Fish Smell Coming from Central Air Conditioner

by Homeowner
(Long Island, New York)

All last summer a strong fish smell seemed to be coming from our mud room (no a/c vents in there, but there is a trap door in the ceiling to the attic which right next to it is the central air conditioner system). Adjacent to the mudroom is our den which has 2 a/c vents.


The smell is pretty strong in there too, although it seems stronger in the mudroom. We never figured out what the smell was and hoped it would just go away. The smell only came when we turned the a/c on and no other rooms (aside from the kitchen which is next to the den) got the smell.

Today we turned on the central air conditioner unit for the first time of the season and it had the same horrible fish smell from last year. My husband went up into the attic, there was no smell by the a/c unit, the condensate pan did not smell either.

Years ago we had a problem with the pan not emptying well enough due to the lack of incline and it would leak over the side through the garage ceiling. But it was corrected we think and has not leaked through the ceiling since.

We were thinking today that maybe an animal got into the duct work to the den last summer and died (doesn't explain the mud room smelling though) so for lack of a better idea, my husband went to Home Depot and bought new ducts, which he replaced today.

BUT, after the new ducts were in, we turned on the a/c and the smell was just as strong. We are out of ideas and hoping you may have a suggestion. Any insight will be much appreciated!

Thanks so much.

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Sep 29, 2016
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Fish smell/electrical issue NEW
by: Anonymous

Horrible rotten fish odor suddenly coming from two heat pumps. Cleaned filters, no luck. Read these posts, could not find any electrical problems. A week later, smelled burning plastic from ceiling fan in neatby bathroom. Motor was shorting out, so we turned off circuit breaker. (This was happening while light/fan switch was OFF.) Replaced fan, fish smell gone.
Learned that overheated plastic gives off trimethylamine or a similar substance that is also given off by rotting fish. Gas is in walls and ceilings and is blown into house interior when heat pumps arr turned on. Thank you to everyone who has posted to this site, you have saved us from a probable house fire.

Sep 06, 2016
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I was increduluous... and wrong! NEW
by: Ash

Several years ago we got a big (15,100 btu/hr) window unit. At first it would heat up all the outlets and pop breakers with reckless abandon. Eventually I moved stuff around so it was pretty much all on its own on the back room breaker. No more hot outlets - in fact only the outlet it was plugged into even got warm. 2 days ago, fish smell in the bedroom. I figured it was something growing in the condensation pan of the unit or something. Found this post, checked the outlet it was plugged into... warm, no real smell. Pulled cover, looked fine. Checked all the other outlets in the room, all cool. Thinking to myself, I could have sworn there was another one in here somewhere, ah yes, behind the chest in the corner - REALLY HOT. MUCH stronger smell. Pulled cover... REALLY STRONG smell. Killed breaker, pulled out outlet, the neutrals were melting together and the "white" they're supposed to be was brown for 6" up. Amazing!

Aug 31, 2016
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Fishy smell in room/outlet NEW
by: Anonymous

Smelled a fishy smell tonight right before bed. Thought it was an AC coolant leak and went online and found this blog. Just as described, it was a melting electrical socket in my daughter's room. This site may have saved our lives and prevented a serious house fire!! Changed the socket and all is well!! Thanks so much!

Aug 06, 2016
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Thanks NEW
by: JJD

I too had the Heat and Air Company out looking for the smell of bad fish. After seeing your column I had the electrician look at the panel. The breaker was so fried we could not remove it from the panel. When we did remove it that was the smell. We replaced it and finally all is good. Thank You. JJD

Jun 28, 2016
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Thanks! NEW
by: Anonymous

I was seriously skeptical despite all of these posts because I've never had electrical problems before, but sure enough, when I checked all my plugs instead of checking the actual A/Cs I found the source of the smell. A nightlight was beginning to turn black on the backside even! You guys may have just saved our lives, thanks for keeping this thread going!

Jun 13, 2016
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AC FISHY SMELL NEW
by: Anonymous

Our mud room smelled horrible.and the smell got way worse when the AC kicked on...I mopped the floors and wiped the walls several times and couldn't get the smell to go away. We were baffled so I googled it and found this post. My husband went directly to the panel nd OMG we found the source!!!! It was literally minutes away from ignition!!!! We shut it all down and are calling an electrician......THANK YOU FOR THIS POST.....IT SAVED OUR HOME AND POSSIBLY OUR LIVES!!!

May 10, 2016
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AC giving out foul smell, the 3 pin was cooking up, couldn't take the load. NEW
by: Anonymous

1st check the plug, n other lights, appliances in the room, In our case we even get our AC serviced, got the cooling gas changed as well, but the next day again we had that foul smell coming from the AC.
After reading the link given as source, I found that we were using a 3Pin so that we could charge our mobiles, laptops at the same time. That 3 pin could not go well with the AC load and had started cooking up(burning). even after it was off, when I inspected, the 3 pin was crazily hot and the material seemed fused, I removed that thing (3 pin) and the AC worked totally fine after putting it directly on the board, the way we used to switch it on since last 2 seasons. it was such a big problem since 10 days, this link saved us!!

Apr 14, 2016
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took me 30 seconds to know the source of the problem after reading this thread! NEW
by: Anonymous

Faced the same exact problem. Left home for two hours and came to a very strong rotting fish smell. It was concentrated in my bed room and inside a cabinet in the play room next to my bedroom. We also thought something died in the AC ductwork, since the smell got stronger when the AC started working.
I was discussing it with my husband and wondered if could be a leak in the refrigerant so I researched if the refrigerant smells like dead fish. It all made sense to me why the smell was stronger in the display cabinet, it was because we used this cabinet to cover the electric panel. Moved the cabinet and opened the panel and that was the source of the smell. Switched the breaker off and in the morning called the electrician for him to come and say, the main fuse is melting.

