HVAC Duct odor diagnosis & cure Questions & Answers:

FAQs help diagnose the cause & suggest the cure for various types of smells traced to air conditioning or heating air ducts, registers, and air handlers.

This article series explains the diagnosis and cure of odors in HVAC ducts, air handlers, blowers, for both warm air heating and air conditioning systems.

Building Air Duct and Air Handler Odor FAQs

These Questions & Answers about How to Find, Test, & Remove Odors, Odor Detection, Smells, & Gases that Appear in Ductwork were posted originally

at ODORS in AIR HANDLERS & DUCT WORK where we list a series of diagnostic articles and steps that help track down, find, and remove the sources of smells or odors blamed on heating or air conditioning or ventilation ducts.

Be sure to review that article.

Our house is leaning and has cracks and smells and we're sick

Our house is leaning and has cracks we are ill including the cats it smells and we get burnt and can't breathe On 2016-11-13 by Sarah Cooke

Warnings by (mod) -

Sarah this doesn't sound like a simple air duct odor since your house is leaning and cracked. You haven't said how much lean, how bad are the cracks, where they are, nor what sort of smell is present. So I can but warn of some obvious possible immediate serious safety hazards:

Watch out: GAS LEAKS: if a building has moved, from settlement, frost heaves, earthquake, etc. enough to damage gas piping there is risk of a gas leak and a fatal fire or gas explosion.

Watch out: Sewer leaks: similarly, a broken sewer pipe risks both health hazards and a methane gas explosion.

Watch out: If there is serious structural damage there is risk of a collapsed building and injuries or worse.

Don't panic, but IF you have reason to suspect ANY unsafe conditions in the home it makes sense to get everyone out and call emergency services from another location. 911.

If there is not a real urgent problem (ok so you actually can breather), then you may benefit by asking for a professional home inspection by building expert to help you sort out what's going on. At the top of this page at the right line of links see EXPERTS DIRECTORY

 

Question: duct odor problems

Hello. i have been having a a strong (to me, anyway - plus i smell it on my clothes when out of the house) tar odor in my house when our AC system runs.

I've had countless HVAC people over, discussed with a former contractor - everyone but one person (more later) pretty much shrugs their shoulders and says, "i don't know."

So - here is some background: we live in chicago in a rowhouse with a 'flat' roof. Our AC unit is a rooftop unit (condensor/fan on roof) and our heating system is from steam boilers - completely separate.

the smell only comes around when we run the house fan or AC.

About five years ago (when i noticed the smell but have since had so much going on and it's only been 1 year that i've been working on this problem) we had some work done to the house.

We did some minor reconfiguration and therefore new duct runs in some rooms on the top floor. They also removed 1 of 2 roof vents (the old school kind) to use one as a dryer vent location.

One person who came to fix our AC unit (which is 15yrs old BTW) actually found a section of the return air duct that had an 8inch round hole in it. Yes - the contractor left it open to the 'attic'. i was hopeful that by sealing that up the smell/issue would be resolved.

No such luck. I'm wondering if there are other deficiencies in the duct work. What other advice or options could you suggest to get to the bottom of this? A home inspector? Where to start - i need something more scientific and targeted!

The HVAC people for the most part just advise me to re-do everything and i really can't afford that.

Or even part of it - but i NEED to figure this out. We have a toddler in the house now and i want a happy, healthy home. i would love some suggestions. thank you for your time. (July 12, 2014) AS

Reply: here is a link to our duct odor and smell diagnostic procedure

AS

It does sound as if there,may be other duct or,return air leaks and contaminants.

Give a call to a large HVAC company, talk with the service manager, and ask for help from a senior, experienced technician.

Keep us posted.

See the diagnostics at ODORS in AIR HANDLERS & DUCT WORK

Question: smell indoors coming from nearby portable generator

I am getting a smell in my rooms that At first I thought was caused by someone running a generator in the neighborhood but it became more often was getting kindoa sick. it smell like a leaky manifold on a car or truck but it's in my house.

Even when I turn all AC and Heater to OFF I get the smell for hours and once in a while it goes away for a few hours. the smell stays even with I have doors and windows open.

