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Why Does My Car AC Smell Like Feet?

These days, having an AC in a car has become more of a necessity than a luxury. With temperatures soaring high outside, all everyone can think of is reaching for the AC button the moment they step inside the car. The last thing anyone would want is to be welcomed by a dirty foul smell whenever they switch on their car’s AC.

Then they find themselves in a situation where they are battling the decision of either keeping the AC off and dealing with intense heat or switching on the AC and breathing in the foul smell of the AC. Does this situation seem similar to you? If yes, you might be looking for reasons why your car AC smells like feet and would want a definite solution to get rid of the same. This article will tell you all there is to know about such an issue and highlight some effective ways to resolve the same.

How Does a Car AC Work?

AC or air conditioning in your car cools the interior area of your automobile. It follows a four-phase cycle to do this. Basically, the refrigerant flows from one component to the other, changes its pressure from high to low, and takes the form of a gas from liquid. This low-pressure gaseous refrigerant absorbs the moisture and heat from the automobile interiors and expels it. This cools the air inside the automobile. The moisture removed through this process can be seen as water trickling under your car when the AC is running.

Why Does My Car AC Smell Like Feet?

If your car’s AC is smelling like feet, the most common cause behind this would be the built-up moisture. The air conditioning in your car works by absorbing heat and moisture from the air. The water vapor collected undergoes the condensation process, and this is expelled out through the car’s drainage hose. Some moisture can easily get trapped inside the car’s air conditioning system during this process. In such damp conditions, microorganisms start thriving and this leads to the build-up of mildew and bacteria. When this happens over a prolonged period of time, it can result in a foul or feet-like smell from your AC.

What Are The Other Different Smells in the Car AC?

Some common types of smells from your AC and the reason behind each of them have been described in detail below.

1. Stuffy, stale air

This smell is similar to that of the smell coming from an old gym bag. This happens when the cabin filter of the air conditioning system is dirty, which causes bacteria and dust to build up in the ducts of the AC. This issue can be easily fixed by replacing the cabin filter.

2. Musty, Mildewy

Such a smell can result from dirt buildup under the air intake vent. This would result in trapped moisture on the evaporator case of the AC. In such a moisture-rich environment, mold, mildew, and germs can quickly grow and cause foul smell. You can resolve this problem by flushing the AC evaporator case and cleaning the ducts. Although this may seem simple, it is recommended that you leave this to the professionals.

Whenever you observe that clear water is not dripping from under your car when you leave the AC running, it means that the drain hole of the AC evaporator case is clogged with unwanted gunk. For this, you must first locate the drain hole and then use a wire coat hanger to clear it. If the drain hole is located under your car, it is better you take it to your car’s service provider.

When the AC evaporator case’s drain hole gets clogged, it can even lead to a water leak inside the passenger compartment leaving the carpets wet and making it a perfect environment for mold to grow and thrive.

3. Chemical Odor

When a moldy smell is combined with a chemical odor, the refrigerant is leaking from the AC evaporator. If you switch on your AC, and hear the fans blowing, but there is no cool air coming out, it would mean that the refrigerant is leaking and has caused dirt and dust to get trapped on the evaporator fins which is restricting the cool air from the vents. The evaporator of your car’s AC would generally be under the AC instrument panel and this is why this issue would need to be fixed by a professional.

4. Sweet Pungent Odor

If you observe a sweetish smell when you turn on your car’s AC and also see a slimy film on the car windows, it would mean that the engine coolant is leaking from the heater core into the air conditioner ducts. You can ask your mechanic to install a new heater core to fix the problem.

5. Gasoline

Although the cabin filter in your car can effectively filter out debris and dirt, it cannot filter out smells like gas. If your car has leaking gas, you will smell it as it will get sucked into the interiors through the AC. If you ever smell gas in your car, the first thing you must do is switch off your car and get it towed to the nearest service centre as it can be pretty dangerous.

6. Vinegar

If you are getting a vinegar-like smell when you switch on your car’s AC, it can be pretty tricky to exactly pinpoint what might be causing it. Certain types of mold can give out a vinegar-like smell. There are few serious issues that can also lead to such a smell like ozone emissions or a battery acid leak. Try using a duct cleaning spray to get rid of this smell. If this does not work, it is best to get your car inspected by a professional.