I would've never thought, not in a million years that fish smell was related to electrical issues. Thank you so much for this thread. Truely a life saver 🙏

Jan 19, 2016
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smelly dead fish in our office NEW
by: Anonymous

thanks for this blog. we have been having this smell in our office for months now, we even changed the aircon.. its only today after reading this blog that we have found the source...the smell is coming from the breaker box, I have just called the electrician. I am so grateful guys for sharing your experiences with this... May God bless you all!

Jan 09, 2016
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fishy smell from our furnace NEW
by: Anonymous

Thank you for starting this blog, and for everyone that added their comments...I must admit that I raised an eyebrow in disbelief when I was reading but as weird as it sounded we found that our "fish smell" was our transformer next to the blower on our furnace that was all blackened and wires melting. THANK YOU EVERYONE for your posts!

Dec 18, 2015
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Fishy outlet NEW
by: Phil Melton

Thank you for his blog and we did exactly what everyone said and went and checked outlets and we found the problem ! This was very helpful and Google is a wonderful thing!!

Sep 01, 2015
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This post is a life saver!! NEW
by: Anonymous

This post saved our lives as well!!!!! Even our air conditioning unit worker who has been fixing AC units for 30 years didn't know about this! My Dad learned about this from your post. He went into our circuit breaker and saw that it was BURNT! Without this post we would've just looked at our AC unit and figured and animal died inside or something of that nature. Thank you so much for posting this!!!

Aug 02, 2015
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Dead fish smell in A/C - electrical fire NEW
by: A Schonhofer

This post saved our house from catching fire. Seriously! We moved into a "new to us" home 2 weeks ago, built in 1979. we were sitting in our family room watching a movie around 1pm, when all of a sudden the smell of salty dead fish began to permeate the air. We went around smelling vents, and it was just gross. Thinking something had crawled up in the A/C and died, or that something with our saltwater pump for our pool right next to our slab leaked into the vents...we checked both the pump and the furnace/ductwork room in the garage..that room was super smelly. Upon walking back into the house from the garage, my son asked why the light in the fridge was out....hmm..that's odd. ...I told my husband, and he was in the middle of something else, so while I waited on him to go flip the breaker for the fridge, I Google the smell in the A/c and thank God I did. Found this post almost immediately, and when I told my husband, he said "no... I've never heard of such a thing!" But we went smelling outlets, switches and then remembered the breaker needed flipped....man oh man, the breaker box was the most concentrated smell. We knew then the post might be right, so we called the home warranty company to send an electrician. Took them 2 days to get here...meanwhile, we're so nervous we're making our kids sleep on the other end of the house on the floor of our bedroom since their bedrooms are right above the garage where the breaker box is. The electrician found 2 seriously burned out breaker boxes, and the main house wire had smoldered....I don't even know how we had power. The electrician said he couldn't believe how bad it was, and said we were very very lucky our house did not burn. He changed the entire breaker panel, so we're golden now. Had we not seen this post, and realized the correlation between THAT smell and electrical problems, we probably would have had a house fire within a few days since the panel was just sitting there cooking. I spoke to several electricians, and NONE of them knew what I was referring to about the smell being a dead or fishy smell....one said he never heard that before. THANK YOU to everyone who posted on here...we feel like this saved our lives,

Jun 28, 2015
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It was the Emergency Shut Off Switch NEW
by: Anonymous

I just ran into this problem over the past few days. Every time the central A/C was on there would be a strong odor of dead fish at the top of the basement stairs. There was no odor coming from the unit, just at the top of the stairs. There is an emergency shout off switch just above the light switch. Sure enough it was hot to the touch. When I took of the switch plate it was melted. Changed the switch and no more order.

Jun 09, 2015
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Portable Air conditioner NEW
by: Anonymous

Hello, I bouht a delonghi Pinguin air conditioner. It is a portable version. The fishy smell was awful in my case and the air conditioner was new. I thought it was my cooking vents over the stove that was smelling fish. After reading what people left on the blog i decided to check my circuits. The smell was originating from another plug that was beside the one that my AC was plugged in. The AC plug itself was not hot and that particular circuit was not smelling. But when i touched the other one, it was burning hot and smelled fish. Very dangerous! thank you for all of your comments, you probably saved my life.

Have a nice day!!

Jun 03, 2015
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Thank u soooo much for this post! NEW
by: Anonymous

Took me 1yr to fund this post, I have googled this problem so many times it's not even funny. I would describe the smell as dead animal not fishy but maybe dead fish would apply. I had a can light go bad and it was melting the plastic, then the AC return was right next to it so the smell WAS technically coming from the air vents, I never thought the smell could have originated outside the duct work do to the intensity of the smell only when the AC was on. Anyways problem solved thanks again for the post, I will sleep so much better now, not being concerned of some weird animal crawling into my AC duct work every night.

May 29, 2015
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fishy smell NEW
by: Ray

Had the bad fishy smell every time I turn on my air conditioner. Went on line and saw a lot of people were having the same issue. They had called an electrician So I did that first being I just had all the vents cleaned. It turned out to be the fuse box. The plastic on the fuse was crumbling. Problem solved. It dose sometimes comes from an outlet if the wires are melting. But you ill smell it stronger in one area compared to others and the fuse or an outlet will be hot to the touch.

May 19, 2015
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Smell from AC unit NEW
by: Anonymous

I have the same problem. I just went to Bob Vilas site and think he has it figured out. Please read it The problem with the AC could cause a fire.

Mar 30, 2015
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Fish smell when the heater cycled off. NEW
by: Benarah

I noticed this last winter season. I only have this happen when the heater in our apartment would cycle off. Only in the master bedroom and nowhere else. I, like no doubt others with this problem, wandered around like a hound dog sniffing the air to try and pin point where the smell was coming from.

Thinking it was the vents or the heating unit, I informed the manager and they did a duct cleaning. First cold spell, this morning, and I smell it again, literally only moments ago. Got online, I read this post, went to check my breaker panel and sure enough, it had the fish smell strong! Good call, whom ever figured this issue out.

