope you will be able to get your Dirty Sock Syndrome problem corrected soon! datgrt

Dirty Sock Syndrome

Aaron C
March 29, 2010
Man, It took me a long time to find this forum.. and I'm glad I did.. We too have had this problem for a few years now.... It's mostly in the Spring. Me and my son have been sick quite a bit lately and I believe it's from this issue... I can't believe they are allowed to have this poison pumped through our homes.. no possible way with this many post that they are not aware.. problem is I'm sure I've waited past warranty...

Dirt Sock Syndrome

Comfort Time Live
April 3, 2010
To all who are concerned about this issue; I am a radio talk show host that would love to hear from anyone of you to discuss your issue and perhaps your resolution, live on the air. My talk show heard twice a week in South Florida, Port St. Lucie, Fort Pierce, Vero Beach area on WPSL 1590AM or live audio and video on the internet at www.comforttimelive.com, is a consumer advocate, non-profit show, dedicated to helping educate consumers and guide them in the right direction. This is a great topic that would provide information, and for those that have found a fix, the opportunity to share with other listeners around the world how they over came it.


April 3, 2010
datdrg We have just come up with the same problem. We are in Sarasota and have spoken to the dealer who said he is going to charge us for the house call. I wish you could give me the name of your dealer. email me: natekppl @comcast.net

Dirty Sock Syndrome

S. Fl.
April 5, 2010
Thanks for the radio interest. I will go to your website now.


Chris R
April 6, 2010
I have worked in the heating and air conditioning service business for over 20 years now and have to date one customer that has brought this problem to my attention. I know that many consumers think all contractors are dishonest but I promise that this is an issue that we have gotten very little support from the engineering and manufacturing sectors. The customer I referred to has had the coil replaced and still has issues. We didn't blow it off but researched the system and tried several fixes at our expense to satisfy the customer. The manufacturers need to be held accountable for either a bad design or not being responsive with a good fix once they were made aware of the problem. There are some fairly new IAQ products that may be the solution but I realize as a consumer people don't want to pay another $1000 to slove a problem that didn't exist with the old system.

Dirty Sock Syndrome

J Crox
April 6, 2010
I had a brand new "High efficiency' Trane electric heat pump installed in June 09. I had an old furnace (70's) and a dated AC unit (93). I was sick of the high gas bills, and there was a tax incentive to get a new energy efficient system. Sounds awesome right? WRONG!!!!!!! In Nov 09, I started to notice a smell coming from the vents. Freaked me out. It seamed worst when it got cold. I had never smelled this with the old system. Finally, I started researching it and found out about DSS. I was embarrassed by the odor, I didn't want to have company over anymore. I felt like a fool for spending thousands on what I thought was a "smart" buy. I had the local company who installed it come out to look at it. They sprayed the coils with some cleaner that was suppose to prevent the smell from coming back. The next night (4am), THE SMELL WOKE ME UP! I talked with the contractor and he said that he is going to replace the coil.... fingers crossed... I will report back!

Dirty Sock Syndrome - Update

April 11, 2010
In response to a note that I had posted on another forum concerning 'DSS' the following message was posted. --------------------------------------- Thanks for your information, we too have been fighting DSS for years now. We have had the 'coil replaced twice' and have had it cleaned two years in a row. After reading your post I know I have to do what we were going to do last year and that is coat the coil. I have spent too much money, UV light, cleanings even as I mentioned above replacing the coil. Our AC guy seems to think that our problem is our whole house dehumidifier, causing the smell, I like to point out to him that the dehumidifier was in place for a few years before we replaced the coil with no problems. So I have researched a couple of companies that do the coating and I am going to cross my fingers, and toes, that this will finally fix the problem. No one should be afraid to use the AC because it may smell when you do. --------------------------------------- Based on what I have read about the 'DSS' replacing the coils with the same type coil won't solve the problem. I really believe that you need to use 'coated' coils! As I shared in the note I posted earlier, we had new coated coils installed on March 27th and I am thankful to say that we have not smelled any odor since that time! I hope this information helps! datgrt

Dirty Sock Syndrome

April 11, 2010
Title: DSS By: nako Posted: April 3, 2010 3:36 PM datdrg We have just come up with the same problem. We are in Sarasota and have spoken to the dealer who said he is going to charge us for the house call. I wish you could give me the name of your dealer. email me: natekppl @comcast.net -------------------------------------- Hello Nako ...... Sorry to hear that you are experiencing the 'DSS' and also sorry for the late response to your note! We live in Coastal North Carolina so I am not sure our Dealer will be any help to you living in Florida! I will send you an email with our Dealer's name. I hope this information will help! datgrt

