Why Does My Air Conditioner Smell?


During hot summer months, most households depend on an air conditioner to maintain comfortable indoor temperatures. Your AC will efficiently function if you take good care of it. However, when neglected, it could lead to some inconvenient problems.

One of the most common issues that people face with their AC is foul smells. Imagine that you come home after a long hot day, turn on your AC, and an awful stench fills the house, so you have to turn it off. It’s more than just irritating since it affects the overall comfort of your home. These issues indicate a more significant problem within your AC. Here are some reasons why your AC could potentially produce strong smells.

1. There Is a Leak in the Refrigerant Line

Although your air conditioner doesn’t run on an internal combustion engine, it contains some fluids, and when heated, they produce exhaust fumes. Whenever you smell such exhaust-like odors from your system, it means that there is a fluid leak.

Such a condition can affect the performance of your AC, so you need to turn it off, open the windows for ventilation, and call a professional immediately. The fumes may contain toxic gases, and when inhaled, they can deplete oxygen in your body, which is life-threatening. Such gases are also very harmful to the environment.

2. Something Could Be Burning

If the AC produces a burning smell, it means that something is heating up. Note that an AC contains lots of electrical components like wires, compressors, fans, and the circuit board. Sometimes, the smell could be caused by melting plastic parts. Other times, your AC may produce an odor reminiscent of gunpowder, indicating that you could be dealing with a shorted circuit board or fan motor.

These fumes may contain harmful metallic and chemical components that can pose potential dangers to your respiratory system. Immediately turn off the unit and call your local HVAC expert. Note that attempting DIY projects on electrical components can result in severe injuries.

Your AC can also produce a burning smell when left unused for an extended period. Dust accumulates, and once you turn the unit on, the dust burns, producing an awful smell. The odor should go away after a short period, but have the AC checked by a technician if it persists. Still, it’s a good idea to schedule maintenance services for your unit before the beginning of the summer season to avoid such issues.

3. Dead Insects or Critters Are Stuck in the AC

Insects, rats, mice, and even birds may find shelter in the dark components of the AC. Some might get stuck in there, die, and begin to decompose. This causes a terrible rotten smell that fills your house once you turn on the unit.

To fix this issue, you will need to determine the specific duct where the stench is coming from, which can be tricky. Seek professional help, and the expert will help get rid of the dead animal, clean the unit, and restore fresh smells to your house. Note that insects and critters can also damage your AC, so you should have it often checked to avoid such scenarios.

4. There Is a Gas Leak Within the System

The AC uses a natural gas which is usually odorless. However, manufacturers add a chemical, methyl mercaptan, that has a distinctive rotten egg smell. This helps to ensure immediate detention of gas leaks. If it leaks and you turn on your AC, the gas causes your entire house to stink. You shouldn’t take this smell lightly. Once you inhale high levels of this gas, it can lead to loss of consciousness or even death. It’s also highly flammable and explosive, which can cause massive damage to your property and endanger your house occupants.

Once you detect sulfur or a rotten egg smell, don’t light matches or lighters or operate any electrical devices. Put out any open flames or candles, open all doors and windows in the house, and turn off the gas supply. Evacuate the building, and contact your HVAC company to address the issue.

5. Mold and Mildew Growth in the AC

A clogged condensate pan and stagnant water can also produce a smell similar to dirty socks or stinky feet. Note that, in addition to cooling your home, your air conditioner removes excess moisture from the air. When it fails to drain properly, this creates a perfect condition for mold and bacteria to grow. The only way to fix this is by finding the mold buildup and cleaning it up.

If you can’t see it, call your HVAC technician to clean the condensate lines to ensure the proper functioning of your AC. Exposed ductwork in the crawlspace and basement can also cause mold issues, so you might need to insulate them. If you reside in a humid area, a dirty filter can make your AC circulate a stale smell. Once the filter becomes clogged, it traps moist air, which attracts mold and mildew growth. Hence, change or clean your filters often.

6. You Smoke in the House

If someone smokes in the house, the smell could accumulate in the filter and the evaporation coils. Once you turn on the AC, it recirculates a stale cigarette smell, which could cause headaches and allergy symptoms. To eliminate the smoke smell from your house, change the filters. You can also restrict people from smoking in your home and encourage them to do it outdoors.

7. The AC Has an Oil Leak

If you notice an oily smell coming from your AC, chances are good that there is an oil leak. You should have an expert tighten fittings in the oil tank, filter, or line. If there is no sign of an oil leak, have the professional check the burner for any issues. Sometimes, it can malfunction because it is clogged or because the fuel pump has malfunctioned. Also, freshly delivered heating oil can cause faint odors for a short period that should dissipate independently. It mainly happens if your delivery team spills some oil while refilling.

Call the AC Service Professionals

Regularly cleaning your AC and scheduling proper maintenance and servicing can help prevent awful smells. Once you notice any of the smells outlined above, you shouldn’t try covering them up with air fresheners or scented candles. It will only worsen the air quality. You might even begin to experience breathing difficulties, headaches, or eye and nose irritations.

Also, ignoring such warning signs could cause more damage to your unit, resulting in expensive repairs or replacements. Next time you experience or notice awful smells from your AC, schedule the unit’s inspection with professional technicians. They can assess the problem to identify and fix any underlying issue to prevent the odor from returning.

If you need professional help with your AC, you can always reach out to Huft Home Services. We offer a wide range of services, including air conditioner and furnace repair, installations, and maintenance. Our company also deals with bathroom remodels, water softeners, insulation, water heater repairs, and replacement services in Sacramento, CA, and the surrounding areas. Call us today to book an appointment.

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