Dec 26, 2014
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Friday Fish Fry? NEW
by: Madison Georgia

OK get this. We just switched from a propane furnace to a heat pump. I've noticed when the heat first runs after not being ran for a shirt while or following the AC usage, that it smells like I've been cooking fish. My house is 70 years old and was rewired without a permit 3 years ago. The wiring looked kosher to the building inspector. Now I'm wondering if I'm smelling something electrical? But why only when the heat is ran. For instance when it's coming on tonight it's fogging up the windows and making that smell. After it runs for a while, the house dries out and the smell goes away. But only if it runs regularly, like every hour or so. This is so weird! It started with the new heat pump. The old set up had a different chemical smell when the AC initially came on and steam when the heat came on. Now it's all new ducts, 10% leaks, but the house is old and drafty in places. What am I smelling?

Oct 10, 2014
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Happened to me as well. My house almost caught fire NEW
by: Emrldjade

I experienced the same problem. Unfortunately, when I searched the internet I could never find any info or this site until I found the problem myself. I too, was puzzled as to why it smelled like fish. Like you, I did find a link between the window a/c and the smell but couldn't figure out just exactly why. Until yesterday, I had just got home and it was hot my daughter had volleyball practice and was really hot so we turned on the A/C. I walked into the bedroom right next to the living room ( where the a/c is) and the smell was awful. I had already determined the smell was not directly from the a/c and figured out it was electrical though and plugged the a/c into a different receptacle. Even after that the smell was still present I went into the bedroom and looked at the out that was on the opposite side of where we did have it plugged in. It was glowing ember red and looked as if it was on fire. I told my oldest daughter to get the fire extinguisher and I turned off the A/C although it was plugged into another outlet. The red glow went away. Nothing was plugged into that outlet or the one directly on the other side of the wall but it was almost on fire. I am still in the process of having it fixed. I will post again to update and let you all know what exactly was the problem and the solution. Please be very thorough and cautious when dealing with over heated outlets and check all of them whether they are in use or not. It could cause a fire as I found out yesterday. I immediately unplugged everything on that circuit and it finally became cool enough to touch. Before I went to bed I turned off the breaker to that particular circuit of the house. Just a precaution. If anyone can let me know what it is before I call an electrician it would be appreciated. Thank you.

Oct 10, 2014
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Happened to me as well. My house almost caught fire NEW
by: Emrldjade

I experienced the same problem. Unfortunately, when I searched the internet I could never find any info or this site until I found the problem myself. I too, was puzzled as to why it smelled like fish. Like you, I did find a link between the window a/c and the smell but couldn't figure out just exactly why. Until yesterday, I had just got home and it was hot my daughter had volleyball practice and was really hot so we turned on the A/C. I walked into the bedroom right next to the living room ( where the a/c is) and the smell was awful. I had already determined the smell was not directly from the a/c and figured out it was electrical though and plugged the a/c into a different receptacle. Even after that the smell was still present I went into the bedroom and looked at the out that was on the opposite side of where we did have it plugged in. It was glowing ember red and looked as if it was on fire. I told my oldest daughter to get the fire extinguisher and I turned off the A/C although it was plugged into another outlet. The red glow went away. Nothing was plugged into that outlet or the one directly on the other side of the wall but it was almost on fire. I am still in the process of having it fixed. I will post again to update and let you all know what exactly was the problem and the solution. Please be very thorough and cautious when dealing with over heated outlets and check all of them whether they are in use or not. It could cause a fire as I found out yesterday. I immediately unplugged everything on that circuit and it finally became cool enough to touch. Before I went to bed I turned off the breaker to that particular circuit of the house. Just a precaution. If anyone can let me know what it is before I call an electrician it would be appreciated. Thank you.

Sep 02, 2014
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fishy smell - incredibly grateful to Richie for his post NEW
by: Narli

it was in the circuit breaker box. it was melting and smoking and we never would have found it in time but for Richie's post to check electrical stuff. We were searching ducts and coils etc. Owned so many houses in our lifetimes, never heard of or experienced anything like this. So So grateful for this forum and his post in particular. narli

Aug 28, 2014
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Fish smell NEW
by: Anonymous

Oh my goodness. Thank you for putting this post together. I have spent a year trying to figure out what was wrong with my AC unit and why it smelled like fish. Had the airducts cleaned and had multiple AC companys come out to our house and walk away stumped as to why two rooms in our house smelled like fish when we turned on the AC. After reading this blog about the electric issues I thought everyone was crazy. But I went ahead and went into the room and started smelling the plugs and the light switchs to see if the smell concentrated near them.... And nothing. Then I looked up at my light fixture and got on a ladder and pulled it open and the smell overwhelmed me. Bingo. Found the problem and feel like I won the lottery.

Aug 28, 2014
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Fish smell coming from Central Air conditioning NEW
by:

Yes, just had this problem resolved successfully by replacing the entire AC coil. The fishy smell would come on strongly after the unit would be turned on. Cleaning the coil with chemicals, available commercially, did not help. Nor did it help putting special bacteria-fighting pills into the coil pan. The ONLY way to get rid of this horrible smell was to replace the AC coil.

By the way, don't be surprised if your HVAC technician is not aware of the "fish-smelly coil" problem. Apparently it is not a very common problem they encounter.

Jun 17, 2014
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Space Pak system smell sickens me NEW
by: Anonymous

Not having traditional duct work in the house,I had a new space pak installed (where the unit is outside and the air handler is in the attic, and the round ducts come off the air handler, and drop into the various rooms). In the fall, plugs were put into the air drops in each room so that warm air would not rise into the duct work. The next spring when the technician came to open up the system, this HORRIBLE "fishy" smell came from the ductwork. There had been NOTHING electrical turned on...the AC system had not been turned on at all...so NO electrical involvement whatsoever.