Dirty Sock Syndrome

Brand new A/C stinks
April 12, 2010
Datgrt, Even though you were able to get your problem fixed, you still come back here to help those who are still stuck with this problem. You are an inspiration. It is people like you that make a difference in this world. You were able to take on the big manufacturer and get them to do what is right even though they did not want to. Many of us are embarrassed by this smell when we first smelled it and didnt have a clue about a syndrome in new a/c units that smells like hundreds of stinking feet. I, too, was embarrassed to call my dealer about this. When I did, my dealer and his tech did everything in their power to blame this on me and my home. They were degrading and insulting. I would have believed them except for the fact that I have a 2 story house with 2 a/c units that are sitting side by side outside. The older one has no smell upstairs at all. The brand new one they sold me has this smell that is unbearable. My father is 81 years old and on oxygen 24/7. I cannot have him here with this smell. It is so bad when we switch from heat to a/c. It took alot of our savings to purchase a new HVAC system. We got it just a few months ago and it is under warranty. My dealer will not do anything. They wont even respond to the Better Business Bureau. I dont know what to do. The more I hear and read, the smell is from them using recycled material in making the coils. That is why brand new ones smell and the older ones dont. Its just a shame. They should have to recall these things. Thanks to all that have posted here.

Dirty Sock Syndrome

April 12, 2010
Hello 'Brand new A/C stinks', Thanks, I really appreciate your kind words! Based on the online research I have done I truly believe that the Dirty Sock Syndrome is a major problem that exists in many (Not All) of the High Efficiency HVAC Units and is an industry wide problem! I also agree with you that there should be a 'recall' to require the manufacturers to fix the units that are having this problem! A new Heating/Cooling System is a major expense and after spending such a large amount of money on a new HVAC Unit consumers should not be expected to spend even more to get it to work properly! Have you been in touch with the company that manufactured your unit to let them know you have a problem? (Sometimes the Dealers might not be willing to help and if this is the case you need to deal directly with the company that made it.) If so what did they say? If not please give them a call! If you did and they were not willing to help I would not stop there I would continue to call back and speak to one of the Customer Service Managers or to someone that is willing to listen and that is also willing to help! If your unit is made by the 'American Standard / Trane/ Ingersoll Rand company I will be happy to provide you with their phone number. If not and if you do not have a contact number for your manufacturer let me know what brand unit you have and I will locate a phone number you can reach them at. Please let me know! I will be happy to help in anyway I can! I understand your health related concerns dealing with this situation for your entire family and especially with your elderly father being on oxygen! This is something that you need to stress when you are having your conversations with the company that made your unit! I wish you well in getting this resolved soon! Don't take no for an answer and "don't give up"! datgrt

Dirty Sock Syndrome

Brand New A/C stinks
April 13, 2010
Thank you so much, Datgrt. My unit is a Nordyne. I called them and they said they might supply the coil because it is under warranty, but we would have to hire someone else to get it installed since my dealer was impossible for me to deal with, which could be very expensive. They did not say anything about having it coated. But at the time I called them I didnt know about the coating. When I bought it from the dealer they stated in their 2 page ad in the phone book that their units came with 10 year parts and 2 year labor. At first when I called the dealer about this horrible smell coming from my new unit he had just sold me, they tried to get more money from me to replace the ducts. I was going to pay them to replace the ducts. I asked for a written estimate and they wouldnt give it to me. I got another opinion and the ducts did not need to be replaced at all. Then, the company I bought the A/C from acted like they would replace the coil but gave us the run around, didnt show up for 2 appointments. I missed 2 days of work. When they finally showed up they were over 2 hours late as I was about to leave for work. They said they had a new coil and was going to spray it with something when they got here. When they got here, it was a disaster. The guy that told me I needed the ducts replaced insisted the dirty sock smell had to be from me because he had never heard of Dirty Sock Syndrome before. He angrily barged into my house and started looking at my floor with a flashlite. I dont know what the heck he was looking for. I guess trying to find a dirty sock. The other guy was on the phone having an argument with someone about something unrelated to me. When he got off the phone, he was very angry and frankly I was scared of them. I am a female about 100 pounds. They left in a huff with supposedly my replacement evaporator coil and I never heard from them again. And scared to call them back. I contacted Better Business Bureau and the company never responded to them. So here I am with this thing. It is very hot here. I waited until noone else was home so the smell wouldnt hurt them and turned the thing on and opened all the windows and doors. I did this for several days and the smell seems to be subsiding somewhat. I did not turn the heater on even though it is cold here at night because it seems switching from heat to cool really sets that smell off. I will say to you again, Datgrt. You are a special person. I appreciate someone like you so much. I strive to be more like you as I am a timid person. Thank you so much for the encouragement and everything.

