Fish Smell Coming from Central Air Conditioner

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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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Fish Smell Coming from Central Air Conditioner

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Jan 27, 2012
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Fishy Smell in our house (comes and goes) NEW
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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Fish Smell Coming from Central Air Conditioner

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Fish Smell Coming from Central Air Conditioner