The firm replaced all of the ductwork, and everything was fine for that season...no smell. At the end of the season, I ran the system for 4 straight hours to make sure it was completely dry in the ducts, then plugged them up for the winter. Next spring...minimal smell...all was fine. That fall, ran the system for 15 minutes only, on advice of technician, then put in plugs for the winter. This spring, without turning ANYTHING on, only removing the plugs and the cover from the interior air return, the smell just about knocked me over. The technician came up, opened the system...whole house stinks. They are one of the most respected firms in the city, but they have no idea what the smell is. I'm told I am the only one who has had this complaint. From all the activity I see on this topic on the internet, I don't think I'm the only one.

It's definitely not electrical, because absolutely nothing was turned on. Coincidence...my daughter was looking at resale condos, and when we walked into one, there was the SAME smell.

HELP!!!!!! please.

Jun 12, 2014
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Stinking Scallop House NEW
by: Stinkyhouse

THANK YOU to whoever started this blog! We have dealt with smell of "stinky scallops" for hmmm....years - at least 3!
I finally read this, then checked the breakers, then went to the stinkiest area - THE KITCHEN. Loen behold, our double light switch with a dimmer was SO hot! I just about burned my finger on one of the screws. Hubby read your blog & pulled the switch & there it was - black woodwork, crispy coated burnt coating on wires.
THANK YOU for probably saving our lives.

May 13, 2014
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I need help with fishy odor NEW
by: Anonymous

I have read this entire posting and I am confused.
1. Why does the smell present itself ONLY when the A/C is first turnred on ? It disappears after about 20 seconds and the smell is much worse when the attic is hot and the A/C comes on.2. My panel(s) are outside as are my central A/C units, they do not have odor when I go out to smell them.
3. Is someone saying that the electrical wiring going to an outlet is the issue even if there is nothing plugged into the receptacle ? I have gone around and none of the receptacles (or light bulbs) are hot nor do they have an odor. My lights are of the cannister type.
4. This smell only is present on the right side of the house (one of the A/C units, specifically in the kitchen. Coincidentally the night after my wife made scallops di we get the smell.
5.I am totally stumped and I do not want to start investing hundred of dollars (maybe even more) to resolve this.
6. ANYONE HAVE ANY COMMENTS.

Jan 25, 2014
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Fish Smell From Vents - SOLVED NEW
by: Richie

Fish Smell Problem Solved, look no further! I would like to save you the hours of research I had to spend on resolving my "fish smell" problem coming from my air vents. Know that 9 out of 10 times the strange fish smell is coming from a burning electrical outlet or wire or a circuit somewhere in the house. I know it sounds strange, but I've learned that most electronic shielding and plastic components are made with a certain kind of chemical that makes it high heat resistant. This chemical in the plastic releases a strange "fish" or "urine" smell when it's cooking. I spent hours researching this and found that almost every single person that mentioned the "fish smell" all came to the conclusion that there was a cooking electrical outlet, wire or circuit somewhere in the house. In my case, the odor smelled like a combination of fish and urine. It was horrible. I was convinced that a mouse got into my air ducts and either urinated or died. No one could talk me out of this theory at the time. I read many posts and laughed at the people claiming it was an electrical problem because I'm familiar with the unmistakable odor that comes from burning electronics that has no similarity to fish or urine. Well sure enough, I found the problem. It was a cooking circuit breaker in my circuit board cabinet. Apparently, my central air HVAC system was working extra hard to keep the house warm during a brutal cold front for several days. This caused the circuit breaker to overhead and cook. I had an electrician swap it out for a new one and the smell was gone. Total cost $65.00. Before finding where the smell was coming from, I was ready to spend thousands on exterminators, air-duct cleaning and air-conditioning heating company to service my unit. Wow was I relieved the problem cost me so little. My advice to anyone with the infamous "Fish Smell" should start by smelling the breakers in the circuit board and then work your way to smelling every single electrical outlet in the home including light fixtures on the ceiling. There's definitely something cooking somewhere and you'll find it. If not, then that's not good because you probably have an electrical wire cooking somewhere in the wall and that can cause a fire. Well, hope my story and advice will come in handy to someone out there with the same problem.

Jan 09, 2014
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Fishy Smell when Heat and Air comes on NEW
by: John J

When my heating unit would come on there would be a fishy smell. The smell was stronger in my master bathroom than anywhere else, but it could be smelt through out the house. After reading the other comments I checked the lights and wall receptacle. The wall above the receptacle was hot and upon further examination I found one of the wires was loose and the wire insulation was burnt. I temporarily fixed the receptacle and problem solved. Thanks to all and hope this helps someone.

Aug 16, 2013
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Fish smell NEW
by: Ivann

I live in Mexico and I got my 5 ton York unit 2 years ago. It took me by surprise that for the las two years I've tried all kind of crazy things to fix this issue. I even had a huge fight with my wife because I did not wanted to buy this unit but my wife did so as always girls win all the time. I'll confess that I'm been enjoying blaming my wife for this bad smell for the las 24 months even when my mother in law comes to visit us or friends I always say welcome to our stinky house just to bother my wife anyway... After I audit all outlets I found that the smell comes when I have my tv on, my fan, some lamps and of course the damned AC unit. After a few days of testing it turns out that the power wire wasn't the correct one, I replace the wire and also change breakers... Smell gone and happy marriage thank you all...

Jul 19, 2013
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Light fixtures can stink ... NEW
by: Anonymous

We dealt with the fishy smell problem in our new house for about five years. It only happened in the summer when the AC was on .... The smell was so strong at times my son wasn't even able to sleep in his his room at night...:(

I had read that older homes can get this she smell because of old wiring… But had no idea that even new light fixtures could have bad wiring that would set off the stink. P.U! It only happened in the summertime because these ceiling mount fixtures were on the second floor and when the roof got hot, so did the wiring... And when we turned the lights on, that's when we would smell the smell. We assumed for five years it was the air conditioning .... We had the ducts cleaned, the Coils cleaned, the trays cleaned, had Blue lights installed on the coils ...our crawlspace cleaned…
It was siimply the ceiling mount light fixtures. After replacing those… the smell is gone.

