Bad smell coming out of the air vents when running air

Bad smell coming out of the air vents when running air

My car has 14000 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :
Hi there, thanks for writing in. I’d be happy to help. This is often a common issue with a bad cabin filter. This is a paper element that works similarly to an air filter for your engine, but filters the air that comes into the car’s cabin. When this is dirty or has picked up something into one of the car vents, this can emit an odor into the cab. I would recommend having this changed at your next service as it will not harm the car in any way.

Here at YourMechanic, we can have a technician come to your home or office to perform your next oil and filter service for you.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

Dusty and Dirty

Air filters collect dust mites, dirt, and pollutants, the buildup of which can cause an unpleasant smell from your vents when you use the AC or the heater. This putrid smell can be avoided by replacing air filters every 10,000 to 15,000 miles as recommended by the vehicle manufacturer.

The reason AC filters become smelly is because when dirt gets trapped on it, it can cause spores to grow and the odor gets trapped or passed on to the air. Dirt builds up in the filters also restricting airflow, trapping more moisture in.
Sort of like an old gym bag, this smell results from dust and bacteria build-up in the AC ductwork caused by a dirty cabin filter. This is the leading cause of bad AC smells. Replacing the cabin air filter is a quick, inexpensive fix any DIYer can do.
If your air filter is new and clean, another DIY solution is to put a bit of baking soda in your air ducts. When we say that, we literally mean, put a dish or the whole box of baking soda in your air duct and let it sit there. (The same way that you would place a box of baking soda in an offensive-smelling fridge.)
If your car emits a rotten egg smell, there might be a problem with the catalytic converter, fuel pressure regulator, fuel filter, or even the old transmission fluid. Whatever the cause, if you get the rotten egg smell in your car, take your vehicle to the mechanic as soon as possible and resolve this problem.
Burning Rubber Smell in Car

The smell of burning rubber in your car can indicate that a rubber hose or belt under the hood has loosened. When this happens, these parts can move around and come into contact with hot engine parts—hence the burning rubber smell.

Replace or Wash Air Filters

If mold has accumulated on air filters, the best thing you can do is replace them. If your AC has reusable filters, you can thoroughly wash them with warm and soapy water. To kill the bacteria, rinse them with diluted bleach.

Mildew is the most common culprit when an AC smells bad. If you smell moldy air coming from your AC vents, mold or fungus are growing in or around your AC unit and can sometimes make their way into the ductwork itself.
Air purifiers are known to be great at removing dust, pollen and other allergens from the air, but do air purifiers remove odors and smells? Yes, some air purifiers can actually help remove various smells, such as smoke and pet odors.
Air purifiers are known to be great at removing dust, pollen and other allergens from the air, but do air purifiers remove odors and smells? Yes, some air purifiers can actually help remove various smells, such as smoke and pet odors.
It usually has a clean smell, almost like the smell you would experience after a thunderstorm or in a chlorine-treated swimming pool. Ozone is a byproduct of some air purifiers, and this might be why you have that disturbing smell in your house.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Bad smell coming out of the air vents when running air
ANSWER : Hi there, thanks for writing in. I’d be happy to help. This is often a common issue with a bad cabin filter. This is a paper element that works similarly to an air filter for your engine, but filters the air that comes into the car’s cabin. When this is dirty or has picked up something into one of the car vents, this can emit an odor into the cab. I would recommend having this changed at your next service as it will not harm the car in any way.

Here at YourMechanic, we can have a technician come to your home or office to perform your next oil and filter service for you.

Sour, stale smell coming from air vents
ANSWER : This is most likely a cabin filter that needs to be changed. Your car is equipped with an air filtration system that works similarly to your engine’s air filter in that it filters the outside air as it flows into the cabin of the car when you have the vents open. Over time this filter will get dirty just as your engine air filter does and, in some cases as you describe, it will emit an odor or smell that is filtered into the cabin when you turn on the vent air.

I would recommend having an expert mechanic, such as one from YourMechanic, come to your location to replace the cabin air filter for you.

Cold mist/smoke like air comes out of the air vents when cold air is on.
ANSWER : If you are using regular outside air a/c instead of recirculated air you may be getting a large amount of outside air humidity and can cause a mist to come out of the a/c vents. You should make sure the a/c evaporator drain is cleared and drains freely or the water in the a/c cannot drain fast enough and the blower will pick up the water and blow it out the vents.

Soap smell coming out of car after cabin change. Changed filter the the smell is still coming. What to do about this strong smell?
ANSWER : Hi There,
As you know, your car has a cabin filter that serves to filter the air that is introduced to the cabin inside the vehicle. The best way to remove your cars interior ac odor is to use a cleaner that uses enzymes. Enzymes in cleaners kill odors at the source and completely kill the smelly substance material and therefore stopping the a bad smell. To get rid of the smell, try the following: First turn on the ac to full, make sure the “recirculate” button is not on, spray a large amount of cleaner with odor killing enzymes into the EXTERIOR air intakes that are located just below the windshield wipers, let the car run for about 10 minutes with the ac on, after 10 minutes turn off ac and spray the cleaner into the ac vents on the INSIDE of your car. After doing all this, let the car sit for 20 minutes turned off and windows rolled up. Then repeat if the smell is still in the car. By doing this you are killing the bacteria or mold in the car ac vent ducts and also the evaporator mold that may be present.

air conditioner not blowing air from dash vents, but blowing air from side vents
ANSWER : A few different items can cause the air to not blow out of the dash vents. The most common are a blend door or a control switch. The best method for the AC diagnosis feature can be found in the vehicles owners manual. I recommend having your AC checked by a qualified technician, such as one from YourMechanic, to have the problem diagnosed and repaired correctly.

Air conditioning smells bad when car enables autostop feature
ANSWER : Your vehicle is new enough that I couldn’t find much information on the air conditioning system. I’m guessing your vehicle probably has a dual scroll AC compressor in which one scroll is driven off the engine and the other is electric. In order to prevent lack of cooling at idle, this design is used in hybrids and vehicle with start/stop ability. So, the lack of cooling may be due to a problem with this system. The foul smell by be result of bacteria accumulating on the AC components. Replacing the cabin filter may help with this problem somewhat. I suggest you have a trained professional diagnose your vehicle firsthand to determine the exact cause of the smell.

Problem with AC/heater – 2005 Ford Explorer
ANSWER : Hello. The problems you describe with the front system may either be a faulty control switch or faulty vacuum motors for the air blend doors. The problem in the rear is likely the rear heater control valve, which regulates the flow of hot coolant to the rear heater core and air duct system. The clicking noise may be a broken vacuum motor for that valve (integrated in the valve).

I would recommend having a certified mechanic, such as one from YourMechanic, come to your location to perform an inspection of the heater and suggest the needed repairs.

My heater is blowing air through the driver side air vents but is blowing cold air through the passenger side and rear console ven
ANSWER : Hi there:

Climate controlled vehicles have multiple electrical relays that open and close vents to maintain the desired temperature. In some instances, these relays can wear out overtime. However, it’s also common for debris to clog up vents (especially side vents) which may restrict the flow of cool air. The best way to determine why your AC is not working efficiently, it might be best to have a professional mechanic complete a AC inspection; so they can pinpoint the source of your issues and recommend the right repairs.