Automobile maintenance

Reasons Why Car AC Smell

Reasons Why Car AC Smell
Written by Autofot
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If your car’s AC smells like rotten eggs, mildew, plastic, or gas, there could be a problem with the air conditioning system. This article will help you understand why your car AC smells and what causes these odors in the first place.

AC Smells Like Rotten Eggs

You’ve probably smelled it before. A rotten egg smell is a sign of a refrigerant leak. It can be caused by a leak in the system, but there are also other causes.

  • Leaks in the compressor shaft seal or oil seal can cause this smell. The compressor is what pumps the refrigerant into your car’s air conditioner, so if it has any leaks, that’ll be where you find them most often. If the leak isn’t too severe and you haven’t noticed any drips under your car when it rains, then there’s nothing to worry about immediately—you can take care of this problem once you have time for an oil change or when you’re having your next service appointment at a mechanic shop near me.
  • If there isn’t enough refrigerant in your AC unit as well as leaks from seals (like mentioned above), then both problems will need to be fixed before getting rid of that rotten egg smell.
  • If hot air comes out of vents when you turn on your AC unit despite being set at full-blast cold air mode then that could mean there’s not enough refrigerant left inside either.

The smell of sulfur or rotten eggs is a sign that the refrigerant in your vehicle’s air conditioning system has leaked.

If you smell sulfur or rotten eggs, it’s a sign that your vehicle’s air conditioning system has leaked refrigerant. Refrigerant is a gas, and when it leaks from the system it can cause the gas to evaporate. If this occurs, you may notice an odor like sulfur or rotten eggs as well as white dust particles on your car’s vents and/or inside of its AC unit.

The odor is not harmful to humans, but if left unchecked over time it could result in reduced cooling efficiency for both heating and cooling modes of operation.

AC smells like mildew

Mildew is a type of fungus that can grow in damp areas. If you have mildew growing inside your car, it can smell like rotting leaves or even a wet towel left in the washer too long. Mildew can grow in the air conditioning system, cabin or engine bay.

If you notice an acrid smell coming from your vents, it may be because there are particles of mildew inside your air conditioning system ducts that need to be removed and cleaned thoroughly.

This is a sign that moisture in the system has built up.

  • Moisture buildup can occur in the system, which is a sign that there’s an issue with your vehicle. The excess moisture could be caused by a leak somewhere within the air conditioning system. This can cause damage to other components and cause problems with your air conditioner as well.
  • A clogged cabin filter may be causing this smell and should be replaced immediately to prevent further damage from occurring
  • The AC smells like burnt plastic or rubber

If the AC smells like burnt plastic or rubber, it’s a sign that there is a refrigerant leak in the system. If there is a leak, the refrigerant can leak out of the system and into the engine compartment, where it can cause damage to your engine. The leak might be caused by a faulty seal or a ruptured line.

If you’re noticing this smell after driving your car for some time, it could be indicative of an issue with your dash vents—particularly if only one vent is emitting this odor and not all three at once.

This can be caused by a failing compressor clutch, which leads to belt slippage and excessive pressure on the serpentine belt. Belt slippage is a sign of a failing compressor clutch.

Here’s how it works: The air conditioner’s compressor acts as both an engine and a pump, compressing refrigerant vapor into liquid form so it can travel through your car’s cooling system. As the refrigerant passes through various parts of the system—like your condenser and evaporator—it cools down until it reaches its final destination: your cabin air-conditioning vents.

But if there’s any sort of problem with this process, like if you have an old or faulty compressor clutch or belt slippage issue (where one side of the serpentine belt slips over another), then your AC won’t work properly anymore!

AC smells like gas or rotten meat

If your car’s air conditioner smells like rotten meat or gasoline, it’s a sign that there is a refrigerant leak in the system. The smell is caused by the refrigerant leaking out of the system and being released into the air. A small amount of this gas is toxic to humans and animals, so if you smell it inside your car, it could make you sick. If you smell something similar while driving down the road, pull over immediately and call for help; the leak may be serious enough that you need to evacuate your vehicle before it starts leaking more dangerously! Read Also: Why is my AC Blowing Hot Air In my Car

This is a sign that there is a refrigerant leak in the system.

If there is a refrigerant leak, it can cause your air conditioning system to overheat or freeze up. If this happens, you will notice that your car’s air conditioner isn’t functioning properly and that the interior of your vehicle feels warmer than usual. In addition to these problems, you may also notice that your car’s AC smells bad.

The smell should be relatively easy to diagnose: if there’s a bad odor coming from inside of your vehicle when it’s running, then this may indicate an issue with the refrigerant leak in one of its systems. In some cases where a leak is present but not causing any obvious symptoms (for example: no leaking fluid or moldy spots on any part of it), then it might be difficult for someone without experience working with AC systems under normal conditions to figure out exactly what happened here

There are many reasons why your car ac might smell

Your car’s air conditioning can smell like a variety of things when it’s in need of repair. The most common issue is mold, which is often caused by a blocked drain or clogged condenser. If your car’s AC smells like mildew and you notice that the vents are blowing warm air, chances are good that there’s a problem with your A/C system. Other common smells include gas, burning rubber and plastic, ammonia-like odors, as well as smoke coming from the vents.

Read More: Tips on How Much to Fix AC in a Car

If you’ve noticed one of these scents coming from your AC vents and have decided to investigate further on your own before taking it into an auto shop for servicing (we recommend doing this!), here are some tips for testing out whether or not the smell is coming from inside your vehicle:


The smell of your car’s air conditioner is not something you want to ignore. The smell can be a sign of a serious problem with the system. If you notice that your car’s AC smells, have it checked out by a professional technician as soon as possible.

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About the author


Autofot is a website that blogs on the importance of taking good care of our automobiles. Little things that are ignored matter the most, hence we try to educate car owners and other different auto owners on how to go about taking care of their cars with little or no cost.

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