Dirty Sock Syndrome

April 13, 2010
Hello Brand New A/C stinks ........ Thanks again for your very kind words! It really sounds like you are dealing with a Dealer that is not willing to honor the warranty on your new HVAC Unit. It really is a shame that people like this are allowed to be in a service related business when they are not willing to provide the service you paid for! Based on the information you shared in your last note it might be better for you to work directly with the manufacturer to see if they will be able to suggest what to do if your Dealer/Installer is not willing to honor the labor warranty. I am sure that they have had situations like this before and they might be able to help. When you call Nordyne back to make sure that they are going to replace your coils with the new 'coated' type coils let them know about the situation you are having with your Dealer. Ask them if they will pay for the labor to install the new coils. If they tell you that they are not willing or able to help you with the labor/installation of the new coated coils (which I believe they should) I would suggest that you contact several other HVAC companies in your local area to get a labor estimate for replacing the coils. I understand that you don't want to have the additional expense of paying for extra labor since you just paid to have the unit installed but once you find out what the labor cost is to replace the coils call Nordyne back with this information and they might be willing to help you out with part or all of the extra labor cost. You might even want to find out this information out prior to calling them. Even if they are only willing to cover half the cost of the replacement labor the difference might be worth paying that amount to fix this problem. Believe me, I don't think you should have to pay for the new coated coils or the labor to install them but based on the situation with your Dealer it could be something that you might have to consider. (I hope not!) I have attached two links from Nordyne's Homepage. One of the links list information about the quality of their products and the other is their contact information. (I am sure that you might already have this information!) Another thing that I would suggest you do when you call Nordyne is to discuss the information that is listed on their website about the 'quality' of their products and ask them if the quality is so good why do you have the smell! You can also tell them that it is not an 'environmental' problem but an 'equipment' problem because you have another unit that is installed right beside this unit that is working fine without the smell! We use reliable parts and proven technology in our heating and cooling units. We use Demand Flow Technology® (DFT) to build high quality products for all of our customers, and are the only HVAC manufacturer certified in this technique. Each product is triple-checked at each step of our manufacturing process. Followed by 100% computer-automated testing of each product to remove human error in the final analysis. We offer some of the best consumer product warranties available in the heating and cooling industry. All warranties are manufactured-backed and not third-party administered. We manufacture a full line of consumer heating and cooling products so our contractors can match the right size unit for your home. http://www.nordyne.com/web/Manufacturing.aspx http://www.nordyne.com/web/ContactUs.aspx As I stated in one of my other notes about the 'DSS' I believe that it is an industry wide problem that impacts most if not all HVAC manufacturers and it's not just the Nordyne products that are having this problem! In my opinion (not professional opinion) I believe the problem is caused by the way the coils are made and or the type of material they use to make them. If the moisture that sits on the coils doesn't dry fast enough it is going to cause mold and that is what produces the smell and the health concerns!(My opinion!) All of the information that I have listed in this note are only my suggestions and my thoughts of what I would do or have done to resolve this problem. I would encourage you to do what you feel and believe is the best approach to take in your situation to get this problem fixed as soon as you can! Again, I would share with you don't give up and don't stop working until it is fixed. I am sure that your Dealer and maybe 'some' of the manufactures hope families that are dealing with this problem will give-up and just live with the 'Dirty Sock Syndrome'! I don't believe that is an option! I hope you are able to get some good news when you talk with Nordyne again! Good Luck! Please let me know if I can help! datgrt

Dirty Sock Syndrome

April 19, 2010
Hello Everyone, I just viewed the Radio Talk Show 'Comfort Time Live' that was aired on April 3rd of this year. The topic of the show was ........... Tom discusses Dirty Sock Syndrome, a SMELL that can originate in your air conditioning system. I thought Tom did an 'Outstanding' job in pointing out and discussing the history of 'DSS' as well as the causes and also the solution to the problem! I have attached the link to that broadcast if you would like to view it. I believe it would be worth your time. http://www.ustream.tv/recorded/ http://www.ustream.tv/recorded/ Thanks Tom, I really enjoyed listening to your show and hope that others will also find it very informative! It was great to hear your comment that Trane would be manufacturing their Heat Pumps with the new coated coil in the future! That is 'Excellent' news and I sure hope that it happens soon! Believe me, I think this is something that should have been done a long time ago but thank goodness based on what you shared maybe it will help others in the future! Thanks Again, datgrt


very mad
May 28, 2010
I just got a new Trane unit and you could smell that horrible fishy, musty smell before they installed it. I was told it would "burn off". 5 days later and it hasn't. The hvac company sent someone out to wash the coils and put some kind of antifungal coating on it. I have no idea if that has worked as it has only been one day. My question is this. We know the issue is the coil and its design and we know it makes people sick. Why hasn't anyone started a class action lawsuit? This would force the industry to supply only coated coils and the pricing for this would eventually come down as a result. Why do people have to continue to be sold "lemons" and live with the smell or get sick and go thru all these steps? Why not just do the right thing in the first place?

heater/AC smell

June 24, 2010
We moved into our new home in December 2006. We smell a chemical smell in winter and summer- especially when it first kicks on. The smell started in the fall of 2009 after we had the AC computer replaced due to a lightning strike. My sons room is right off of the AC unit upstairs and it is the worst in his room- not his laundry etc- his room faces west and it is hotter in the afternoon- it doesn't smell like stinky feet but it is more of a chemical odor- we have moved him out of the room, emptied the garage of all volatile organic compounds etc and it is not going away. The health dept IAQ man has been here and we have had the AC people here- they flushed the outside line and told us to clean the coil until they come for the annual in August- plopped a algae tablet in the drip pan- still smells. The health dept said it is mold the AC man says it is dust.