7. Burning Smell

It is never a good sign when you get a burning smell inside your car when you switch on the AC. When you know the type of burning smell, you can react accordingly. A few common types of burning smells are listed below.

8. Burning Oil

There can be an oil leak from your car’s hoses, gaskets, or the oil filter. When this leaked oil comes in contact with a hot engine or some other element of your car that is very hot, it can emit a burning oil smell through the AC.

9. Burning Rubber

When the AC compressor or its clutch has an issue, you can smell a rubbery odor when you switch on the AC. This can happen even when the pulley is not aligned correctly. Such issues make the belt drag which produces friction and causes a burning rubber smell.

10. Burning Plastic

When there is excessive dust settled in the vent, hose or wire is burning, or there is an electrical short, you can smell plastic burning when you turn on your car’s AC.

11. Rotten Eggs

Bacterial or fungal growth in your AC can lead to a rotten egg smell in the car interiors when the AC is running.

12. Exhaust

Exhaust smell is similar to the smell of smoke or polluted air. Generally, if your AC vent is giving off exhaust fumes or smell, the refrigerant liquid has leaked. When this happens, you will also notice that the AC is not cooling the car interiors effectively.

13. Dusty

This is more of a physical phenomena than a smell. In case you observe that your AC vent is blowing out dust, it means that dust has accumulated and has been sitting around in some part of the AC for quite some time. It can be pretty annoying when you turn on your AC and dust fills inside the car instead of cool comfortable air. Generally the dust would clear out after a few minutes. However, if that does not happen there might be an issue with the air filter.

What Are The Reasons for the Smell in the Car AC?

You may wonder why your car smells of dirty feet when you switch on the AC. Here are a few reasons why that may be happening.

1. Dirt & Bacteria

When dirt, dust, and debris accumulate over a long period of time, it can lead to several unpleasant smells in the car. Due to the accumulation of unwanted matter, the airflow also gets restricted. This can cause the air coming out from the vents to have excess moisture in it. Such an environment can cause the bacteria to grow and thrive, and this can be a leading cause for the dirty feet smell in your car. With excess bacterial growth, your car can start smelling like urine.

2. Improper Use of Vinegar While Car Cleaning

Using vinegar while cleaning different parts of the car’s AC is a common practice. When parts like evaporator coils have mold build-up, it can be cleaned effectively with vinegar. However, some residual vinegar may be sitting on that component after cleaning. When you turn on the AC, the air passes through these components with residual vinegar on them, and the smell is picked up and then spread to the car interiors through the vents.

Another reason can be that when the residual vinegar and moisture react, it produces acetic acid, which can lead to a foul vinegar-like smell inside the car. Also, when you do not dilute the vinegar before using it to clean the AC components, it can cause a foul odor from the AC vents.

3. Electrical Problems

When there are some electrical issues in your car’s AC, it can cause a burning smell. When there is an electrical issue, it can lead to the AC components getting overheated, which can melt or burn plastic wires and even liquids. This smell gets picked up by the air and is then blown out through the AC vents into the car.

Even when it is a short circuit, it can burn the insulation around the wires in your car, and that smell can be given out through the AC. Whenever you sense an electrical burning smell, it is best to turn off your car and get it towed to the nearest mechanic, as this situation can be dangerous.

4. Fuel Leakage

If you are smelling some sort of fuel from the AC, then that signifies a gas leak. A fuel leak can be happening in several parts of your AC, including fuel lines, fuel tank, fuel carburetor, or fuel injectors. Such a leak can give out a very strong and unpleasant odor, and it is a great risk to your safety. The AC in your car majorly relies on the air flowing through the evaporator into the interior of the car. When there is a fuel leak, the smell can be picked up by the air and spread throughout the car interiors.

5. Clogged Air Ducts and Vents

The AC’s ducts or vents can be clogged with debris, dirt, or dust. Even this can lead to an unpleasant odor coming out from your AC. This clogging can lead to bacteria, fungal, and even mold build up which is the major culprit behind the dirty feet smell coming from your car’s AC.

