Small spaces between the slits in your car's air conditioning can be difficult to clean with a cloth. However, foam brushes make the job faster and easier. Clean the air conditioning vents once a month, every two months or more often if they get dusty. If you notice a musty smell when you turn on the air conditioner, clean the ventilation system with a disinfectant spray cleaner. To prevent mold from forming, periodically dry the ventilation system by turning the fan on full power with the air conditioner off, and be sure to remove any debris left on the outside of the air intakes.
Steps
Method 1 of 3: Clean the crevices with a foam brush

Step 1. Buy a set of foam brushes
These brushes are perfect for reaching the spaces between the air conditioning vents. These brushes are inexpensive and can be found at home improvement stores, craft stores, or all-in-one-price stores. You can also buy them online.

Step 2. Create a homemade cleaner
Combine equal parts warm water and white vinegar. Try a lemon-scented cleansing vinegar if the smell of pure vinegar bothers you. If you can't find lemon-scented vinegar, add a tablespoon of lemon juice to your household cleaner.

Step 3. Tuck the foam brush between each slit
Dip a foam brush into the cleaner and press it between the vents to remove dust and dirt. Rinse the brush as needed to remove accumulated debris, or just use another brush. To finish, clean the crevices with a dry brush if there are any cleaner residue left.

Step 4. Rinse and dry the used brushes
Wash the brushes you used with warm water and a little dish soap. Squeeze and rinse well to remove excess soap. Let them dry, put them in a plastic bag and store them in the glove compartment for reuse.
Method 2 of 3: Clean the air conditioning vent system

Step 1. Replace the car's cabin filter
Most newer car models have an easy-to-change air filter that you can access from the cabin. You should read the instructions in the car's manual to find out how to remove and replace it.
- On many newer models, including Honda's and Toyota's, you must lower the glove box first by removing the tabs that support it. You must remove the screws that hold the panel in place and are located just below the glove compartment. On GM sedan models, the filter is located in a box under the dash on the driver's side.
- After you've lowered the glove box or removed the panel just below it, find the clip that secures the air filter cover. Squeeze to release and remove the cover.
- Remove the old filter from its place and replace it with the new one.
- You should change the cabin filter once a year. Consider changing it more often if you live in a dense urban area or in a dusty environment.

Step 2. Clear and spray the air intake slits
The air intakes are located on the outside of the car, around the windshield. Use a broom or brush to remove dry leaves or any other accumulated debris. Spray the enzymatic cleaner inside the slits.
Enzyme disinfectants help eliminate mold or mildew growing in the ventilation system, while flavorings only act as perfume. Choose a cleaner that says "fights mold and moisture," "disinfectant," or "antibacterial," as these sprays contain an enzyme

Step 3. Spray all crevices with disinfectant cleaner
Close the doors and windows of the car. Make sure the car is off and the keys are not in. Spray the entire interior of the car's crevices with the enzymatic cleaner.
Read your car manual to make sure you find all the air conditioning cracks

Step 4. Start the car and set the air conditioning to full blast
After you've sprayed all the slits, start the car. Turn the air conditioning and fan on high. After ten minutes, turn off the air conditioner, open the doors, and leave the fan on for another five minutes.

Step 5. Take your car in for service
If the smell continues, you need to service the air conditioner. If the moldy smell doesn't go away, ask your mechanic or the agency about replacing the main vaporizer. Other odors, such as gasoline or antifreeze, can mean there are leaks in the system.
The cost of the pieces ranges from $ 300 to $ 2000, depending on whether you are going to wash or change them
Method 3 of 3: Prevent Mold Growth

Step 1. Turn off the air conditioning before reaching your destination
Get in the habit of turning off the air conditioning and leaving the fan on for a few minutes before reaching your destination. Do this three to five minutes before turning off the engine. Leaving the fan on for a few minutes after turning off the air conditioner helps to dry out the ventilation system and this prevents mold from forming.

Step 2. Remove leaves and other debris from the air intakes
Never let things accumulate in the air conditioning inlets. Remove the trash every week or more often if necessary. Leaves and other debris that accumulate on the windshield cause mold to grow in the air conditioning system.

Step 3. Regularly turn on the fan with the air conditioner off
Every two to three months, choose a warm, dry day to clean the vents in the air conditioner with the fan. Open all the car doors, make sure the air conditioning is off, and turn the fan on to full power. Drying crevices with this technique usually prevents mold from forming.