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6 Common Heat Pump Smells Explained

By Aztil –

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  • It is not normal for a home to have weird smells, especially when it has air conditioning and heating. An offensive odor that you can smell throughout the house is a sign of trouble. The good news is that these odors are quite distinctive, and so the cause behind them is relatively easy to identify. Usually, most odors will have a link with one heat pump problem or the other. The sooner you identify them and take corrective action, the lesser the chances of any disruption in your comfort. To make things easy for our clients and readers, here is a list of standard heat pump smells and their causes explained.

    Six Common Heat Pump Smells Explained

    1. Musty Or Stale Odor – When you enter a home or building that has been closed for a long time, the indoor air smells off. The best way to describe it is like that of stuffy and old air or the smell of dirty socks. The reason for this smell is mold and mildew that grow in the damp areas of the home. The most conducive environment for their growth and propagation is found in the heat pump near the evaporator coils. From here, the smell is picked up by the circulating air and dispersed throughout the house, making it stinky. 

     How To Get Rid Of It – Staying on top of the annual maintenance routine is the best way to remove the musty odor. During maintenance, the inside of the heat pump is cleaned thoroughly, which removes all mold and fungus. Once they are clean, there is no reason for the stale smell.

    2. Rotten Fish Smell – The smell of rotten fish is hard to ignore. It is so repulsive that staying indoors becomes an ordeal. Your heat pump will emanate this strong and vile odor when some component (plastic or metallic) starts overheating. Before doing anything else, switch off the heat pump to prevent further damage to the unit. Some of the reasons behind the smell could be:

    1. Problems with heat pump wiring.
    2. Overheating of plastic components or melting of rubber coating.
    3. Mechanical issues.
    4. An overheating motor.

    How To Get Rid Of It – Getting rid of the rotten fish smell is a matter of expert handling. You need an HVAC technician to eliminate this heat pump smell as it involves opening the heat pump and checking its internal parts.

    3. Rotten Egg Smells – Rotten egg smell is like the smell of sulfur. Such a smell comes from the heat pump if there is a dead animal or critter inside the ducts. Often, small animals find their way inside the ducts for warmth and protection and die inside. As their body starts rotting, it releases the offensive smell of decomposition. 

     How To Get Rid Of It – To get rid of the rotten egg smell, call your local HVAC technician. He will clean the heat pump and the ducts, if necessary. Once the body of the dead critter is removed, the smell goes away on its own.

    4. Burning Rubber Or Plastic Smell – If it smells like something is burning, it most probably is. Never ignore such smells. Often an electrical problem inside the heat pump will result in wires burning. Essentially, it is the rubber tube on the wires and the surrounding plastic that starts burning. If you fail to recognize this type of odor, the chances are your heat pump will develop a serious issue and stop working altogether. The other probability, if you are lucky, is that the circuit breaker will trip to prevent further damage.

    How To Get Rid Of It – Only an HVAC technician can help you tackle this problem. He will have to open the heat pump to determine where the electrical problem exists and take remedial action.

    5. Heat Pump Smells Like Sewer – If your heat pump produces a sewer-like smell, do remember, there is a high possibility that the circulating air has picked up the smell from elsewhere. The odor does not always initiate in the heat pump. A sewer-like smell means that somewhere in the house, the sewer line is backed up or broken.

    How To Get Rid Of It – You can eliminate the sewer smell only by clearing the backed-up line or fixing the broken pipe. However, this task can only be completed by the company that deals with sewer lines in your locality.

    6. Burning Dust Smell – A heat pump, like any other heating and cooling system, accumulates dust. Switching it on after a long interval results in a strong burning odor that typically goes away on its own within 5 or 10 minutes.

    How To Get Rid Of It – One way of ensuring that this type of odor does not come at all is by ensuring timely maintenance of the heat pump. If, for some reason, that’s not possible, at least clean the unit thoroughly. Else, allow the unit to run for, say, 10 to 15 minutes, and that should be enough time for the odor to go away. If not, call your trusted HVAC technician.

    Takeaway

    The heat pump is not designed to produce any smells. These are actually indicators of what is happening within the heating and cooling system. Hence, it is necessary to be a little vigilant. Thankfully, most heat pump smells are not a thing of grave concern. Yes, they are disgusting and repulsive and make staying indoors an ordeal, but they don’t spell trouble for the system. The same cannot be said for the burning smells. Our only advice is to let your HVAC technician know of the odors as soon as they originate. They shall take care of the rest.

