Home Diagnosis and TroubleshootingClimate Control and Air Conditioning Car AC Smells Musty – How Do You Get Rid Of That Scent?

Car AC Smells Musty – How Do You Get Rid Of That Scent?

by Jordan Harris
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There’s no better way to end a hot afternoon ride than by enjoying the fresh, cold air from your vehicle’s air conditioner. However, that cold air can instantly move from cooling to repulsive if it’s blowing a funky odor. Once you notice your car AC smells musty, don’t endure the smell but try to fix it immediately.

The smell emitting from your dashboard vents stenches and is not good for your health. Sadly, bad smells from the AC system of your automobile are a common issue. This odor from your car’s AC has been interpreted in various ways as bad eggs, rotten fish, mildew smell, burning rubber, dirty stockings, fumes, and freon leak smell. It can be accompanied by the feeling of shortness of breath, headache, and drowsiness. I am sure you don’t want to experience this.

Several things can result in the breeze from your vents having an awful and unhealthy odor. Recognizing the causes and remedies for this awful smell can help bring back the cold, fresh air you once enjoyed in your car on a hot afternoon. We hope to share with you everything you will need to know about your car’s air conditioning system, how it works, and why your car AC smells musty, including how to get rid of it.

The Car AC System

This is a pair of elements that work together to exude chilliness to a vehicle’s interior. Your vehicle’s AC system functions much like the air conditioning system you use at your residence and workplace. Its active elements comprise a compressor, condenser, and evaporator.

Your automobile’s AC system is a crucial one when it comes to making your driving adventure an enjoyable one, particularly as the temperature outdoors increases. The main function of an AC system is to cool the environment to soothe everybody in the car. With this equipment, you get cooler and better rested in the midst of those scorching rays.

How The Car AC Functions

Your car’s air conditioning system uses a 4-stage process to cool the atmosphere. The refrigerant trickles through various elements and transforms from elevated to low pressure and from a liquid to a vapor.

Being a low-pressure vapor, the refrigerant takes in and ejects heat and mist from the passenger cabin, chilling the atmosphere.

The moisture it eliminates is the liquid you normally see dripping under your car when your air conditioner is functioning normally. You may have been wondering why there is always a water leak from your car’s AC. I have explained the reason.

AC Smells Musty


When you start the AC in your vehicle, do you always inhale a certain odor that is awful? If this is your situation, there is something wrong with your automobile’s AC system. Let’s discuss what causes these awful odors.

Why Car AC Smells Musty #1 – Mist

Your automobile’s AC system does not generate chilled air; it seizes heat and mist from the atmosphere outside your vehicle, making it feel colder than the atmosphere around you.

The rings in the air conditioning unit crystallize the atmosphere’s heat and mist, bringing out the humidity before lifting the chilled air into your vehicle.

As these rings are colder than the atmosphere, heated air dripping into the unit can generate moisture packs that enclose the condensing component in your air conditioning system. That, in turn, generates little pools of moisture soaked outside the vehicle through the drainer.

However, if the mist is glued or, for whatever reason, cannot find its direction out of the air conditioning unit, evaporation or drainage will compress the moisture inside the unit and around the rings, building up moisture within the air conditioning unit.

Why Car AC Smells Musty #2 – Bacteria And Mold

When your drain is destroyed, or you often use your air conditioning system, the unit will probably remain moist every time, generating a breeding surface for microorganisms. The air that passes via the evaporator and the unit’s mold accumulation will send the awful odor inside your automobile through the sprinkle holes.

Mold and bacteria are the very common reasons your car AC smells musty. As your car gets rustier, mold can begin to develop. When you don’t often use your air conditioner unit or use it more frequently, it can also heighten the development of these microorganisms inside your vehicle’s air conditioning system or vent.

Smell-inducing mold likes to live in your car’s unit, and the reason is that the unit is often damp and dark.

Car AC Smells Musty – Other Possible Reasons

The next likely contributor to this awful odor coming from your vehicle’s air openings could be stuff carried into the vehicle, like meals, vinegar, animals, fumes from cigarettes, etc. As the air is re-distributed throughout the compartment, the particles that give off the original fragrances will get trapped in the compartment’s air filter and can build up as time goes on.