I called AC/ Heater tech and he says in 50 years he hadn't heard of my symptoms because the system is off he didn't think it was the heat exchanger since no heat was being used etc

He's coming to look tomorrow. My bedroom is now smelling as I type this - I have to go outside. (May 23, 2014) Dave Wallace s

Reply: if duct odors make you sick, first address immediate life safety concerns

Watch out: in addition to requiring that a portable generator motor not operate where its exhaust enters your building air supply,

Be sure you have a working carbon monoxide and smoke detector installed

Fishy smell coming from the air supply vent in our bathroom

I noticed a fishy smell coming from the vent in my downstairs bathroom.

I called a plumber/electrician and he went into my crawlspace and said there is water in the duct leading to that vent. I asked from where and he said probably someone poured water in the vent because there is so much of it, but I find that unlikely.

What else could cause the water in the vent and is that the source of the smell?? The same company installed a new water heater in my garage 2 weeks ago but assured me this is unrelated. They tell me they need to replace that portion of the duct and install a system to kill germs in the ductwork for $1700. Seeking a second opinion. Thank you. On 2020-05-11 by Diane F

Reply by (mod) - fix the wet crawlspace, check for mold, don't just "spray and forget"

Diane:

Before proceeding with a cleaning and repair we need to find where the water or leak originated - else there's not much gain in "fixing" anything as the problem can just recur.

I can't see enough about the construction of your home to follow the water back to its source, but that's what I'd ask your inspector to do.

I agree that if fiberglass type HVAC ducts or other fiberglass insulation have been wet it's appropriate to replace them.

I'm unclear about why you need a "germ killer" and less clear about what would be effective. Ask why? And get the specifics on "what" would be installed.

How do I stop Food cooking odour coming through all the return air vents in my hous

Hi, please help me to find how to fix this!

Food cooking odour coming through all the return air vents in my house.

The house is from 2012, two storey house.

I always noticed food odour in the second floor after cooking but I always thing that was the air traveling through the stairs until now. I just noticed a month ago, the smell of cooking food coming through the return vents when I was changing my baby in her bedroom while my husband was cooking the breakfast.

The exhaust microwave fan was on. I ran to the other return air vents and noticed the smell coming though. I just realized that I never noticed before because I was always in the kitchen when I was cooking.

I dont understand why is coming air and smell from the microwave fan when we are cooking.

I dont know how to fix this, I suppose this isn’t normal?

Air coming through a return vent?
Please, help me
Thank you On 2020-01-31 by Olga

Old rotten cabbage smell coming thru my mother's AC vents

My mother has a old rotten cabbage smell coming thru her AC vents in her home. The house was built in the 70s and she has never experienced this smell in her home before just as of recently. Not for sure what the issue is and my mother is elderly wit hhealth issues.

Not for sure if this smell is going to be more of an issue for her or not. Do you have any suggestions or solutions? Thanks On 2017-06-19 by Anonymous -

Reply by (mod) -

Olga

Air does not normally come OUT of return vents - it goes IN, through the air handler, through the heating or cooling equipment, then is pushed by the blower fan out at the air supply registers.

If you have air coming out of return vents somethng's wrong with your duct system and

we need an onsite HVAC tech to take a look at the ductwork and at the blower fan (is it running backwards?)

Let's straighten out this question first.

Anon: start with your mom's doctor to be sure to rule out any neurological or health complaint.

Then inspect the building for an odor source including poor housekeeping, trash, spills, or area where there may have been leaks and mold contamination (a health concern if present.)

Followup by Olga

Thank you for your response
Yes, the air in coming out of the return vent, I know it is really strange, I don’t know why?

Definitely, we need to ask to some hvac tech to come and see what is happening
Thank you

Advice by (mod) - check blower fan direction

Olga

If the blower fan is OFF completely, do you still have air coming out of a return vent? If so then maybe there's wind blowing into the duct system somehwere. OR the blower fan is installed backwards, blowing in the wrong direction.

Ask your heating service tech to check the fan rotation direction. I've seen this problem when a blower fan was removed for cleaning and then on replacement was installed backwards.

How do we cure a smell of dust odor in the air when our furnace runs?

I have allergies. Had the ducts cleaned. But with the furnace on something is going through the air. Had filters put on the returns. Doesn't help or show dust.

Put two air purifiers in basement. Have a 1915 house. Very frustrating been chasing this for 2 years. There is asbestos in the basement, but can't smell that because it's odorless. What am I smelling. My mouth feels like dust and peebles and it stuffs my nose. Please help. Thank you

The smell is a fine dust that just goes through the air when the furnace is on. The duct guy said everything is clean. He put a filter outside one supply duct and it looks clean too. I have spent much money chasing this problem.