Dirty Sock Syndrome

July 10, 2010
I just bought my house last June and it had no AC. I purchased a high-end Bryant AC unit in August 2009. I bought Bryant because my house had a Bryant furnace that was two years old. I live in Minnesota. Recently I started smelling the musty, mildew smell. After researching online I checked the drain hose. It was too long and water backed up inside. There was black gunk at the end of the hose. I flushed the hose with straight bleach and the air was fresh for about a day. I trimmed the hose so that water wouldn't back up inside it. I called the company to complain about dirty sock syndrome and they never heard of it! The technician they sent to my house told me it was improbable because when the heat was on, which was located under the drain pan, all the water would dry up and all bacteria would be killed. He also told me that the drain hose was coated with anti-bacterial material. This technician was supposedly the best one they had - and this company is highly recognized in the Twin Cities and has been in business for decades, yet they treated me like some paranoid person who read scarey stories on the internet! My system was more than $4,000 and isn't even a year old yet. The techinican never turned up the system to smell the odor when arrived, or before he left! He complained about having to remove the face of the unit to inspect the coil and drip pan. I put my finger in the drip pan and smelled the water there and it did not smell at all. He made me feel rather silly! I just know that the smell returns, although not as bad as originally. I hate the smell!!! I keep running bleach through the discharge line and that helps for about one day. In May I had the heat on overnight and AC on in the afternoon, so that could have contributed to it. Basically, after reading above I think the coils are junk aluminum and have become infected! I contributed my story for those who are gathering information.

The not so mysterious smell

November 10, 2010
I knew I couldn't be the only one with this problem that just didn't make sense. If I have company over and that stink kicks in, I'm embarrassed and have to go about explaining that I don't know why it's happening. Plus the health issue is concerning. I'm glad I found this website, but I'm also disappointed to hear that the manufacturers are ignoring the problem which makes the service industry pretend like they have no idea what their customers are complaining about or pacify people with coil and duct cleaning. I keep hearing class action suit. How does that get started so that the manufacturer has to be accountable? Does anyone know? You know theres thousands of people with the same problem that have just excepted it because they were made to feel like they were the only one, or it's the sewer exhaust, or your coil needs cleaning, or.......

Make it STOP !!!

November 14, 2010
Had a new house built 3 yrs ago in the summer. Moved in Oct...When we turned the heat on it smelled terrible,kind of like freshly painted walls,musty. Had a new dipped coil installed...smell is still here, tried the lights...smell is still here,checked the duct work..smell is still here. What the heck is the problem ? I want it gone. I will gladly start a class action suit, who will join me ?

Bipolar ionization cures Dirty Sock Syndrome

November 15, 2010
We installed a bipolar ionization system into a home's AC unit in Charleston, SC. The home had a terrible case of DSS. The owner claims that the odors are gone. Google "Plasma Air" for a solution.


November 15, 2010
We got rid of the DSS last year with a coated coil, but now we have another problem since it's been installed. Red/brown colored flakes (RBF) come out of the ducts during heating season. It builds up in the internal drip pan under the coil, drys and blows out the vents. This was not a problem before the coated coil. The flakes were analyzed as not fungal or mold. A "guess" was iron deposits. From what? I think the red stuff is coming off of the coil. I don't know which is worse DSS or RBF.

class action lawsuit over DSS

November 20, 2010
I am interested in forming a class action lawsuit -my phone number is 440-668-2531


November 30, 2010
Six months ago I purchased a Lennox Elite Series heat pump/ac system for our upstairs. I live in PA, and soon after I started to use the heating , the musty smell began. Its very random. Technician came and cleaned and flushed the system. the odor came back after a day. Our 20 year old system which cools and heats the downstairs has never given us any problems. I will support a class action suit!

Dirty Sock Syndrome (DSS)

December 4, 2010
Dear datgrt, On 3/27/10, you shared your observations and experiences with this issue that, after doing extensive research myself, I agree with. You also stated that you were (ultimately) able to get a coated coil from the manufacturer. Now that more time has gone by and you have (probably) used your system during a "shoulder season" of alternating from heat to A/C in short intervals, can you confirm that DSS has not returned? Thanks datgrt, for your time and willingness to share your important details and first hand experiences.

Just started getting the smell

December 4, 2010
I have been noticing the smell for about 2 weeks and it's exactly as all of you are explaining. Only happens when I go back to AC after a period of Heat. We live in Alabama and I will be making some calls early Monday morning. I will come back and post what I find out. I have a really good home builder who also does inspections. His advice will have a great impact on what we do.

Why can't this be fixed?