Cigar fumes especially have a way of saturating everything in your car interior and are often impossible to eliminate. It is no wonder that as time goes on, the recirculating of the fumes, coupled with the fractions that get tossed back into the atmosphere from seats and other minor sources, get entrapped inside, and this can begin to accumulate in your compartment’s air filter.

Suppose you leave this to collect for an extended period of time. The air filter can become so congested that it inhibits airflow considerably, which disturbs other elements in your air conditioning system and will reduce its lifespan. The same way you replace your car’s air filter at frequent intervals is the same way you should replace your vehicle’s compartment air filter.

Oil and antifreeze leakage can cause a smell in your car once the CCS air inlets on your windscreen pick up the odors and transmit them into the car. The exhaust system can emit a disturbing smell that the CCS air inlet can transmit into the car and pollute the air. If the catalytic converter is not working well, the smell of hydrogen sulfide in the form of a rotten egg smell can ooze out of the exhaust system and be carried into the car by the CCS air inlet.

Types Of Car AC Smells And Their Remedies


Car AC Smells Musty, Other Bad Smells #1 – Stuffy Air Smell

This smells like a musty gym bag. The odor results from the accumulation of debris and bacteria in the air conditioner pipework induced by a dirty compartment filter. It is the dominant cause of awful AC odors.


Changing the compartment air filter is a quick and cheap DIY repair you can perform. You can review the owner’s guide for comprehensive instructions.

Car AC Smells Musty, Other Bad Smells #2 – Sweet Smell

Inhaling a sweet smell in your vehicle’s air conditioner could suggest an antifreeze leak in your cooling unit. Ethylene glycol is an element in antifreeze that makes it fantastic at reducing the freezing temperature of the water. Also, the exact element offers antifreeze with its funky sweet smell.


Trickling coolant can be harmful to your automobile. If you inhale something sweet in your vehicle’s air conditioner, it is crucial to take your automobile immediately to an AC specialist for a thorough automobile inspection.

Car AC Smells Musty, Other Bad Smells #3 – Musty Or Mildew Smell

Musty or mildew odors occur mostly due to the accumulation of mud and debris in the under-cover air intake duct, which traps moisture on the air conditioner evaporator and the cover. Several awful and unhealthy microbes, like bacteria, mold, mildew, etc., can infest and thrive in that wet but trapped dirt. So, it’s good to learn how to get mildew smell out of car.


You can eliminate the musty car smell by washing out the air conditioner evaporator cover through your car’s air intake using a domestic disinfectant and then tidying the vents with your car vent cleaner or an anti-bacterial spray.

However, this is best handled by professionals. They utilize commercial-level bacteriostats and microbes to wipe out spores and other pollutants that cause awful odors from your air conditioner.

When you cannot detect obvious water trickling from under your automobile when your air conditioner is in operation, it means that the AC’s evaporator cover drain cavity is packed with leaves, trash, mud, etc. Review the owner’s guide to spot the drain area. Some automobiles have a little rubber hose fixed underneath the firewall close to the middle of the vehicle.

To empty that debris, use a 12-hairsbreadth chunk of a wire coat hook with a one-quarter-inch 90-degree curve at the edge and carefully put only the curved edge of the cord into the hose. Coil the cable back and forth and remove any sludge obstructing the duct. If the duct cavity is under your vehicle, you can involve your mechanic to clear it. Sterilize the air conditioner cover after cleaning the clog.

A sealed air conditioner drain can also result in water dripping into the passenger cabin, drenching the mats, and creating the perfect habitat for bacteria and mold to thrive.

Car AC Smells Musty, Other Bad Smells #4 – Freon Leak Smell

Freon is a CFC that lets your air conditioner eliminate heat from the atmosphere to keep you chilled. However, it can be toxic to your health if it is not enclosed appropriately. Freon often travels through locked copper spirals in an air conditioning unit, but these rings can break, resulting in an air conditioning coolant leak. A freon leak will exude between a sweet and a chloroform odor.


Freon leak smell can be harmful to human health. If you suspect a freon leak, contact an AC specialist who can utilize a freon leak sensor to assist in addressing the problem.