The duct guy wants to seal the system--furnace but don't think my wife will want me to spend more money.

Extremely frustrating. I put a air purifier inside the furnace by the blower fan and that's not helping either. Do you have any other suggestions.

Could carbon monoxide becoming in play here. How can I actually find the irriating particulars. Thank you so much. On 2019-12-11 by Paul Delger H

On 2019-12-11 by (mod) -

Paul

Watch out: be sure you have working, properly-located CO detectors in the home; CO poisoning can be fatal.

CO carbon monoxide itself is odorless and colorless. However CO leaked from a heating system will usually be mixed with other flue gases and might have an odor - depending on the fuel type being burned - of gases or heating oil.

Paul

Besides having ducts cleaned, it is often important to clean the air handler itself, the supply and return plenums and the actual blades of the blower fan.

Beyond cleaning that air handling system you want to find the odor source as it is often being picked up in return air and re-distributed in the building.

The best approach is to find and remove the source of allergens; otherwise what we have, in effect, is an infinite source or problem particles that we are trying to remove from indoor air after the fact. (Asbestos won't trigger allergies and is safest left un-disturbed).

"Air purifiers" cannot purify air any more than waving a vacuum cleaner wand in the air while standing in the kitchen will suck the dust bunnies from under the couch.

I can't know what you're smelling, but sometimes you can enlist the help of an independent person who has a good sense of smell and make use of a

simple SMELL PATCH TEST to FIND ODOR SOURCEto find an odor source by testing different building surfaces & materials.

The difficulty in "finding the irritating particles" is that in my opinion we do not want to hire an expensive consultant who stops by to collect some sort of generic sample, send that to a lab, and have the report sent to you. Such shooting in the dark is costly and rarely hits a useful target.

However you could try collecting particles from the surface of one of your air filters, using clear adhesive tape, and having that analyzed by a forensic lab to see if there are abnormal levels of any particular particle type.

See details at

DUST SAMPLING PROCEDURE

and

TAPE & BULK SAMPLING & TESTS for MOLD or DUST

Identifying what's in the dust - particle identification - can help identify its exact source and thus suggest what cleaning, filtering, or other steps are needed.

by Paul Delger

The smell I smell is dust. Could it be coming from the attic. The filters seem to be pretty clean

by (mod) -

Within limits (as too much filtration will slow air flow) you can add HEPA or other filtration;

But most effective is to find and clean up, remove, or seal off sources of irritating particles or odors.

Sewage and trash found in our heater air register (vent)

I opened heater vent in kitchen an found 10 gals of smelly sewer water included peices of tissue an a cigarette butt. On 2019-10-08 by LINDA Parker

Warning by (mod) -

Linda

Watch out: sewage in buildings is a serious health hazard.

It sounds as if there is a sewer line that is broken and leaking into your heating ductwork. You'll need help from a plumber to find and fix the leak and then you'll need to replace any ductwork that cannot be cleaned and disinfected thoroughly.

Most likely you need help from a professional cleaning service who know how to disinfect the affected building ductwork and other areas.

Noxious odor from our new Goodman furnace

New Goodman furnace emits noxious odor through air vents. Now that odor continues to be emitted even if the heat pump runs instead. Never smelled anything like it. It gets in my sinuses and in my throat and makes me gag.

I used a charcoal filter and it worked somewhat for about 30 hours then the smell was back.

I fear it is killing me and my dog. New heat pump. New gas furnace. All new ductwork. On 2019-02-14 by Donna

Reply by mod:

Watch out: first be sure that you have working carbon monoxide and smoke detectors properly installed, located, and tested.

Watch out: be sure that there are no gas leaks such as from an LP gas or natural gas supply - an immediate risk of fire or explosion.

With those critical safety concerns addressed, check with your installer; often new heating equipment produces an odor from oils in the air handler; those should "burn off" in a day or two; If not there may be a more-serious hazard.

See our diagnostic advice at HVAC SYSTEM ODORS 

Where to find the source of odor from our heating and cooling system in our manufactured home?

We live in a manufactured double wide home with a crawl space.We have a horrible odor coming from the heating and cooling system.We have had several opinions of the smell, dead animal, sewer, etc.

We get this horrible smell only when the heating or air conditioning is operating and the temperature is 80 degrees or above On 2018-11-11 by Sam

Suggestions by (mod) -

A good place to start tracking down air conditioning or duct odors is with the list of common odor sources in the article above on this page.

