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Why Does My Car Air Conditioner Smell

Sheetal Mandora
There can numerous, unknown reasons why the car aid conditioner is smelling. Read the story to find out exactly why is it so, and what can you do to get rid of the smell.
The issue crops up when the fan is on and you can instantly notice that musty or mildew odor. It's definitely different from the new-car smell and can really leave you frustrated. And when you get that weird smell coming out of the vents, you can't really let it go unchecked.
It is a sure shot evidence to something going wrong with the system. Often times, it is due to growth of fungus in your car's air conditioning system. The worst part is that when this smell spreads throughout the car's interior and gets absorbed in the seats and carpeting.

Reasons Behind Musty Smell from Car Air Conditioning

There's a simple reason - water condensation. When the air conditioning system is on, water condensation develops and settles in the car's evaporator core housing. Your car's evaporator core housing is like an old refrigerator coil.
The housing is surrounded with a black case and once water starts to drip from the evaporator due to condensation, it settles inside it. Water collects there and that's when a car air conditioner smells bad.

Remedies that Remove Musty Smell from Car Air Conditioning

The first thing you can do is take your car to any auto repair shop that can help you get rid of the musky odor. There are also kits available at these shops which you can purchase to do the same. You can use pressurized foam cans that can be sprayed inside the evaporator core housing.
It cleans the inside of the housing and the core completely. To use the foam cans, you'll have to drill a hole inside the housing. Once the foam has completed its job, it will dissolve and leak out of the hole you made.
For thoroughly getting rid of that smell, get your car to any professional auto technician. They use a sonic system which creates fog inside the car. The air conditioning system absorbs this fog which distributes itself all around the system and kills the bacteria. Along with the air conditioning system, even the carpeting and seats absorb this fog.

Preventing Musty Smell from Returning

Since condensation is the main culprit here, you need to assure that it doesn't reoccur and the condensation is dried out. On the dashboard where your car's air conditioning controls are, you will find a button that allows "closed" or "open" circulation of the vents.
Use the controls if your car has the button, and for those cars that don't have one, if you keep "maximum" air conditioning, the circulation will be closed and for "normal" air conditioning, the circulation will be open.
And since our aim is to dry out the water condensation, let's take a look at fixing car air conditioning.
  • At least 4―5 minutes before you turn off the car's engine, keep the air conditioner's button at "open". This will provide a good ventilation to the entire car and system.
  • After turning the car's engine off, you can leave the button on "open" mode. Again, this will leave the car ventilated throughout the night/day and won't form that musky smell again.
  • In the morning, turn the system off before you start the engine. This way the air compressor won't activate itself while the car is turned on.
  • Once you are ready to turn the air conditioner back on, let it stay at "open" mode as often and as much as possible while you drive. Trust me, if you follow these instructions, you won't have to worry about that smell ever again.
Due to various contaminants like dust, smog, and smoke, we try to keep the car's air conditioning ventilation at "closed". Although that's a good thing, but never letting the outside air enter the system will make your car air conditioner smell.
After following the steps mentioned, if you are unable to get rid of the smell, you should take your car to an auto repair shop for a thorough inspection. Perhaps they can find another cause that's making the smell to return.