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6 Toxic Air Conditioning Smells and What They Mean

Air Conditioning, air conditioner smells, air conditioner smells like paint thinner

What’s that awful smell? When your central air conditioner smells bad, it’s never a good sign, and definitely not good for your health. Even worse, some smells are toxic, and require urgent attention.

The air conditioning unit in your home is one of the most-used appliances, and it’s inconvenient and uncomfortable when it isn’t working properly. Fortunately, it’s pretty good about giving signs when it is in need of service. One of the key things that many homeowners notice is bad aromas coming from the unit. An odor problem doesn’t necessarily mean that the repair will be expensive. It could be a dirty air filter or condensation which has created mold in the unit.

Potentially toxic smells coming from your air conditioning unit include…

1.   Burning/Electrical Odors

Electrical odors could indicate a mechanical problem with your AC fan or compressor, wiring issues, or electrical component failure. Made with a variety of metals and chemicals, prolonged exposure to these fumes is not healthy. The first few times the unit kicks on, it may emit a burning odor that can smell electrical and dusty, give it 20 to 30 minutes and see if the smell dissipates. If it does, it probably was just the dust burning off. If it continues, contact a professional HVAC technician to check out the problem and make repairs. An electrical odor typically is a problem within the motor or the wiring. Attempting to fix either of these items can result in severe injuries.

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  2. Gunpowder Smell 

Cousin to ‘burning smells,’ a distinctive, gunpowder-like aroma may also be due to a fried circuit board or fan motor.  With such smells posing similar dangers, it’s always a good idea to call for a professional inspection before running your system again.

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3. Rotten Eggs

Provided there aren’t any rotten eggs in your home, the air conditioner smells of rotten eggs or sulfur most likely indicates a natural gas leak.  Although on its own, natural gas is odorless, most utility providers add the aroma to alert people of a dangerous leak. Don’t take this lightly. If you smell a rotten-egg-like odor in your home, natural gas is likely the culprit, and immediate inspection is a must. While low level exposure is not hazardous to your health, high levels reduce oxygen in the blood, and can lead to loss of consciousness and death. Gas is also highly flammable and explosive, resulting in dozens of deaths each year. If you notice this smell, open the windows to your home right away, get out of the house immediately, then call the gas company.

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4. Exhaust Fumes

Even in systems not powered by gas, exhaust fumes can still result if fluids leak from essential components. To avoid a dangerous situation, have your system professionally assessed. Burning oil and other fluids can release large amounts of toxic gases, different in chemical makeup than in natural, liquid form. These particulates can be hazardous to your health, depleting oxygen and resulting in an array of health issues.

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5. Chemical Aroma

If you think your air conditioner smells like paint thinner, formaldehyde or other chemicals, it’s always better being safe than sorry. Many fluids are used within your air conditioning system that could result in an assortment of chemical odors with system malfunction, making prompt AC repair advisable.

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6.   Musty or Moldy Smell

An air conditioner smells like mildew or mold is probably the most common symptom of central HVAC systems. When the air conditioning is running, there is a lot of condensation within the unit. When the moisture doesn’t drain properly, it can escape into the ducts and create mold. Finding where the mold buildup is and getting it cleaned up will solve the problem. An HVAC repair technician has the knowledge to handle the problem and ensure that it doesn’t occur again.  Note: Mold and mildew smells are not serious problems with the unit, but the poor air quality does increase the risk of respiratory infections in both children and adults. You can still use the unit while you’re waiting for repairs, but you shouldn’t put it off for the sake of your family’s health.

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When troubleshooting the smell, use your other senses as well. Listen for clunking or knocking. Look for excess water on the ground or other liquids which don’t belong. Many times, the smells are not dangerous, just indicative that your system needs service. However, some smells, like rotten eggs or gas are more serious. If you are experiencing an electrical, burning odor, or gas smell, turn off the unit and call your HVAC technician right away. An HVAC repair technician can diagnose the problem and recommend solutions.

