Why Does My Car Air Conditioner Smell: Weather Related Smells Explained | Sun Devil Auto

The Weather and Your Car

Pee-yew! What is that smell? It’s your car. How does a car go from that wonderful new car smell to a sudden moldy, mildew, or gasoline smell? There are several factors that may contribute to the smells that your car emits over time such as weather and normal wear and tear. In order to determine what is causing the bad smell, you’ll first need to figure out what is responsible for the offensive odor.

Smell: Musty, Mildew When Using Air Conditioning

car smells in the weather As cars age, air conditioning systems begin to smell and grow bacteria, mold, fungi, and other microorganisms. The area affected is most often found behind the dash on the evaporator. When your car air conditioner smells and lets out a pungent mildew-like odor, but otherwise seems fine when not in use, you can be sure your car has some sort of growth or contaminant causing the smell. While it is certainly unpleasant, it’s a common issue affecting many cars, especially in areas of the country where humidity is high. There are some preventative measures you can do to help discourage the growth of mold or bacteria in your AC. Lack of using air conditioning is a contributor to this common problem. Run your air conditioner, defroster, or heater, even when the weather is comfortable, for a few minutes every time you drive to allow your system to fully cycle. Avoid using the MAX AC option all the time when driving. This causes excess water to drip in the unit. Warm, damp, and humidity are the perfect conditions for mold to grow.

Resolution: Take your vehicle to a trusted auto repair facility. A technician will inspect the system to ensure the air conditioning drain tube is not clogged. The technician will then use an anti-bacterial cleanser to destroy any growing bacteria behind the dashboard and finally, inject a treatment solution into the AC case, turn the air conditioning off and let the fan run to let any moisture remaining on the coils evaporate.

Smell: Musty, Mildew In Cabin

This smell is something that cannot be eliminated with a simple spray on freshener or a little tree hanging from the rearview mirror. So, what is responsible for the odor? A dirty air filter can be the culprit. Just like your home’s air filter, your car collects dirt, dust mites, pollutants, and stagnant water. A dirty air filter may cause pollutants to enter the cabin area along with an unpleasant odor. Mildew in the passenger area could also be caused by a buildup of moisture or humidity. Locating the source of the smell is key. Check the spare tire storage and trunk areas along with the carpeting and floor mats. Look for any signs of leaks. Also, have the air conditioning evaporator drain tube checked. A clogged evaporator tube may cause the air conditioning unit to fill up with water and leak or cause stagnant water to pool within the vehicle.

Resolution: Replace the cabin air filter (if applicable) and air filters every three to six months. If your air filters look relatively clean, search for moist areas within the vehicle. Remove all floor mats and carpeting, if possible, and hang to dry in direct sunlight. Once the affected area is located, wipe dry and scrub off any mildew or mold and dry completely. Sprinkle baking soda on upholstered areas and allow the vehicle to sit for 24 hours.

Smell: Gasoline While Parked

You should never be able to smell gasoline coming from your vehicle. If you do, something is wrong. If you notice your car smells like gas inside the cabin area, take the vehicle to a trusted technician right away. Gas fumes can cause headaches, dizziness, and longtime exposure can cause brain damage. The smell of gasoline can be caused by several different items within the fuel system. The most common causes are:

  • Gas Cap – Damaged gas caps can release fumes and trigger the check engine light to illuminate.
  • A leaking fuel pressure regulator – A leak in the system causes the exhaust to seep into the ventilation system, forcing gas fumes to enter the passenger area.
  • Fuel lines – Fuel lines connect the engine to the fuel tank. Because of their position, located under the hood of the car, fuel lines are vulnerable to road debris, road conditions, and wear with age.
  • Fuel Injection Line – Leaks within this component encourage higher pressure along the fuel lines. Weak fittings can cause fuel to leak out at different sections.
  • Injector – Fuel injectors are fitted with rubber seals that eventually crack due to age and dryness.
  • Fuel Tank – A punctured or damaged fuel tank can release gas fumes and cause fuel to leak out of the vehicle.

Resolution: Replace the gas cap, especially if the check engine light has come on. It’s important to note that the check engine light will also light up in the event that gas fumes are escaping through the emission system. However, not all portions of the fuel system are emission related. Check under the car for any noticeable puddles and have any leaks addressed by a trusted auto repair center like Sun Devil Auto.