Pay particular attention to any possible odor sources including a dead animal that's near the return air Inlet. Of course you want to inspect the duct system from underneath the home to look for openings.

If none of that reveals an obvious odor Source then it would be appropriate to have the duct interior inspected with a camera system. Let me know what you're told and I may be able to offer more suggestions.

Pungent odor coming from our air conditioning vents in South Florida

Re-posting from private email:

I am hoping that you may be able to help me with a concern if mine. I recently moved to South Florida to attend school and am renting an apartment.

I noticed a pungent smell coming from my vents and decided to try and clean them myself since the building manager did not respond to my maintenance request.

What I found is disturbing to say the least.

Could you help me identify what is going on inside my air vents? I'm not sure what they are made of or if that is mold you see in the photos.

Any advice is much appreciated as the building manager hasn't been much help at all and as a student, I cannot afford to pay somebody to check it right now.

I've been sick a lot lately and now think my air quality could be to blame. Thank you in advance for reading this. If you'd like to use the photos as examples to inform others that would be great of you. - Anonymous, Florida. On 2018-11-10 by Anon

Here is an Additional photo that looks like white sealant superficially sprayed into the HVAC duct.

A useful diagnostic thought: if you definitely feel better after spending time out of the building that can indeed suggest that the building contributes to or possibly even causes the complaint. This isn't 100% but it's a useful consideration.

(Photos lost by Comment box code support error - sorry, Mod)

Moderator reply:

The HVAC air ducts in your photos are made of a fiberglass material whose surface is somewhat rough. It is normal for dust and debris to stick to the surface to a degree and normally that's not harmful (house dust is principally skin cells and fabric fibers).

However if water has gotten into the duct system from leaks or from mis-handling of condensate near the air handler, that water or moisture can stimulate mold growth (on the organic materials deposited in the ducts).

Some of the white in the photos looks as if someone sprayed paint or a sealant that partially-covered some surfaces. That MIGHT be an indicator that there was a prior concern about duct surface contamination AND that an incompetent effort was made to address it - incompetent because partial spraying of a sealant is ineffective.

Still I can't see anything definitive in your photos that would be identified as an odor source. And an odor could be coming from another building location and could be transported by the duct system.

Watch out: do not try mechanically cleaning fiberglass ductwork; it's not possible, and doing so disturbs the integrity of the duct surface, damaging it and increasing future problems with fiberglass release into the air as well as in collecting dirt and debris.

Take a look at ODOR DIAGNOSIS SIX STEPS and the articles in that series.

Foot and fecal smell from the air conditioner

our building has a fecal/smelly foot odor when ever the ac is turned on . any thoughts on what it could be? On 2017-04-12 by teacher

by (mod) - inspect the air handler and ductwork for having been or still being wet

T

I would inspect the air handler and ductwork for having been or still being wet; those conditions can produce mold growth that smells.

I would also double check that there are no sewer line leaks that leaked into the ductwork as I've on occasion found in basements and crawl areas.

I would check the location of the return air inlets to see if the system is pulling air from a smelly floor drain, plumbing fixture, dry plumbing trap.

Finally, if this is a new problem I would ask what has changed as that can give clues about where to look further.

Could a dead animal be making our ductwork smell?

We bought our house a year ago and we have noticed that occasionally we get a fowl smell down our hall and in a certain area of the house..

Upstairs only, never in the basement.. It seems to run along the main duct for air conditioning and heating.. It smells fishy (stinks pretty bad)..

We had our septic tank pumped thinking it was that and it wasn't. We have run water in the bathroom tubs that don't get used much to see if that was it and it still happens. Could it be something in the duct and if so what? On 2016-07-22 by Kristi

by (mod) -

Yes there could be a dead animal in the ductwork; why not ask for an inspection (perhaps by camera) of the duct system?

How to get rid of Old building smell in Houston home

We moved into 30 Yr old house in Houston and it has this peculiar smell on second floor(mostly) but very little hint on first floor too. We though it was carpet and got it replaced, smell reduced but it is still there.

The smell get stronger with increase in temperature, at temperature below 73 it is not noticeable much but the harmful effect is still there, the smell also get stronger if I close the Rooms door, it seems with no circulation the intensity get stronger at same temperature. I have changed all filters and it did not help.

Called the carpet guy and he says it is old building smell and not mold smell ..I am out of ideas . Help! On 2016-07-19 by Ray

by (mod) -

"Old building smell" is a familiar but troubling term; the smell comes from something besides mere age.