    Aztil Air Conditioningcan help the residents of South Florida find the reason behind their heat pump smells. Our trained, certified, and experienced technicians will thereafter undertake corrective measures to remove them, so you no longer have to suffer unnecessarily. You can also engage our services for HVAC installations , repairs, and maintenance. We also provide 24/7 emergency services . To book an appointment, call +561-559-2205 .

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Niko Garza completed a detailed diagnostic & flush of my home AC. Very professional and courteous. I highly recommend Aztil & Niko
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I wanted to commend Dana Dussualt for his hard work at rectifying a substantial issue that I had with my HVAC system. It did require multiple visits but he stuck with it and figured out the issue and did get it resolved. Dana spent hours in the attic in the middle of summer working on getting this fixed. He is both a very hard worker and a pleasant individual. Dana is a credit to your company. In addition, the office staff worked with me in getting these repairs done by insuring we would get service on the date promised. Having no air conditioning in the summer is not a great experience. I have been an Aztil customer for many years.
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Lazaro is an excellent Tech. Courteous and Professional. If possible ask for him for all your HVAC issues.
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Jorge and Dave we’re extremely professional. The AC installation was done quickly and meticulously. I can’t recommend them enough!

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I scheduled a routine check-up. Aztil canceled on me and the next appointment was 3 weeks later, so I was not happy about that. However, when my technician Ramon showed up, he was very thorough and efficient. He explained what he was doing and made good suggestions to maintain my AC. I was very happy with his work.
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Response from the owner:Dear Cheryl Feldman, thank you for taking the time to share your positive experience with Dana. We're delighted to hear that he provided courteous and knowledgeable service while fixing the problem efficiently. Your satisfaction is our top priority, and we appreciate your five-star rating. If you need any further assistance, please don't hesitate to reach out.
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Ramon Serpa is the best! He performed the maintenance check on my A/C and when I told him about my husband’s allergy problems, he suggested UV lights which would improve the air quality. He installed these for me explaining the process in detail. He is the best technician we have ever had with Aztil.
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I've been using Aztil for over 20 years across 4 homes in Florida. From general services to complete A/C replacements, I wouldn't trust anyone else. My recent service in Port St. Lucie with Nico was excellent and he was very helpful in going over all of my HVAC system and answered a few questions I had.
I highly recommend Aztil for any HVAC issues or general maintenance.
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I cannot speak highly enough of our super kind technician, Randy, who came out to assess our AC today. Randy took the time to walk us through photos of the issues in our AC and offered to take care of it ASAP as he already had the parts in his truck - LOVE the preparedness! Aztil Air Conditioning is superior and we will request Randy on a go forward basis.

UPDATE 6/17/25 - Exceptional Service from True Professionals - Highly Recommend!

We recently had our ducts cleaned and sealed, plus our dryer vent serviced by Jordan and Hero from Aztil Air Conditioning, and I cannot say enough good things about their work. From the moment they arrived, these two demonstrated exactly what professional service should look like.

What impressed us most was their commitment to education - they took the time to walk both my husband and me through every step of the process, explaining not just what they were doing, but why it mattered for our home's efficiency and air quality. It's rare to find technicians who are so patient and thorough in their explanations.

Beyond their technical expertise, Jordan and Hero showed genuine respect for our home and our comfort level throughout the entire job. They worked with care and consideration, treating our space as if it were their own. As homeowners, we've all had those experiences where workers leave you feeling uneasy - this was the complete opposite. We felt completely at ease having them in our home.

Their professionalism, kindness, and attention to detail set them apart in an industry where those qualities aren't always guaranteed. If you're looking for HVAC services you can trust, don't hesitate to call Aztil Air Conditioning. Jordan and Hero will take excellent care of you and your home.

Five stars - we'll definitely be calling them for any future needs!
Response from the owner:Thank you Jessica for your positive feedback. I'm glad you were happy with the support we provided. Please keep us in mind for any HVAC needs.
Rick was terrific. Knowledgeable fast, courteous. We hope if we need a/c work, he's the one who comes out.
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Very professional, knowledgeable, and accomplished the tasks requested..Would recommend to others.
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Jordan was excellant. Went above and beyond listening and talking me through everything.
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Thank you Alex who diagnosed my AC issue quickly,! your superior technical skills and customer service have not gone unnoticed. Alex made my experience a pleasant one, even though my AC motor went and it needs to be ordered, the good news is it’s under warranty🤷🏼‍♂️
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