December 14, 2010
I am so frustrated! 2 year old retirement (dream) home and we can't stand being inside! I have spent countless time and money trying to resolve the stinking sock smell! The dealer who installed our new units (2 separate systems; one 4 ton and one 2 ton) insisted that it was a dead animal, a heat strip, dirty ducts, mold/mildew/condensation under the house, etc, etc. Now it's been two years and several hundred of dollars spent out of pocket. I contacted Trane today and they would replace the coils; however, since it's been two years, we had to pay for the labor. We live in a very small mountain town in NC. Trane/American Standard shows the nearest authorized dealer to be in Nashville TN! When I called that dealer, labor cost start from the time they leave their office and return. Why must I pay labor? The problem should have been resolved 2 years ago by their "certified Trane Technicians"! Help please, I have no idea where to go from here.

My response from American Standard/Trane

December 16, 2010
I called American Standard/Trane for a status update regarding my DSS issue. They informed me that they would replace the coils; however, under no circumstances would they pay labor. It was not a manufacturer problem BUT an environmental issue. I have two units, side by side, only one stinks! We have no other option at this point but "give in" and pay the labor. Or, we could just cancel Christmas Dinner for our neighbors and friends. There is no way anyone could have an appetite while smiling dirty socks! I understand that during this Holiday Season everyone is totally hustling and bustling; however, come the first of the new year, I will make it my number priority to fighting the fight against these manufacturers that refuse to help. Class Action Lawsuit - I am there. Anyone know of a good lawyer - maybe one who has experienced this DSS first hand?


December 24, 2010
I live near Columbia, South Carolina and have an 8 yr. old Tempstar ultra high efficentcy heat pump and had the dirty sock problem soon after installed w/ new house in 2002. Installer came back out and repositioned it 10" out from brick wall, still problem. I have a very good buddy that i have known since 1973 that we met in trade school then. He started learning HVAC then. He had his own buisness until recently due to severe back problems. This guy is a master of heating and air! He has been out here a few times trying out different things, cleaning mildew/mold off of evaporator coils, blower housing squirrel cage, and problem came back. He said he has ideas that will resolve the problem so the unit need to be replaced. The answer is to add a fresh air damper to the blower area. As of this moment i have the panel that covers the inside house blower loose,loonened and dropped down a little to let fresh outside air to suck-up about 1/4" to 1/2" around this panel and to temporaily leave it until we get some cold nights (below38 degrees). He said if this works he will install a 5-6" dia. damper to let fresh outside air this area. As of now it's 29 degrees and it has gone into defrost mode several times and No bad smells so i am convinced that this guy has fixed this problem. Hope this can fix the dirty sock syndrone of your southern high effientcy heat pumps.


December 24, 2010
I read my response and want to correct a statement, the problem would be solved so the unit would not have to be replaced. And appolize for poor spelling throughout.

dss in orangeburg

December 27, 2010
I have DSS in a 2 1/2 year old American Standard system. Install company came out and cleaned coils, odor was back in a day. I called American Standard and they wondered why my dealer had not been in contact with the local Reps. Called dealer and he said, so you want to go with coil replacement, that will cost you. My response was, if system is only 2 1/2 years old, why would it cost me? Should I have a lawyer contact American Standard, at that he said he was through with dealing with me. If there is a class action suit, i will gladly sign on. Would not mind paying to fix problem if it was sure to fix the issue, but Trane should be held accountable for a known defective product.


December 27, 2010
Harmon I've been fighting this for years. Had it in my 1st unit. Had it for 4 years, repalced it with a new unit last year - nothing changed. Only have the smell when the unit is defrost. Would like to know more about this fresh air dampner.

DSS in 4 ton Goodman/Amana

December 30, 2010
We installed a 4 ton Goodman/Amana heat pump/LP gas back up unit this spring. Cooling over the summer was not an issue but as soon as temperatures lowered and unit went into defrost for the first time the unit omitted the dirty sock type odor. I have an excellent, cooperative HVAC guy but he'd not heard of the problem before. Sent him some research and he's willing to replace the coil. I'm trying to get Goodman to provide me the UV light at no cost and will try that first. I've cleaned the coil, to no avail. The return area has no odor but when the HVAC guy forced the unit into defrost the smell is immediate. The more it defrosts the worse the smell, increases with each defrost cycle after the first. His temporary fix was to change the default defrost cycle from 30 minutes to 90, then adjust the LP back up to be the primary source of heat when the temp is below 40 degrees. The unit doesn't smell if the LP gas burners provide the heat. This keeps it from defrosting at 40 or below, above 40 it still smells as soon as it goes into defrost. I have contacted an industrial hygeniest and advised him that our duct work has been cleaned and some replaced, the coil is dry and clean, no sign of water anywhere in the coil area. Noted that after weeks of using LP only when temp was over 40 the first defrost still caused the smell. He believes it may be something in the metal. If Goodman doesn't resolve this I'll report this to the BBB and also to my states Attorney General. I'd recommend everyone who has an issue to contact your Attorney General's office and report this issue. The Goverment is requiring higher SEER ratings and if there is a design issue, the more complaints to Attorney Generals, perhaps the manufacture's will be more cooperative to provide a solution. I also agree with some, a CLASS ACTION LAWSUIT, would be prudent. This is the HVAC manufactures dirty little secret and needs to be resolved. Final note Goodman has advised me they don't have a treated or dipped coil for coils beginning with CAPF in the model number. They also have a memo they sent out in 2005 to their reps notifying of the issue but seems to try and place the problem on existing homeowner air quality. In short the industry knows this is an issue but because it doesn't occur with ever install they have chose to keep it under the radar and not work for a permanent solution.

