Why Is There a Bad Smell Coming from Your Air Conditioner?


Are you noticing any unpleasant smells coming from your air conditioner? Is it not cooling your home like before? You are not alone. Bad odors are common in AC units, but you must resolve them quickly to avoid health issues. At Custom Comfort Air, your comfort and safety are our priority, and we are here to help you understand why your air conditioner smells bad and why you need a professional’s intervention.

Call 281.342.2512


Mold And Mildew

One of the biggest causes of an air conditioner’s stinky smell is mold and mildew growth. Mold and mildew love humid, dark places and that’s exactly what the inside of your AC unit contributes to – a dark, humid space. Over time, moisture will accumulate and mold and mildew can grow on the evaporator coils, in the drip pans or perhaps even in your ductwork itself. When your AC runs, that mold and mildew begins to get blown around your entire house leaving you with a moldy, mildewy stench.

Clogged drains

The line located between the filter and upper coils: It’s likely you’re experiencing stinky air due to a clogged drain line leading outside your home – the main drain line gets rid of water that naturally forms from your AC. If the line is clogged by dirt, debris, or algae, water will start to back up, causing it to stagnate and start emitting the smelly water.

Dirty Air Filters

Air filters are there to improve your air quality by catching dust, pollen and other particles in the air. However, if your air filters are too dirty or clogged they will no longer be able to trap the particles.

Unfiltered particles can begin to collect in your AC system, which will result in a stale or dusty smell when the system is running.

Dead animals

A sickly odor could signal the presence of a dead animal in the ductwork or near the outdoor air conditioner unit. Rodents or birds can infiltrate and get trapped in the system.

Chemical Odors

If you detect a chemical or burning smell coming from your air conditioner, it could indicate a more serious issue such as an electrical problem or a refrigerant leak. In such cases, it’s crucial to shut off the AC immediately and contact a professional technician for inspection and repairs.


Why Seek Professional Assistance:

Although the temptation might be to try some DIY remedy or simply turn a blind eye, your best bet will always be to call in a professional technician. Here’s why.

The aid of an expert

A trained technician will accurately diagnose the cause of the bad smell and prescribe the proper solution, so you won’t have to waste time trying useless remedies.


Many problems such as electrical issues or refrigerant leaks pose a risk to your family and you. It’s best to leave these problems to a professional technician who has the experience and tools to proceed safely.

Preventative Maintenance

It is advisable to have a professional perform regular maintenance on your air conditioner to prevent future problems from developing and extend the life of your system. For example, an air conditioner unit includes many components that require cleaning, identifying leaks, and ensuring proper airflow.


A new AC unit may still be under warranty when something goes wrong. Unless repairs are done by a qualified technician or an approved/authorized company, your warranty may be voided.

In conclusion, a bad smell from your air conditioner can indicate various issues ranging from mold growth to more serious mechanical problems. Rather than trying DIY fixes or ignoring the issue, it’s best to contact a professional technician for a thorough inspection and timely repairs. At Custom Comfort Air, we’re committed to keeping your home comfortable and safe. Don’t hesitate to reach out to us for all your HVAC needs.

Call 281.342.2512