Categories: A/C SystemsHow to

Removing and Preventing Musty Odor in Vehicles AC

That mildew smell coming from the air conditioning could be caused by fungus growth in the cars air conditioning system. As the odor permeates through the interior of the car it may also be absorbed in the seats and carpeting of the car. Knowing what causes the mildew odor will help to prevent the smell from reoccurring.

What Causes That Musty Car Air Conditioning Smell?

The real simple answer is water condensation. As the air conditioning systems are being used it builds up water condensation that can settle in the cars evaporator core housing. The evaporator core is similar to the coils on the back of some older refrigerators.

It’s surrounded by a black case (housing) and as the evaporator drips water from condensation it settles in the housing and becomes stagnated, causing a mildew type odor.

How to Get Rid of the Cars Musty Air Conditioning Smell

Many auto repair shops have a service that will get rid of the foul odor. Some auto parts stores also have a kit available that can rid the car of the musty smell. There are some pressurized cans of foam out there that foams up inside the evaporator core housing and scrubs the inside of the housing and core. This method requires a hole to be punched in the evaporator core housing. The foam works its magic and then dissolves and leaks back out of hole punched in the housing.

A better method is to have a professional auto technician to use a sonic system that actually creates a fog inside the car. The car’s air intake in the ac system sucks in the fog and the fog is distributed throughout the ac system killing the bacteria. This type of system also soaks into the car’s interior carpeting and seats and leaves the interior smelling fresh and clean.

Preventing Mildew Odors From the Cars AC System

Since the smell is caused by condensation, the best way to prevent the smell from reoccurring is to make sure the condensation dries out. The car’s ac controls (on the dash) allows for closed and open circulation of the vents. Some cars have a closed/open circulation button on the ac controls. For cars that do not have a closed/open circulation button, max ac is closed circulation and normal ac is open circulation.

When the ac is in closed circulation mode (or max air), the air is circulated inside the vehicle. In normal ac mode, air from the outside of the vehicle is circulated through the ac system. When the car’s engine is turned off and left in closed circulation (max air), the vent doors stay closed allowing the condensation to stagnate.

Steps to Help Dry Out the Water Condensation

  • A few minutes before turning the car’s engine off, set air conditioning controls to open circulation (circulation button or normal air mode).
  • Turn the car’s engine off and leave air conditioning controls in open circulation mode.
  • Before restarting the car’s engine turn air conditioner off so the air compressor doesn’t activate while starting the car.
  • When turning on the air conditioner, leave it on outside circulation for a few minutes Leave the air on open circulation as much as possible while driving.

There are times when preventing the outside air from entering the cabin of the vehicle is beneficial, especially if there are contaminants in the outside air like dust, smoke, or smog. Never allowing outside air from entering the air conditioning system will more than likely result in that nasty musty smell.

Serving the air conditioning system as routine vehicle maintenance will also help the smell from reoccurring. Following these simple instructions will help make the driving experience that much more enjoyable.

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I am Derek Patrowsky, editor of AutoSportCatalog.com. I have over 17 years of experience in the automotive service industry and am part owner of a service facility in his hometown. Together with other writers, I hope this website will help you with your auto repair needs making better decisions when it comes to your vehicle.

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