DSS in old units also

January 8, 2011
I live in E. Tennessee, have a 17 yr old Heil system that has been very efficient. 2 or 3 yrs ago I noticed the odor and it has gotten increasingly worse. Local HVAC contractor has come and cleaned it a couple of times but the odor comes back within a couple of weeks. My house has a crawl space that a person can stand in, and the inside unit is down there. I am wondering if that is the problem - there is no floor, so I wonder if bacteria and mold can grow more easily there and get into the coil. I am at my wit's end as to what to do when there seems to be no explanation as to the cause or remedy.

DSS in Rheem Heat Pump

January 10, 2011
Bought unit Dec. 2009. Odor started to appear Dec. 2010, it had been vague, but now is becoming overwhelming. Installer said he can clean and coat, but wants $200. If I have to do this every year I have offset any savings of using a heat pump. Manufactures should have to have a warning label on this product. From what I can read it is not confined to just one brand. Seems a Class Action Suit is the remedy, but how do you get it started.

DSS in my 2-1/2 Yr Old New House Trane XL15i

January 10, 2011
I to am having the problem with DSS. It is so bad I am concerened for our health .I called the local Trane dealer and they came out and verified it was DSS and they have ordered a new dipped coil from Trane but I will have to pay almost $900. to get the new coil installed .This problem seems to be wide spread through other brands as well . They want to make you think that it is related to the way you live in your home by saying it nothing wrong with the unit it enviromental .I think this is a problem that our goverment needs to get involved in and make the industry fix this problem before someone gets seriously sick .

dirty sock smell

jj jackson
January 11, 2011
I tried somthing that really did help and i will pass it on set the thermostat to the hottest point that you can and open windows and doors and the high heat got rid of the smell. Hope that helps you guys cause that smell cannot be healthy. jj

Dirty Sock syndrome making me sick!

Barbara B.
January 12, 2011
Has anyone had any luck with the manufacturer of Trane/American Standard in getting this problem resolved? Class Action Suit? Our Trane heatpump is only 5 years old. Noticed the smell last summer and continuing into this winter. I have allergies and have been sick more in 2010 and into this year than ever. We are considering the UV lights. Anyone have any helpful info is greatly appreciated.

Dirty Sock Syndrome

January 25, 2011
I am a service manager of a mid-sized HVAC company and deal with this on a semi regular basis. Barbara B. has asked if there is any help with the Trane product in regards to dirty sock, Trane will provide a coated coil to its customers within the limited warranty period at no cost, and is typical that the installing dealer would follow suit. However not always the case. If you have purchased an extended warranty then the installing dealer is compensated for his efforts in replacing the coil. In my efforts in dealing with this, the coated coil is the only solution that 100% corrects the problem. It is not recognized as a manufacturing issue but an enviromental one. This is across the board a problem all manufacturers are dealing with and as homes are built tighter and coil surfaces grow due to increased efficiencys this problem will continue to grow.

Dirty Sock Syndrome

January 28, 2011
I installed my Armstrong Heat pump in July. When the heating season started in November I noticed the horrible smell as soon as the unit started going into the defrost mode.I had a Carrier system for 15 years and never had this problem. Are all the coils manufactured from a generic manufacturer and sold to individual companies or do the companies buy their raw materials from the same supplier. It appears that most of the problems are the caused by the aluminum fins on the copper coils supporting the growth of bacteria. Is there really any cure other than replacing the coils

cure for dirty sock smell

February 28, 2011
wear a heppie mask for the initial startup then get used to the odor!

DDS. Smell in New HVAC

What to do.
March 4, 2011
This is a class action lawsuit begging to happen. This should not happen to new HVAC unit and people given the same humilating excuses and even use it to squeeze more money out of you. Contact some of the attorneys that sued the tobacco companies and breast implant companies. See the other page on this site where many others are experiencing same problem. Serious illness can occur from possibly breathing this smell. Find a way for all to leave contact info so lawyers know who to contact.