6. Skunk

We all know how skunks give out a very unpleasant and unbearable odor. If you are smelling something similar to a skunk spray inside your car, it can be due to a gas leak. When this happens, you must immediately take your car to a professional as this situation is a safety hazard.

How to Fix the Car AC Smell?

Here are a Few Things You Can Try to Fix the Car AC Smell.

  • Thoroughly clean and carefully disinfect your car AC’s evaporator using a specialized evaporator liquid or foam.
  • Change the cabin air filter once the evaporator is cleaned.
  • Check if the durian tube in your car is working properly by ensuring that the water is dripping down when the car AC is running.
  • Before ending your car trip, allow the blower to dry out any remaining moisture for 10 minutes.

How to Maintain an AC in a Car?

As you might have noticed above, with proper maintenance, many of the issues in your car’s AC can be eliminated, including the dirty feet smell from the AC. Here are a few things you can do to maintain the AC in your car.

  • Change AC Filter: You need to ensure that the AC filter is being changed regularly. It is a good idea to replace the AC filter once every 6 months. When the AC filter is clogged, it creates an extra strain on the AC blowers, which can drastically reduce the AC’s lifespan and efficiency. If you are apprehensive about changing the AC filter regularly, try to clean it regularly.
  • Run Defrost System: Moisture is a major cause of bacteria, mold, and fungal build-up. Remember to run the defrost system to ensure minimum to no moisture left after the AC runs its cycle. Let it run for about 15 minutes, reducing the possibility of mold buildup
  • Check Coolant: You also need to ensure the pressure maintained is ideal for the circulating coolant. Coolant in the AC passes through hoses, and when there is damage in these hoses, it can leak and run out before time. You can expect your car’s AC to function effectively with no coolant. When the hoses get clogged, the pressure on the coolant can increase significantly, which is, again, undesirable.
  • Check Evaporator Coil: Whenever you conduct a routine maintenance check, ensure that you see what state the evaporator coil is in. If the evaporator coil is damaged, make sure that you replace it with a new one so that your car’s AC can run efficiently.
  • Check Evaporator Fins: If you notice that your car’s AC is not functioning properly, you must also look at the evaporator fins. Sometimes the condenser fins can be bent, which may cause the AC not to function as it should. You can easily straighten the fins out to get your AC working properly quickly.

Car AC – FAQs

1. Why does my car suddenly smell like feet?

Ans: If your car suddenly smells like feet, there may be some issue with the AC. There may likely be moisture building up in the AC instead of getting drained out. This can cause mold and mildew to grow and thrive, creating an unpleasant odor.

2. How often should car AC evaporator coils be cleaned?

Ans: You must clean the AC evaporator coil at least once a year, along with a tune-up every season.

3. Is the AC system responsible for all car odors?

Ans: No, not all car odors are caused due to the AC system in your car. The unpleasant odor may result from fuel leaks, engine problems, or other interior issues. You must identify the source of the odor as soon as possible because some situations can be life-threatening.

4. Can a clogged drain tube cause the AC to smell like feet?

Ans: A clogged drain tube can cause the AC to smell like feet. When the drain tube gets clogged, it can cause moisture to build up in the AC system, creating an environment perfect for mold and mildew growth, creating a musty odor.

5. Can a malfunctioning AC compressor cause a foul odor in the car’s AC system?

Ans: A malfunctioning AC compressor will not directly cause a foul odor in your car, but it can definitely impact the AC’s overall performance, leading to moisture buildup. This can cause mildew and mold to grow and produce odors.


When the AC system in your car malfunctions, it can cause several types of unpleasant smells in the car interiors. The possible smells and their fixes are mentioned in detail above. When you can pinpoint the exact type of smell, finding out its source becomes easier and this makes the process of eliminating the smell much faster. Whenever you notice an unusual smell coming from your car’s AC, it is crucial that you get to the crux of the matter as soon as you can, as some smells can be an indication of something dangerous which might need your immediate attention.

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