Hope you can get your problem resolved soon…I know how frustrating it is.

Jul 19, 2013
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Suggestion confirmed NEW
by: Kevin

I was about to call an a/c specialist over the weird fishy smell seeming to come from a/c vent; weird because it was only happening in one room and only at night.

With the suggestion to look at electrical, I removed the cover from the room's overhead light and found what looked like old flypaper that was slowly cooking each time the light was turned on and I guess had gotten to the point where it was smelling as bad as it did while seeming to come from the adjacent vent.

Flypaper (or whatever it was) removed, smell gone. Really helpful page.

Jul 05, 2013
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Bad breaker NEW
by: Anonymous

Fishy smell intermittent for 9 months, only with AC on. Had it serviced in the early fall and all was well for months. In spring, the smell was back. As we had some duct work needed, that was done and smell was gone for a month. Then hottest day so far (112), it started again. Then the unit decided to not come back on after a power outage on the same day. Wondering if there was a correlation, I did some research and came here. Found some hot breakers in the house. Went to check on the one for the AC and it was wicked hot. Husband pulled out the breaker and it was partially melted. The breaker hadn't tripped, it just melted. Thanks for leading us in the right direction. New breaker installed, but will still have unit checked out. So far no fishy smell. Happy 4th of July!

Oct 01, 2012
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Electrical NEW
by: Anonymous

I thought my ac had a freon leak but Thanks to this website I figured out it was a light bulb that I had just replaced. It was burning the light bulb duct. I also cleaned the drip pan drain tray to the ac unit...it was also dirty but the smell was coming from the light bulb duct from the kitchen... My other rooms didn't have that smell. Again thanks and TTG for Google Search!

Jun 20, 2012
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Fishy smell when AC comes on NEW
by: BRB

WOW, We have had the problem for a long time. Thought it was an AC unit problem that we have chased for three years. Happens only once in a while when the air comes on. Strongest smell in the hall, back of the house. After reading tonight online, we were led to checking light fixtures in the hall??? Guess what. One two bulb glass bowl dome light, we removed the dome to find two clear 60 watt bulbs and Man that was it. The smell of over heated wire(FISH)was unbeleivable when you smell the inside of the glass dome it was obvious. Always seemed like it was coming from the vents, and it was, as it was pulling the smell into the return ducts. Go to where you are getting the stongest smell, and check your electrical, lighting, bulb watts. We are going to frosted 40 watt bulbs in all ceiling lighting with glass domes. Lucky we did not have a fire.

May 20, 2012
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Electrical here too NEW
by: InIdaho

We experienced this problem for the first time tonight - the A/C kicked on and suddenly the vents in our den were putting out a terrible fishy smell. I thought dead animal but after reading the posts in this thread, my husband and I check outlets all over the house and found the culprit in the kitchen - hot to the touch. We shut it down at the breaker, opened it up and found melted wire. It smelled fishy. We capped it off, will replace it tomorrow. Turned the A/C on and the smell is gone. I'm not sure how this kitchen outlet is connected to the vents in my den but it seems to have been the issue. Thanks to all who posted!

Jan 27, 2012
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Fishy Smell in our house (comes and goes)
by: Anonymous

OMG please whatever you do check your electrical sockets FRIST just found the problem the fishy smell is gone THANK GOD!!!!

Jan 21, 2012
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Fishy smell in my home
by: mark and nikki

Had have been experiencing the exact same problem for years until now. It appeared to be noticeable only when our central air cycled on however i did notice that it was not all the time. Very incostitant so i kinda ruled out the AC and the ducts and nevey really worried about it much after that. We just lit an oil and paid no mind to it when the smell did arise. This was easy for us to do because of our very busy schedules. I hosted a texas hold em poker party last weekend, which I won 1st place might I add, and the smeel was horrendous!!!! everyone kept asking where the fish was.

After reading this site and realizing the smell is caused by electrical heating, I sniffed all switches, sockets, outlets and breaker boxes. It turned out to be my ceiling fan. Not completly sure its the fan or the actual wiring to the fan as i cant get close enough to be sure. I did turn the light on and after 10 min, stood on a chair and the smell was very concentrated up in the fan. It is located right next to a vent also which explains the scent when it cycles on. we had this light on all night at my party also.

Thanks to all that take the time to be informative to those in need. Without you, my life at home stinks! :)


Jan 09, 2012
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FISHY SMELL
by: Anonymous

I've noticed this fishy scent in one of my bedroom... I've checked in the closet under the bed because I thought that something was dead in the room. My airhandler is in the attic above this room so I thought the odor was coming from that, after having it checked and the coils cleaned I decided to google it after reading about the electrical outlets I started to sniff all that was in the room not only was the scent coming from it but the plug was really hot !!! Thanks for the information.

Jan 02, 2012
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Same smell for a while until now!!!
by: Anonymous

Thanks to this forum i fixed a plug that was not only smelt like a fishing trip but was red hot its been like this for a long time i checked air/heater, attic, under the house i almost started taring my walls out, im a drywaller so no big dill for me:) but i have never heard anything about this on the job for the last 16 years, scarry! people shoyld know about this like they should about fire alarm! Anyways thanks alot and stay safe!

Dec 08, 2011
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Answer to fishy smell in house
by: Nicole from Laton

Well about 10 minutes after I posted the first comment by reading these comments me and my sister decided to check our light fixtures and our sockets...Our light sockets were red hot to the touch in the dining room where the smell was.

Right after we realized that, all the lights in our house turned off, the circuit tripped. So we immediately called the electrician, he came out and changed our 2 light sockets and found the wires inside were burning.

They fell apart as soon as he opened them and took the wires out. As soon as the outlets were changed out the smell was gone....And hasnt came back...So thank you to all on this website for your advice...we tried what you said and saved ourselves from a possible house fire and a horrible stench in our home.