Car AC Smells Musty, Other Bad Smells #5 – Gas Leak Smell

Do you inhale gas each time you put on your vehicle’s AC? Then gas might be leaking from your vehicle. When you switch on your air conditioner system, the gas odor is sucked into the neat air the AC receives.


To fix this issue, you will need to mend the leak. There are various spots where you can check for a gas leak. Check the fuel pressure regulator of your engine to see if the leak is occurring there. Also, you can inspect the fuel injectors in the engine cabin for any leaks.

Car AC Smells Musty, Other Bad Smells #6 – Messy Air Filter Smell

Your car’s air filters may also be causing an unusual AC smell. If you don’t tidy it appropriately, the air filter can accumulate filth, stale moisture, dust mites, and other toxic contaminants. That can lead to an awful smell whenever you switch on your AC.


You can easily rectify this issue by simply removing the old filter and replacing it with a new one. Also, you need to clean the air filter of your AC unit frequently.

Car AC Smells Musty, Other Bad Smells #7 – Vinegar Smell

Does your car AC smell like vinegar? Do you often inhale raw vinegar when cooling down your vehicle? While this awful smell is undeniable, its origin may be a little complicated. Specific mold can stimulate your automobile’s AC unit to smell like vinegar.

Other factors could also result in awful smells in your air conditioning, like ozone layer emissions, which tend to give off a vinegar odor, or trickling battery acid, which possesses a sharp sulfuric odor.


If your car vent cleaner doesn’t eradicate the vinegar smell problem, it’s reasonable to have an AC specialist check your air conditioning unit.

Car AC Smells Musty, Other Bad Smells #8 – Ozone Smells

Electrostatic air distills, emits ozone, and oozes a smell close to that of chlorine. That poses a threat to human health if inhaled heavily. Some individuals may suffer from chest discomfort, while others may experience difficulty inhaling and exhaling.


Study your holder’s guide and regulate your air conditioning unit to remedy the issue. Contact an AC expert if the smell continues.

What To Do If Car AC Still Smells Bad

Have you tried inspecting your duct tubes and cleaning out mold yourself, but to no avail? Well, all hope is not lost, and you don’t even need to buy a new vehicle. However, you might need to reinstate the air conditioning unit in your automobile.

Take your vehicle to a trusted automobile dealership or AC repair store to have your air conditioning unit examined as fast as possible.

Car AC Smells Musty – How To Fix It

Before successfully eliminating bad smells from your car’s AC, you need to identify the real cause of the smell. Once you’ve identified the cause of the smell, you proceed to eliminate it. For example, if the cause of the smell is mold and bacteria build-up, follow these steps to remove the smell.

Step #1 Switch off your car’s ignition and all the AC outlets, and spray healthy and nice smelling clean air duct treatment into every corner of your car. Don’t forget to spray some inside the AC vents.

Step #2 Switch on your car engine again and set the AC to the maximum fan level. Then find the recycling intake duct on the floor of the passenger side, and spray some clean air duct treatment inside it to suck it into the system.

Step #3 Change your setting from maximum air to fresh air so that there’ll be an intake of fresh air from outside to saturate your car. But you’d need to locate the fresh air grill below your windshield and spray some air duct treatment into it. Finally, open the doors (once you’ve learned how to open Tesla door) to allow fresh air into your car.

How To Help To Stave Off Musty AC Smell In Car

When you integrate an antimicrobial agent into rubber, foam, filters, and gluey elements of your vehicle’s air conditioning unit, mold won’t be able to accumulate in the first place.

Foams used in automobile air conditioning units treated with antimicrobials stop mold development and curb musty odors. Foams used in automobile air conditioning units that are not treated will develop mold and can contribute to a mildew smell in cars.

Last Words On Car AC Smell Musty

An AC is one of the vital units in cars that bring relaxation to riding during summer. A bad AC smell is a total turn-off and needs to be fixed, hence the reason for this article. One of the ways to also get rid of the musty smell from your car’s AC is to avoid using acidic drain cleaners to rinse your air conditioning system. You’ll damage costly and hard-to-replace air conditioning elements.

Stop operating your air conditioner only in the recirculated style. This style hinders fresh air outside from penetrating the air conditioning vents. Fresh air can assist in drying up extra moisture.