Have your central HVAC system inspected annually by Miller’s Heating & Air to look for faulty wiring, loose or worn belts, and general wear on the unit. By having an annual service, you have peace of mind that you’ve done what you can to make sure your central HVAC unit is ready for the seasons ahead.

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— 23 Comments —

  • Jen We have a portable air conditioner until 12 BTU when it’s on it draws the smell of creditor in the house.. we have a wood forced air furnace. How ca we solve the problem Many thanks Jen Reply
    • Ashley Adams Hi Jen, Please call us at 360-695-6500 so one of our dispatchers can help. Best, Miller’s Heating & Air Reply
  • Dee Dennis My window A/C unit smells like the inside of my freezer. Is it the Freon?? Reply
    • Ashley Adams Hi Dee, Please call us at 360-695-6500 so one of our dispatchers can help. Best, Miller's Heating & Air Reply
  • Mary I have an odor in my home that smells like sulfur and sometimes the odor is like a ginger with onion smell, cause at times it causes my eyes to burn, occasionally nose runs a little, it also makes me cough every now and then. The smell gets really bad when I run my hvac. It's a central unit. Some when I run my hot water seems like it's coming through my drains,had my water company to check things out it's not the problem. Reply
    • Ashley Adams Hi Mary, Please call us at 360-695-6500 so one of our dispatchers can help. Best, Miller’s Heating & Air Reply
    • Ashley Adams Please call us at 360-695-6500 so one of our dispatchers can help. Best, Miller’s Heating & Air Reply
  • Mick Musty heat smell from ac unit an Ahri unit rap 13 Reply
    • Ashley Adams Hi Mick, Please call us at 360-695-6500 so one of our dispatchers can help. Best, Miller’s Heating & Air Reply
  • Lisa Why does my window air conditioner smell like gas?? Reply
    • Ashley Adams Please call us at 360-695-6500 so one of our dispatchers can help. Best, Miller’s Heating & Air Reply
    • Marie Dillon My ac smelt like a gassy smell chemical of some sort i called matenace and told them i was smelling something... He said nothing he can do tonight just shut it off, Be there by 8am. i felt kinda disoriented..my friend shared this ad to me and it helped me feel so much better you really have the answers and i thank you so much !! Marie Dillon youngstown ohio..... T Y. Reply
  • Shelly Coleman My home smells like a car or vehicle with a really bad exhaust leak. Its really strong like oil or fuel burning thru an exhaust leak on a vehicle. What could it be?? Reply
    • Ashley Adams Hi Shelly, We only work on residential heating and cooling systems so unfortunately we won't be able to help. It does sound like you should get it checked out by an automotive professional. Reply
  • Lukie After a new furnace an air conditioner install my house smells like moth balls! Reply
    • Ashley Adams Please call us at 360-695-6500 so one of our dispatchers can help. Best, Miller’s Heating & Air Reply
    • Sandy May Yes..mine is smelling like mothballs as well. What is that? Reply
  • Benjamin Hello, For well over (3) months, there has been a foul odor ( I would describe as a dead animal) coming from my bedroom AC vent. It was strongest (3) mos ago, for the first (2) days it was unbearable. The latter few mos, it would come and go. I have removed the vent and inspected for animals but found nothing? Oddly, even at its strongest, it is unnoticeable once the AC is running? Any suggestions? Thanks Reply
    • Ashley Adams Please call us at 360-695-6500 so one of our dispatchers can help. Best, Miller’s Heating & Air Reply
  • Kim Small Hi There is a odor coming from my Air Conditioner Unit, that smells like musty or someone’s butt that hasn’t washed! I have been smelling it for at least a week or more! I am a asthmatic it causes me to cough and I feel nauseous at times. How do I solve this problem! Upon turning it off I looked inside I do see mold spots. Reply
    • Ashley Adams Hi Kim, Please call us at 360-695-6500 so one of our dispatchers can help. Best, Miller’s Heating & Air Reply
  • Violet There is like a rubber smell or electrical coming from the vent. Was checked and nothing was found Reply
    • Ashley Adams Hi Violet, Please call us at 360-695-6500 so one of our dispatchers can help. Best, Miller’s Heating & Air Reply

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