I hope this post is helpful to anybody else who may be having the same problem......Nicole

Dec 07, 2011
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Electrical arc
by: Dadan

If the breaker is causing the fishy smell then by being near a breaker, the smell should intensify.

If the breaker is outside, how is it carries the fishy smell indoor? The situation below seems to cause by electrical arc.

You could check your extension cord. Try Googling electric smell or ozone smell. Is your fishy smell cause by your central air unit?

Dec 06, 2011
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Fishy smell thru house
by: Nicole from laton

We are experiencing the same fishy smell. We have a comp desk in the dining room w a vent directly over it. Weve cleaned the whole area and still nothing. Weve checked the vents in the house and nothing.

My question is if it is the circuit breaker will the breaker box smell? And what if the circuit breaker is outside? Does that have any bearing on the situation. Or is it the wiring in the walls. Anyone who can answer any of my questions it would be greatly appreciated.

For we are at a loss with this situation also. The smell is unbearable and seems to come and go as it pleases. Thank you for any help w this situation...Nicole

Nov 13, 2011
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Fish smell from central ac vent
by: Patrick

For the last two years we have had a fish smell that seemed to be coming from one of two ceiling vents we have in our living room. The smell was most prominent when the central ac unit was on, but on occasion it could be smelled when the system was off.

We had the air ducts cleaned and the entire system checked twice. We were ready to have the wall ripped open and have a new duck installed based on the thought that some form of bacteria was in that particular duct. THEN I CAME ACROSS THIS WEB SITE! I checked electrical outlets and all lamps in the room, for any evidence of burning,or incorrect sized light bulbs being used.

I eventually determined that the smell was coming from a lamp over the piano,adjacent to the vent, after it had been on for at least one hour. The smell traveled up the wall towards the vent. When the AC was on, it would blow the smell outward into the room giving the impression that it was the source of the fish smell.

Nov 06, 2011
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Fishy odor in room
by: Anonymous

We just experienced the same strange fishy smell this weekend. My family was staying in our guest room and they asked me why it smelled fishy in there.

I had no idea what she was talking about. But it did smell terrible!! Then I saw this blog and realized that they were using a nightstand light that I never used.

We smelled the outlet on the wall, no smell. Then we smelled the lamp, and it was so strong it almost knocked me over. We unplugged the lamp and within minutes the smell was gone.

The lamp was really hot too. Thank you this wonderful blog!

Oct 24, 2011
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Upstair Bedroom Smell
by: Anonymous


Everyone have different smelling problem with their central ac unit, so don’t presume your central air is causing by the same thing.

I would start where the smell intensify and go from there. Find out what these two bedrooms have or near that could cause the smell. The smell problem is not likely cause by the air conditioner itself. It has to be external smell influence by the central air.

Read the comment below and trying follow it.

Oct 24, 2011
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SAME PROBLEM, BUT MORE DEFINITIVE
by: Anonymous

We have had the same problem in only 2 of the upstairs bedrooms, and only when we turn the air conditioner on (AND ONLY WHEN THE AIR CONDITIONER HAS NOT BEEN RUNNING FOR AT LEAST A COUPLE OF DAYS).

I think it means that some mold has developed in one of the exit runs from the air conditioning units that are outside. After the air runs for quite some time, the smell is gone and remains gone until the Spring of the following year (or again if we have gone a few days with no air, due to the cooler temperatures during the fall months).

We have a new home, only 6 years old, and we have noticed that several of the GFCIs keep tripping. Now, I also wonder, after reading all the comments, if it could be a wiring problem with the air conditioner (central).

But, if that is the problem, why would it only happen after it's not been running for a while? Please advise.

Aug 25, 2011
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our problem too!
by: Anonymous

We had an almost-new central ac in an attic bedroom that began smelling terrible one day. Thought it was a dead animal. Removed a/c from window, opened box - nothing. No dead animals on roof outside window either.

Called an electrical engineer - he told us it was fungus growing inside and told us how to clean it. We followed his instructions and it seemed clean for about a day when the smell came back. He said to toss it and get a new one.

Couldn't find one that would fit the window, so bought a portable instead and threw the first one out. Portable didn't work well, is super noisy and expensive too. After about 1.5 weeks, same smell returned! I nearly cried.

Brought it to repair center - they said they ran it for half a day with no smell. We tried it again, and smell returned! Realized smell wasn't from a/c but from outlet! Used extension cord to another outlet - no problem! Changed the outlet - it had two loose wires and we thank G-d it didn't cause a fire! Feel really bad about the a/c we threw out, especially since I really don't like the new one.

Aug 11, 2011
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Problem Solved
by: Anonymous

We had the same problem and it turned out to
be the switch for the A.C. It was hot and smelled from fish as it was buring up!! We
replaced the switch and avoided a fire.
So change the switch on the furnace.

Jul 17, 2011
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FISH SMELL
by: Anonymous

I am having the same problem in my home. I just noticed it today. It seems to come from the master's bedroom and stronger when the AC is on. Yes it is very humid here (Hongkong's humidity in the summer is atrocious!). I tried wiping the walls close to where the smell is coming from with bleach/water hoping that it would kill any unseen molds that may be cusing the smell... unsuccessful. I turned off the AC... the smell is not as strong but somehow it lingers but only at a spot where the AC vents were blowing on to. I will get a contractor to come in and check the electrical wiring tomorrow (someone mentioned old wiring and arcing as a possible cause. Will share any outcome. Would appreciate too if anyone has other ideas.

May 20, 2011
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FISH SMELL IN HOME
by: Anonymous

I am having the same problem in my home. We have 3 units. This will be our 8th summer here and we still cannot figure it out. The smell is horrible. It randomly comes and goes. I thought I was on to something when I noticed it seemed to happen after heavy rains. It is terrible now and a storm is forecasted. There is no fuse box near the rooms in question. There are two units directly above these rooms. I am so frustrated! I am going to have an electrician come look at the circuit breakers.