I suggest searching InspectApedia for SMELL PATCH TEST KIT to read a simple procedure for narrowing down the probable odor source in the smelly room.

by Ray

Thanks for reply, I will run the patch test but smell is not confined in single room, I smell it at stairs (2 intake vents closeby), restroom, 2 rooms on other side of stairs ..

These are all on second floor. Very less (<5% smell in few specific areas on first floor) like kitchen nook- on opposite side of stairs and there is no smell in kitchen that is in between or in any other area on first floor.
if i want to call someone to test who would be the right people ?

by (mod) -

Ray it's an economical approach that is worth trying.
If you call an industrial hygienist be sure that the person has experience with this specific sort of issue. Otherwise you risk hiring an expensive consultant who does little that's useful.

Metallic smell from air ducts when A/C is on

When I use my AC system I get a 'metallic' smell in the house coming from the ducts.

This is a combination heating / cooling unit and I don't get the smell in the winter when the heater is working. That tells me the smell is being masked / eliminated by the heat, or the AC system itself is causing the smell.

I've had two different HVAC contractors out for other reasons and they can't identify the smell. Any idea what might be causing it? On 2016-06-17 by Terry

by (mod) -

Terry, refrigerant itself is odorless; oils or spills into the air handler or duct system as well as odor sources near the air return inlets often track down the source of an odor.

Identifying a smell by its odor is a useful step in diagnosing the trouble but it's no surprise that that's not enough or that it leaves everyone uncertain.

A visual inspection for leaks and spills, for overheating electrical components, and for leaks anywhere in the return ducting may help find the trouble. Keep me posted.

by Terry

Thank you for that information. There is no odor near the air return inlets. The smell started shortly after we had the supply ducts replaced. Confusing to me is that I can smell it when the AC is running but not the heat. Maybe the heat is masking / destroying the smell?

I have a flat roof (live in the desert SW) and this system is mounted on my roof, the AC unit and all the ducts which penetrate the roof directly to the supply registers. I would hope my system is well enough sealed that it would not pull air in from the outside but I suppose that is possible. Even so, I don't ever smell that metallic type of smell when I'm on the roof.

I'm familiar with electrical smell (overheating, burned wires, etc.) and this is nothing like that.

Any suggestions on a deodorizer I could atomize in the returns to see if I could mask it or maybe eliminate it if it is something organic?

by (mod) -

I'd look for a condensate system leak or a spill in the air handler or ductwork.

by Terry

great suggestions - thanks, will look for those and let you know what I find!

Question: new plastic odor from vents

I have a smell coming from the air conditioning vents. It smells like new plastic. What could be causing it? July 9, 2014) Kay

Reply:

Kay

Possibly a burning electrical motor, wire, wire insulation, or an odor being picked up at an air return and transported through the building.

 

Question: stale odors from ductwork

I have a stale smell coming through the duct work when the heat goes on? what could be causing that? (Nov 12, 2014) fruce bagheri

Reply:

Check for leaks into the duct system or dirty ducts that need cleaning.

 

Question: Foul urine odor from ductwork

There is a oul urine odor coming from our ductwork

Reply:

Look for animal urine near an air return or look for mice or other rodent invasion of the ductwork.

Watch out: for bacterial or viral hazards from mice or other animals in the HVAC system

 

Question: intermittent dry ice odor from ceiling vents when heat is on

I have an intermittent stale dry ice odor coming from ceiling vents during heat cycle only, not ac. Outside temps have been between 40s & 60s. Not sure if defrost cycle has ever kicked in, or aux heat. Unit is 8 mo old. Any thoughts anyone? 12/28/2014 Anonymous said

Reply:

I'm not sure what dry ice odors means - dry ice is frozen carbon dioxide or CO2 which is odorless. I'd give the HVAC service company a call to ask for assistance.

 

Question: Odors in Texas duct work

I live in Texas and we've had a couple of weeks of cool weather that required us to use the heater. It warmed up and we turned on the a/c and a foul smell came from the vents. It smelled like something had died. Heat is back on, no smells. What could be causing this problem wit a/c and how do we fix it? (Jan 25, 2015) Jay

Reply:

Jay,

Since we can assume that the same air handler and duct system were in use for heating as for cooling, I'd start by looking right in the air handler for a problem in the heating unit.

