Clearing the Air: A Deep Dive into Understanding and Eliminating Air Conditioner Odors

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Updated on:

July 10, 2023

Smell Dilemma: Understanding and Solving Air Conditioner Odors

Maintaining your air conditioning system is a crucial part of having a comfortable and pleasurable driving experience. It is also important to take care of the air conditioning inside of your home. Maintenance of air conditioners is especially important during the summer since mold and other bacteria thrives in heat and humidity. Unfortunately, if you overuse the ac system, this can damage the air conditioning unit and cause a bad smell that will spread throughout your whole home or vehicle.

There are a lot of different types of musty ac smell that you might get after damaging the ac unit. It could have an unpleasant smell like a rotten eggs smell, burning odor, gas smell, and other uncomfortable and unpleasant odor that can cause headaches and dizziness. Each of these smells suggest different reasons to make your air conditioner smell bad in your home.

In this article, you will learn what causes each of these musty smells, and how to get rid of the air conditioner smells.

Key Takeaways:

  • Maintain your air conditioning system regularly to prevent unpleasant odors caused by mold and bacteria growth in hot and humid conditions.
  • Different odors indicate various issues with your air conditioner, such as burning smells, rotten egg smells, and musty or moldy odors. Identify the specific odor to understand the underlying problem.
  • Clean your air conditioner regularly and address issues promptly. This includes cleaning the indoor unit, condensate drain line, and outdoor unit, as well as replacing dirty filters. Consider investing in an air purifier to improve indoor air quality and prevent odors.

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Table of Contents (Show)

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principle of air conditioning unit
AC work principle

How does the air conditioning unit work?

Your air conditioner does not actually create cold air. What it does is take moisture and heat out of the outside air, therefore making the air inside of your home colder. The ac unit coils then condense the air's moisture and heat. This process removes the humidity before sending the cold air inside your house through the ac vents.

Since this air conditioning breeze is much colder than the surrounding air during a hot summer day, the air entering into the unit can create moisture that impacts the condensing components in your central air conditioner. This process also forms a small stream of water that drips out of the home through an ac drain pipe. However, if you have overworked the ac unit, the moisture might fail to find a way out of the home by evaporation or draining properly. This can cause the water stream to drip into the air conditioner unit that surrounds the coils and result in moisture inside the house that can cause the air conditioner smell bad.

This is one of the things that can cause air conditioner smells. We will explore more reasons below.

Five common AC smells explained and what causes air conditioner smells?

There are a bunch of different things that can cause a bad odor to come out of you air conditioner. It is important to immediately find out what the smell is and why you have it since it can be a health hazard. Here are some of the most common ac smells that people frequently run into:

Burning smell from AC unit
Burning smell from AC unit

1. Burning smell

If your ac smells like electrical odor or burning smells could suggest that you have a mechanical problem with your ac fan or compressor, wiring issues, or electrical component failure. Being exposed to such smell for a prolonged period of time is very unhealthy.

To check if this smell is just dust burning off or an electrical issue, observe the burning smell for 20 to 30 minutes. If that smell disappears after that amount of time, it was just dust burning. If the smell electrical still lingers after 30 minutes, call a professional HVAC technician immediately to check the electrical parts of the air conditioner and the HVAC system and make necessary repairs.

Please note that attempting to fix the electrical problem by yourself could be very dangerous and unsuccessful, so it is better to call a skilled professional.

Rotten egg smell
Rotten egg smell out of AC

2. Rotten egg smell

Smell of rotten eggs, provided that you do not have any rotten eggs in your home, indicates that you have a natural gas leak. On its own, natural gas is odorless, but usually utility providers put in methyl mercaptan that alerts people about a dangerous leak through its distinctive odor.

While low exposure levels to natural gas is not dangerous to your health, high levels can reduce oxygen levels in the blood and can lead to unconsciousness or even death. This is why it is important to take some precautions if you smell gas. First, make sure that you you turn off the gas supply. Immediately after, contact a gas company. Make sure that you are not using any lighters and matches. Open up all windows and doors and exit your home.

If your air conditioner smells like rotten eggs, it can also indicate that there is a dead animal stuck in your ac unit.

Moldy or musty smell
Moldy or musty smell

3. Moldy or musty smell

This is one of the most common air conditioner smells. If your air conditioner smells musty, it is most likely cause by an accumulation of water in the drain line and drainage system. Such problem with a drain like can cause mold, fungus and mildew growth which is what makes the ac smells musty.

Another cause for a musty smell could be because you have a dirty air filter. This is most common if you live in a hot and humid climate. If you turn on your air conditioner for a long time, a lot of moisture can develop in the filters, requiring a change of the ac filter.

You might have heard of a dirty sock syndrome. If your air conditioner smells like dirty socks, it is because mold and mildew are seeping from tour air conditioner when you first turn it on.

Preventing this syndrome will require calling a heating and cooling company for them to clean your refrigerant lines and ducts.

If you central ac smells musty, this could also suggest that you have a dead animal stuck in the unit.

Car exhaust fumes smell
Car exhaust fumes smell

4. Car exhaust fumes smell

If your air conditioner smells like exhaust fumes, this indicates that the air conditioning system in your home has a refrigerant leak. A refrigerant is a cooling agent inside your air conditioner. The leakage of it can impact the performance of your ac and also release harmful chemicals into the environment.

Sweet and chemical smell also indicates a refrigerant leak. The HVAC system of your air conditioner relies on the gas to shift heat through the copper coils, which with time passing can break down. You should also take extra care if you notice a freon smell and there is a leak.