Jul 09, 2010
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Fishy smell
by: Holly Watson

Well, here's the update. The fans seem to have worked in the crawl space, because while they were blowing... no smell. The night they were removed, ...stinksville.

Doesn't seem to have anything to do with my AC at all.

Our builder is going to condition the crawl space (as this is a new home). This should eliminate the random fishy odor and solve the mystery :)

Took us 3 1/2 years to find this answer...hopefully, this is the last of the stink. Whoo Hoo.

Here's to hoping I never have to post another comment about this issue.

Jul 08, 2010
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Mystery Solved!
by: Original Poster

Thanks to everyone for their suggestions. We did solve the mystery. It was melting circuit breakers causing the fish smell. Our fuse box is in the mudroom and the circuit breaker to the a/c as well as the one adjacent to it was all melted. A fire is waiting to happen. We are very lucky we caught it. Apparently, older breakers (our's were about 20 years old we believe) can cause this unusual smell. We changed the breakers and have had an electrician inspect. All is well! Hopefully this may lead to some other people figuring out a potentially very dangerous problem. Who would have thought?

Jul 08, 2010
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Check your flooring
by: Anonymous

Has anything ever been spilled on the flooring?
Has it ever been soaked in the mud room? Has the flooring been replaced since the smell began or just before the smell began?

If you are not the first owner of the home, did it begin since you first lived there or in later years?

Just a thought.

Jun 24, 2010
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To Holly and Long Island
by: Anonymous

Holly and Island

What happen next? I?m flying by the seat of my pants here. I?m curious. I had similar situation.

Thanks in advance

Jun 23, 2010
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fishy smell
by: Holly Watson

We had the environmentl specialst recommend two large powerful fans o help circulate the air in our crawl space. This seems to have worked in another home in our neighborhood. I was told odors like this can rise to present themsleves only in specific areas in the upper levels of a home. Definitely worth a try.

If this does work ... our entire crawl space will need to be sealed off...and made into bascially a heated and cooled (controlled) environment. I'll let you know what happens.



Jun 22, 2010
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Electrical Update from Original Poster
by: Long Island

My husband checked all the circuit breakers and pulled out 2 that were quite burnt/melted looking and smelling somewhat of fish. One went to the a/c, the other adjacent to it goes to our dishwasher.

He replaced them, but we have a call in to the electrician to come by and check out the wiring and whatever else leads off these. The smell seems to have been a blessing in disguise, could have very likely led to an electrical fire.

Not sure if the breakers were just worn and arcing from age (home is 20 years old) or something else created the problem. Still not certain if this was responsible for the smell.

We ran the a/c with the new breakers, but the room smelled so bad from yesterday's run that I'm not sure if it's lingering odor or new from today. Will continue to keep you posted.

Jun 22, 2010
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Fishy smell
by: Holly Watson

Thanks so much for the info...Definitley something the check out. We are having another environmental specialist come to check the crawl space...he says the odor may be coming from there. I'm doubtful as it comes and goes. I'll give him a chance since he's the specialst :)

Please continue to keep me posted on the electrical issues...and possible soutions there. I so appreciate any input.

Holly

Jun 21, 2010
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Possible Answer to Fish Smell
by: Shawn

Hey, Watson

I was referring to Long Island (the original poster).

Electricity arcing produce fish smell?? Hopefully that is the answer.

Long Island, I'm looking forward to hearing from you.

Jun 21, 2010
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Possible Answer to Fish Smell
by: Original Poster

We may have the answer. Our circuit breaker box is also in the fishy smelling mudroom. (reminder-there are no a/c vents in there, but the a/c unit is in the attic above the mudroom, the only room that smells in the house is the mudroom, and only when the a/c is on, exterminator says it is not dead animal, a/c professional says there is nothing wrong with the a/c unit in the attic, and it doesn't smell in the attic by the unit. My husband thinks he should rip out the sheetrock to see what is hiding inthe walls.

I think it has to be tied into the a/c and the wiring. Well, I looked up fish smell and electrical and found several articles saying that electricity arcing (caused by faulty wiring, something electrical gone wrong and burning, can occur in an outlet, etc.) can cause the fish smell.

Tomorrow we plan on replacing the circuit breaker, if that doesn't help we will have an electrician replace more electrical components if needed.

Wish us luck! I'm feeling hopeful that this is it! I hope it may answer some of your questions for those of you with the same mysterious smell. Will keep you posted!

Jun 20, 2010
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fishy smell
by: holly Watson

It's been very hot here to day and again the smell is back at out house tonight. I've turned off the AC. Ugh. It is not a portable unit. We have two AC units to cool the upstairs. Our home is 4700 sqaure feet.. so it requires 3 units. The drain pans are spotless as a side note. My husband was curious that perhaps the wrong size units for the footage upstairs were installed and perhaps that may somehow be putting off the odor. I was told they were the right size,,, but what if they simply aren't? Just a thought. I can say that when there is no smell... the units cool the house very well. I do not like a hot or stuffy home... so down stairs is usually set on 72 and upstairs... 74 cools just fine. In fact is you put either of the units upstairs o 71 or 72... it can get down right cold...

I'm so frustrated. We can replace the coils ...but I have heard that doesn't always help....what about just new units all together? would that fix it? The duct work is clean as can be.

Thoughts?




Jun 19, 2010
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Central Ac Smell Like Fish
by: Shawn

I don't understand this. If it not central air conditioner unit, then why does it smells when you turn the ac on?

Do you have portable air conditioner unit? Could you turn your portable ac in the Mudroom to see if it smells.

I'm trying to understand why does it smells on cold air only and not hot air. The technician said it not central air conditioner unit, then what else could it be.

By the way, if you find solutions to the problem. Come back here and tell us. We really want to know.