Dirty Sock Syndrome - Update 3/26/2011

March 26, 2011
Sorry for the very late response to your note! I have not been back on this site in several/many months and I just checked it for the first time again this morning. --------------------------------------- Title: Dirty Sock Syndrome (DSS) By: kh Posted: December 4, 2010 5:45 AM Dear datgrt, On 3/27/10, you shared your observations and experiences with this issue that, after doing extensive research myself, I agree with. You also stated that you were (ultimately) able to get a coated coil from the manufacturer. Now that more time has gone by and you have (probably) used your system during a "shoulder season" of alternating from heat to A/C in short intervals, can you confirm that DSS has not returned? Thanks datgrt, for your time and willingness to share your important details and first hand experiences. --------------------------------------- As I stated in my earlier posts our new coated coils were installed one year ago on March 27, 2010. Since that time we have not had any problems with the 'DSS' smell! I really believe this fixed our problem and hope and pray that the smell never returns! We have been very pleased with our Heat Pump since the new coils were installed! As I also stated in my posts from last year American Standard / Trane replaced our coils at no charge and we had a 'Great' installer/dealer that did not charge us any labor to change out the coils. Again, sorry for the late response to your question! I hope this information helps! datgrt


July 6, 2011
I had a new Trane installed in March 2010. DSS started in Dec. 2010. My installer insisted that I needed a UV light at an additional $400. After reading this forum and other articles, I decided I needed a coated coil. I had a small problem with Trane but they agreed to provide a coated coil, since the unit was less than a year old, if I paid shipping. I think they should have foot that part of the bill also, but I figured I'd fight that battle another day. Even though I had a 2 year labor warranty, and Trane emailed me saying that I should NOT be billed for the installation, my installer would not order or install the coil under the warranty. Central Florida BBB went along with him. I have received the coil and paid $450+ shipping to have it installed by a different Trane dealer. Trane would also not support me against their dealer. Don't believe that great customer satisfaction blurb in their brochure, it means squat. I won't know until winter whether or not it works.

Dirty sock or coil

July 14, 2011
After 13 years of discomfort each summer and thousands spent!!! Thinking I had Dirty sock syndrome or a dirty coil Great news, the plumber found the source of stink (sewer gas) entering my house via positive pressure. Plumber did smoke test on sewer line today, be for any work was started. It revealed that indeed the sewer gas was not making it past condensation p-trap, but was coming from a uncapped T in the vent stack that was intended to be used to run A/C condensation line when house was built and a unit installed 30 years ago. That said stink is no more! "So sad, but so true "

Evaporator coil smells

November 20, 2011
I wish this wasn't true but the coil odor is certainly not limited to seasoned coils. We had the smell happen 1 day after new install of a Trane duel fuel system. After fighting with the HVAC contractor, the Trane rep authorized a dipped coil, but after 12 weeks of waiting for it, when installed and cycled, my wife and I were outside and severely nausious/lightheaded within 15 minutes, horrible chemical/paint smell. That coil was removed and a third coil was installed after it had been treated with anti-fouling solution, but the smell is still here. It has been 3 months since we bought the new system, our home is almost 20 years old and we lived here for 3 years with the original Lennox Pulse furnace and separate AC unit system with absolutely no odors. We don't know what to do next.

October 10, 2012
This guy found an easy and inexpensive cure for Dirty Sock Syndrome: http://www.youtube.com/watch?v=VclGuogRPCY It worked for me. Pass this on.

Theory as to cause of DSS

David from NE
October 20, 2013
My wife and I spent three years suffering from DSS too, and maybe it is just a coincidence, but while we were breathing this moldy air, my wife was diagnosed with stage 4 ovarian cancer (at age 39). Anyway, she is still with us (3 years later, which is considered somewhat of a miracle), and we are putting in a new system in a different home, and want to avoid the same problem. In order to try to figure out what the problem was when we were living there, I did a lot of research to educate myself on HVAC issues, and truly have a better understanding of HVAC principals than most HVAC contractors I have met (I am a physicist by training so that helps). I am not being conceited here; this is not a reflection on how much I know, as much as how little many of these contractors know! Can you relate? Anyway, how many people reading this have had DSS happen with a heat pump (most I assume), and just as importantly, how many people have had this happen with a heat pump where the coil is BEFORE the blower motor? If you have electric backup, you would probably have the coil before the blower motor, and if you have gas backup you must have it after the blower motor. I am quite sure that one of the main causes of DSS is that, when the coil is before the blower motor it is under negative pressure (meaning that air is being SUCKED through the blower motor as compared to being PUSHED through it), and so water may not drain into the condensate line properly. This keeps moisture on the coil and can cause mold problems. So I am taking a poll here to confirm this theory. So please respond if you have DSS and tell me: 1) Do you have a heat pump? 2) Is your coil before or after your blower motor? If you don't know, just tell me whether you have electric or gas backup, and I can most likely deduce the location of the coil relative to the blower motor from that. 3) What brand do you have (I am theorizing this is more common with Trane). Thanks!