When your air conditioner smells bad, like car exhaust fumes or has a freon smell or sweet chemically smell, it is best to call a HVAC repair technician to check for the leak.

Learn more how to remove smoke smell from car in our detailed guide.
Cigarette smoke smell
Cigarette smoke smell

5. Cigarette smoke smell

If you are a heavy smoker and tend to smoke cigarettes in your home or car, you will notice that eventually your air conditioner will end up smelling like smoke. Cigarette smoke bacteria buildup is usually the reason for this smell, which can cause headaches and allergic reactions due to poor indoor air quality.

An air filter and evaporator coils tend to absorb the cigarette fumes. When you turn on your air conditioner, the tobacco particles become loose and get distributed all throughout your house or car.

You need to clean the evaporator coil and change the dirty filters every 30 to 60 days in order to remove the smell.

Check our selection of best ozone machines for odor removal.
cleaning your air conditioner

How to clean your air conditioner to get rid of smells

If your central air conditioner smells bad, the best solution to do is clean it. Depending on what smell you have, you should first call a professional to check for any leakage or any mechanical damages. After everything has been fixed, you can proceed to cleaning the clogged up air conditioner.

Step 1: Turn off the ac units

For safety purposes, this should be the first step you make. You may want to unplug the power cord it is possible to be on the safest side.

Step 2: Throughly clean the indoor unit of your air conditioning

You can start cleaning the interior of the unit once your air conditioner is turned off. Start by taking out the door that is located on the side of the appliance; you might need a screwdriver for this.

Following that, you can clean the evaporator coils by rubbing them with a soft brush or cloth to get rid of any visible dust.

After that, go to the following step by taking out the drip tray, which should be located underneath the coils of the appliance. You might even notice some water and mold in it.

Your drip pan is no longer functional if it has mold growing inside of it. You should contact an HVAC technician to replace it.

To complete this step, clear out thee evaporator line. You can accomplish this by sucking out anything that may be inside of it with a wet vacuum. Your evaporator coils should be located close to the air handler.

Step 3: Clean the condensate drain line

Cleaning out the condensate drain line on your air conditioner is the next task you may tackle. The first step in this procedure is to stick your finger up the drain line to check for any obstructions that you can remove that way. The air handling unit, which is frequently in the garage or attic, should be close to the condensate drain line.

You should also take the vent tee off and clean it as part of this operation. This is a crucial access point that might have buildup.

A wet/dry vacuum can be used to remove any obstructions in this area. You might need to encircle the end of your vent tee with something like a wrap depending on the style that you have.

Once all materials have been removed using a vacuum, flush the condensate line fully with water to ensure that it is empty. Even some vinegar can be used to remove any remaining buildup. If you allow it to sit for around 20 to 30 minutes, a couple cups should work as a drain cleaner.

To keep yourself from running into the same problem in the future, you should use drain pan tablets so that the growth that you have cleaned does not come back.

Step 4: Locate the air filter and replace it

Another location to check is the filter if you want to get rid of smelly air conditioner problem. It usually sits next to the thermostat or the air handler. It might be in the ceiling, behind a window, on the floor, or even inside your walls. It just relies on how your house was built.

Hold your palm up to the vents in your home while the AC fan is on if you need aid locating the return vent where your air filter might reside. A return vent is what you can feel as a suction sensation.

The fan and the motor for your system are both housed in a sizable metal box called an air handler. The filter will be inside of it.

Your air handler may contain instructions on how to insert the filter, so keep that in mind, so when you're inside, make sure to look.

Once you have found the filter, you can start the replacement process.

Step 5: Clean the outdoor unit of the air conditioning

To start off this process, take off the top of the condenser unit. Once you have done so, you can start the cleaning.

Fist, use a vacuum to suck up things like grass dirt and leaves. You can also use compressed air to clear out debris in hard-to-reach places. Just be careful to do it from a distance to avoid injuring any internal components.

A little brush or cloth can be used to remove any remaining debris.

Step 6: Clean out fans and air conditioning coils

For this step, you should use a coil cleaning solution.

To dilute the cleaning solution, adhere to the instructions on the bottle. Apply it to the coils after adding it to your pump sprayer. Within a few minutes, you ought to notice it begin to foam, and once it has, you may spray it off.

Make sure not to use a pressure washer for this because it can harm the sensitive fins.

Step 7: Spray down the unit

Entirely spray down the unit to get rid of any remaining dirt and dust. You should also flush out the drip tray to get rid of any dust or debris that may have gathered.

Do not use a pressure washer for this step.

Step 8: Finishing touches

Let the unit dry completely. Once that is done, rearrange all the part of the ac system.

maintenance and cleaning of ac unit

How to stop the reoccurrence of central air conditioner smells

Below are some tips that you should follow to save your air conditioners from getting musty smells.

1. Clean often

Air conditioner smells mean different things and indicate different issues. To successfully improve the indoor air quality and get rid of any ac smell, you should clean it, and do so often.

2. Maintenance

Be consistent about maintaining your HVAC system. Schedule regular checks to make sure that none of the parts of the ac system are damaged.

3. Invest in an air purifier

An air purifier removes hot/cold spots, lowers dust and allergens and increases the longevity and efficiency of your HVAC system.

Also check our guide for choosing best ozone generator

About the Authors

Koren Zitser
Vip Air, Panama: 20+ years in global AC excellence. Partners with industry leaders, offers split to large-scale systems, specializing in VRF, Multi V, maintenance, and innovation.
Kristina Tretyakova
Distinguished as a South Florida Top-10 student in 2021. Studying Marketing and Business Administration at FIU. Proficient in daily operations and skilled in cleaning, auto detailing and copywriting.

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