Jun 17, 2010
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Fish Smell
by: Holly Watson

Ugh...We have had the same fishy smell in our home too! Never in the winter and randomly...usually in the evening, when the temps get really hot outside. Only upstairs in our home... and only in specific rooms.. not the entire upstairs. We have had a UV light installed, have had the coils cleaned, have had the duct work cleaned (the home is only 3 1/2 years old... so the ducts weren't even dirty). We've had a fan installed in our crawl space to see if that would work. It didn't. It's not the valves in the bathrooms either. This frustrating odor comes and goes...it will cease when we turn off the AC...the problem is... eventually we have to trun it back on.

We've had the gas checked... pest control check everything and an environmental specialist come to our home. The strange thing ...is that it is random, every couple of nights in the summer. If anyone has any suggestions...I would welcome the advice.

Jun 16, 2010
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Central Ac Has Fish Smell
by: Gary

Hey, Long Island

It's good to hear from you. This problem is interesting and I hope you're find the solution for it. I'm looking forward to reading other thought on this matter.

Jun 16, 2010
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Still Fishy!
by: Anonymous

I posted this a few weeks ago and have since had an exterminator confirm it is not a dead animal, and have had an central air conditioner repair man confirm it is not coming from our Ac unit. No smell or leaks in the unit up in the attic over the mudroom. We are completely confused!

The smell only comes when the A/C condenser is on, (not when the fan alone is on) does not permeate through the vents into the rest of the house at all. The smell is just in our mudroom where there are no vents, but the central unit is above in the attic.

My husband is planning on beginning to rip out sheetrock little by little to see whats in the walls that may make the smell. The A/C guy recommended we vent the mudroom to the outside and an additional vent to our garage so there will be circulation of air.

But the smell still comes even when we have the doors totally open. The washer and dryer have been rmoved to see if that was it. They weren't. The drain for the washer has been checked, and that is not the culprit. Vent for dryer is clear as well. Wiring on A/C was checked too.

We scrubbed the walls and floor with bleach, but the fish smell still came when the A/C went back on. We placed a small tub of Clean Air deodorizer in there which has helped, but have not turned the A/C back on since. No idea! Anymore suggestions? We have been avoiding using the A/C to avoid the smell which is now gone...until we turn it back on.

Jun 16, 2010
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Fish Smell Out Of Central Ac Unit
by: Anonymous

I just want to post regarding this issue. For a few summers we have experienced the same issue. We have central heat/air.

During winters, we never have a smell in our house. Every summer, the same smell. Stinks like fish terrible. Permeates in specific spots of the house which are den, living room, and hallway. It is not everyday but often.

We burn candles to override the smell but it is very embarrassing and horrible. Not sure what it could be? Started researching tonight to see if this is common.

May need to call repair man to come over and do some work? As far as tearing out walls in your mudroom, I wouldn't....this is something ongoing for a few years we have experience only with AC on. Any suggestions?

May 27, 2010
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Cold Air Sink And Hot Air Rise
by: Shawn

Basis on the information you provided. We now know the evaporator coil and the central air conditioner unit is not the source of the fish smells.

Is it possible the animal could have died in the attic. And lying on the mudroom cellar. You only have the smell when the central air conditioner is on. The reason I said that is cold air sink and hot air rise. It didn't smell when the heat was on, but why cold air. So that have to be it.

Here a idea.

Is there a way for you guys to spray a perfume above the mudroom cellar in the attic and then turn the central air conditioner on. I want to see if it still produce the fish smells or the perfume.

Your attic is hot, right? I don't know the reaction between hot air and perfume, so don't stay there long.

May 27, 2010
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Still trying to figure out Fish Smell
by: Long Island, NY

Hi Shawn,

Thank you for your suggestions. Here's what we did today to try to figure out the smell in the mudroom when the a/c is turned on.

We taped up all the a/c vents in the den and sealed the door from the den to the mudroom with a plastic drop cloth and tape. We turned the fan on for quite awhile and no smell came into the den. And I don't think the mudroom smelled either, although there was some odor lingering from yesterday (the mudroom has no vents but a trap door to the attic where the a/c unit sits.) We tried our best to seal this trap door too, but I don't think it was air tight. We then turned on the a/c, no smell in the den, but I think the mudroom became smellier. We took the tape off the vents in the den and no smell came in while the a/c was on (the den door to the mudroom was still sealed).

So that's where it stands now. Smell is definitely not coming out of the vents/ducts to the den. Definitely starting in the mudroom where there are no a/c vents, but only starts to smell when the a/c is on.

We are at a loss. Only thing we can still think of is that an animal died in a mudroom wall. But why would it only smell when the a/c comes on? We had a mouse die in our bathroom over the winter and it smelled terribly bad all the time until we figured out what caused it, ripped out the vanity and found the dead mouse, no m ore smell now (the dead mouse made a sewer smell, not like this fishy smell).

Considering ripping out sheetrock in mudroom, but hoping someone has a better idea before we go through all that.

May 26, 2010
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Fish Smell From Central Ac Units
by: Shawn

This is interesting and I read it 7 time. I was thinking the same thing. I thought a animal could have die in the duct works, since that is not the case. Here is my question:

Does it has the smell when you initially turn the central air conditioner on and it die out or the fish smell continence whenever the central ac is On?

What is your environment like? Is it humidity, rain a lot?

Where is the return vent near? Is there 1 or 2 returns vent?

Does the kitchen have it owns supply air vent?

How many central air conditioner do you have? 1 or 2..

On top of your mudroom and den is central air conditioner unit, right? Here what I need you to do.

1. Turn the central air conditioner unit to OFF position and wait for 5 minutes. And then turn the fan from Auto to On. ( The central ac is off, right?)

2. Does it smells?

3. If it does smell. Turn the Fan back to Auto and wait for the smell to dissipate, so you can tell the different.

4. Next block the airflow from the two vent in the den (air tight if possible).

5. After you block the two vent. Turn the fan back to On Position and where is the stronger smell coming from? Which room? Is that room near the central air conditioner units Or far from it.

Here is piece of information. All the room near the central air conditioner unit got the fish smell and all the room far away form the central does not have the smell.

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