 

Question: sewage odors from ducts

why at different times a sewerage smell comes out of our air vents downstairs and not upstairs (Apr 12, 2015) Anonymous said:

Reply:

Perhaps that's where the dry plumbing traps are located.

 

Question: old ductwork, plastic musty smell

I have remove some of the old section of 6 inch duct work and replaced it with flex duct and we have been getting a plastic -musty smell in one of the rooms . What might that be ?(Oct 17, 2015) jeff

Reply:

dirty ducts, leaks into ductwork, spills or leaks in the ceiling, spills or leaks near an air return, open return ducts in the attic

 

Question: Odor coming out of Trane XL20i HVAC system - acrid, burns the throat

Since July we have had an odor coming from our

HVAC...it is a Trane XL20i and it is
pretty bad..it is either an oily smell
like today or acrid where it burns my throat at night.
Our smell is pretty much in our living room...master bedroom
and a couple of days ago in our family room.
Our home is one level with an unfinished basement. (Oct 22, 2015) joyce

Reply:

Joyce:

Inspect the air handler - blower - first for a leak or motor or electrical problem, all of which are unsafe;
IF the ducts and air handler are themselves clean then I'd look fdor an odor source close to the air returns for the system

 

Question: bad smell from wood heater when runs hot

I get a bad smell only from my wood heater, only when it runs hot but not from my propane (Oct 24, 2015) wayne

Reply:

Watch out: I would start with a chimney inspection by a pro: for possible creosote hazards - watch out you could be at risk of a house fire.

Also have a check for gas leaks related to heating piping or controls or connections. also unsafe with obvious fire and explosion risks.

 

Question: sulfur rotten egg smell from AC vents

I have a question. I have a restaurant and suddenly we started getting sulfur or rotten egg like smell from our AC vents. We thought it was coming from the AC unit and had the vents and duct cleaned but the smell is still there. Surprisingly, we have air vent in our restroom and it is not connected to air vents or ducts. The smell is coming through the air vent in the restroom and we don't know and cannot find where it is coming from. Any ideas please help. (Oct 31, 2015) amaraa

Reply:

Amaraa

Refrigerant itself is odorless; so I figure there is an odor source that's being picked up and distributed through the vents: look for a backing up sewer line or drain opening close to a return air source in the system; if you can't find a likely culprit it might be that there's a dead animal in the ductwork.

 

Question: acrid exhaust like smell coming out of our vents from our Trane xl20i HVAC unit.

Since June we have had a kind of acrid exhaust like smell coming out of our vents from our Trane xl20i HVAC unit.
We have had our unit serviced and our air ducts clenaed but we still have that small. I thought it was strictly
just an AC problem but in November we still have it.

I am wondering why it won't go away. We haven't used our fireplace in many years so I don'
think that could be it.

Anyone have any ideas
PS our house is a one story with an unfinished basement.

Our air ducts were cleaned on Thursday and the smell came back today (Sunday). (Nov 15, 2015) joyce

Reply:

That suggests that if the ducts were really thoroughly cleaned (and are not fiberglass lined inside) - all ducts and all of the air handler - then the problem is not in the ductwork but rather is being picked up as an odor entering the return duct system.

 

Question: metallic smell from HVAC ducts

When I use my AC system I get a 'metallic' smell in the house coming from the ducts. This is a combination heating / cooling unit and I don't get the smell in the winter when the heater is working. That tells me the smell is being masked / eliminated by the heat, or the AC system itself is causing the smell.

I've had two different HVAC contractors out for other reasons and they can't identify the smell. Any idea what might be causing it? 2016/06/16 Terry

Reply:

Terry,

HVAC refrigerant itself is odorless; oils or spills into the air handler or duct system as well as odor sources near the air return inlets often track down the source of an odor. Identifying a smell by its odor is a useful step in diagnosing the trouble but it's no surprise that that's not enough or that it leaves everyone uncertain. A visual inspection for leaks and spills, for overheating electrical components, and for leaks anywhere in the return ducting may help find the trouble. Keep me posted.

...

Continue reading at ODORS in AIR HANDLERS & DUCT WORK - topic home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• DUCT SYSTEM DESIGN SIZE & DEFECTS - home
• ODORS GASES SMELLS, DIAGNOSIS & CURE - home
• ODORS in AIR HANDLERS & DUCT WORK
• SMELL PATCH TEST to FIND ODOR SOURCE
• SLAB DUCTWORK to track down and fix leaks, odors, mold, health hazards from in-slab ductwork

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