Poor trane owner

Ronald Williamson
November 6, 2013
I had my old trane replaced in June 2013. The air handler is a TAM series that pushes the air rather pull like older systems. There was no odor all summer until the need to switch between cooling and heating in early fall. That is when we noticed the smell. It smelt like wet drywall compound and maybe paint with high voc in it to dry. As to to dirty socks maybe. They cleaned the coil with with a cleaner. If we run nothing but heat no smell until it goes into defrost. So it is at point of heat going to cooling.


November 9, 2013
I have a hybrid Westinghouse system manufactured by Nordyne. I had it installed in 2010. I also had my dealer install new ductwork as well. For the first two years I didn't have any issues with odors; however, now I'm afraid I have the dreaded DSS. I started noticing a musty odor this summer when I turned on the A/C. I called the Dealer, and he sent someone out. The tec guy took the panel off and said that he couldn't see any issues. He also said that he could not smell anything. Hah! I guess he had a stopped up nose that day. He did nothing, and the smell is now worse since I have turned on the heat. The unit I replaced was a Reem heat pump with electric coil back up, and I never had a problem with odors. I paid a lot of money to have this new system installed, and I can't believe that a system that is just three years old smells this bad. My unit is gas, so the blower is before the coils if that helps. After reading this I will be calling my dealer back!!!!

Member Member
November 12, 2013
We built a new home in 2012. After moving in, we bought a new table & chairs for our kitchen. After smelling this horrible dirty sock smell for the last year in just 2 rooms of our house, I couldn't figure it out. (I seriously thought that maybe one of the workers had left a dirty sock in the vents!) But just the other day, a light went on ! It's our brand new table and chairs in the kitchen and the 2 chairs that I store in the baby room. After putting my nose to the chairs, I know its the stain on our table & chairs. It is so disgusting and has nothing to do with our HVAC except that maybe you smell it more when the air starts circulating. Not sure what I'm going to do but I'm wondering if anyone else has discovered this.

firgured it out 2days and no smell

November 27, 2013
what I did 2 days ago is move my auxiliary heat strip on the return side of the unit so that the temperature would get high enough to kill the bacteria that builds up in the coils and so far it has worked. took me about 2 hrs. I have a 2yr old tempstar package unit 3ton. I could not believe the smell of a brand new unit had put off and the many cases that are out there. it is only in the units that are more efficient and the aluminum strips are closer together. so I guess try it. who ever has manufactured this problem of a more efficient coil should be responsible I believe.

Response to David NE

Kathy in central Texas
November 29, 2013
Responding to David in NE re: Theory as to cause of DSS: we have a Trane unit and the backup is electric, so it seems to fit with your theory of pushing vs pulling the air. The odd thing is we've had the unit 8 years and the odor just began two weeks ago when the temp dipped into the 30's for several days (unusual for here) and the heat pump began running a lot. I thought it was the auxillary heat strips coming on to supplement the heat pump (happens when it is extremely cold) and that it was the 'dust' on the strips burning off (from not being used for a year). Wrong! Strangely, it is not every time the heat pump comes on that the smell is present, but it is disgusting when it does. I'm not sure where to go from here.

Reply to Dave in NE

December 6, 2013
For you poll: Installed Trane heat pump (electric heat) in June. Got the smell in October while running the AC after a hiatus of several weeks (but only once); got the smell, last night and again today, while the heat was running. ... Does anyone know if a class action suit has been initiated yet? I've never sued anyone in my life, but I'll join a suit if my installer can't come with a fix that doesn't cost me more money!


December 12, 2013
We have a new home that started having the smell after the first six months. The coil was replaced in the unit in the attic, and here we are another six months later and the smell is back and worse than ever. I have been informed that this time they will be replacing both the unit in the attic and the one outside. I am keeping documentation of everything (and have put them on notice) in the event that I have to bring a lawsuit. There should be a class action against the manufacturers. This is probably making many people sick and they don't even realize why. Shocking that with the advancement of technology today they can't find a solution for this.

at wits end

Member Member
March 7, 2014
hi, hoping someone can give me direction. i began smelling a musty odor coming from the ac vent when the air kicked on. this was strong enough to actually wake me at night. it got so bad i started having severe headaches, sinus issues and general poor health. the ac was checked and coils cleaned,, smell persisted. then we had the ENTIRE SYSTEM AND DUCTS replaced. i was hoping my problem was gone but its still here and i'm out 7k dollars. the smell is prevalent in only two rooms. any suggestions?? i'd appreciate any advice from someone who has found relief from a similar problem

Reply to "at wits end"

Member Member
April 11, 2014
If you had your entire HVAC system and ducts replaced and still have the problem, I have to believe the problem isn't in your HVAC system. In that case then problem might be mold or a dead animal someplace. If it is a dead animal, I would think that over time the smell would subside. I had a similar problem, but haven't replaced everything yet. I did have the evaporator coil removed from my system and that fixed 95% of the problem; I suspect there is still a small some of the bacteria, or whatever was growing on the coil, lingering around. I haven't replace the evaporator coil yet.



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