FAQs On Car AC Smell Musty

What Does Freon Smell Like

Freon travels mostly through the sealed copper rings in an air conditioning unit, but these rings can break, resulting in an air conditioner coolant escape. A freon leak will evoke an odor somewhere between sweet and chloroform. And they can be harmful to human health.

How To Fix AC In The Car

Start your car and switch on the AC, then check to see if the compressor is functioning. Inspect the wiring directed to the compressor, and look for leaks in the AC unit. Buy the exact type of refrigerant for your car. Inspect a thermometer for ambient conditions. Find the downward-side service dock for the AC and borrow a rag to wipe the region around the dock. Connect the charging hose to the downward-side service dock. Utilize the ambient atmospheric pressure table on the instrument to deduce pressure. Perforate the sealer on the container and keep the container upright. Check for leaks in the refrigerant, then withdraw the charging hose and reserve the container in a cool place. Send your automobile in for a fix if need be.

How To Get Rid Of A Musty Smell

Blow condensed air from an interval to guarantee that interior elements do not get destroyed. Use a scrub to wipe the finer dust specks on the face and back of the component. Tidy the duct and the vent properly with some cleaning mixture, then wash out the mixture with liquid.

How To Get Mildew Smell Out Of The Car

To eliminate a mildew smell from your automobile, use a damp or waterless vacuum on the rugs and seats. For a straighter and sharper solution, you may utilize a hair dryer. Again, if the mildew smell is very intense, you can spray some baking soda on the affected region and allow it to immerse for 2 hours before cleaning it off.

Why Does My AC Smell

If you’re experiencing an AC musty smell or a pungent smell like that of vinegar, it might be due to numerous problems like a messy filter, extreme moisture, or a blocked condensate panel or soak line.

Why Does My Car Smell Like Vinegar

One major explanation why your vehicle ducts smell like vinegar is bound moisture. That may occur from either too much use or mishandling of your car. Additional causes of vinegar smell could be the accumulation of mold or bacteria, wrecked drain ducts, gas leakage, etc.

How To Stop Smells From Coming Through Vents

Baking soda is the perfect remedy for smells emanating from your AC ducts, as it generally engulfs all kinds of odors. If your air conditioner smells awful and the smells are emanating from inside the vents, you may need to sprinkle the baking soda in the interior of the vent work for maximum potency.

How To Fix AC Leak In Car

Use a super sealant. It is a cheap, fast-fix means of sealing minor leaks in AC units. You can get the super sealant in virtually any vehicle component shop. Also, repair the evaporator because no amount of super sealant can remedy any leak from the evaporator. It’s either you work on it or you change it. You can cut and rumple the duct to repair pinhole-size cracks. A little soldering can assist in this concern. If the perforation is larger, getting a new evaporator will be the only remedy. You will need to remove the dashboard to arrange the evaporator. You will also need to clean the unit before reloading it.

How To Get Milk Smell Out Of The Car

Spray a large coating of baking soda over all the wet patches of the vehicle. Allow it to stay overnight so the baking soda can drain out those unpleasant odors. At daybreak, clean up the baking soda. When you do this, you will notice a big change in the smell of your vehicle’s interior.

How To Get Mold Smell Out Of The Car

Clean all vehicle surfaces before you begin. Apply baking soda. Ensure you use a strong vehicle mist cleaner and a soft detergent. Apply refined white vinegar to go over the cleaning again, and don’t ignore the engine inlet.

How To Clean Air Vents In Cars

Sprinkle condensed air into the ducts. To suck that loose dirt out of the vents, use a powerful damp or waterless vacuum and clasp it against the duct lid. Run the vacuum carefully to remove all the dirt. Then clean the duct slots with a cloth. Replace the vehicle’s cabin air filter.

What Does Battery Acid Smell Like

What battery acid smells like depends largely on the kind of battery and the individual inhaling it. The smell can be likened to several kinds of stuff. One of the most popular descriptions of the odor of battery acid is that it smells like sulfur. Some folks also say that it smells like vinegar. That is because most battery acid contains sulfuric acid, which possesses an odor comparable to vinegar.

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