What Causes Bad Odor Inside a Car?
3 Answers
The causes of bad odor inside a car include odors from items in the car, air filter odors, and evaporator odors. Below are the reasons for bad odor inside a car: Odor caused by the air filter: When the air conditioning is turned on, a sour and musty smell blows out, but this condition usually improves after a while. In fact, this odor is a sign that the air filter needs to be replaced. The air conditioning system has been decomposed by bacteria, leading to mold, and replacing the air filter can alleviate the odor. Odor caused by the evaporator: If the odor persists even after replacing the air filter, this situation points directly to the evaporator. It is caused by mold inside the evaporator, and cleaning the evaporator and air conditioning ducts is necessary.
Back when I drove a taxi for ten years, I often encountered strange odors inexplicably wafting in the car. The most common issue was problems with the air conditioning system—moisture accumulated in the ducts during summer cooling, which easily led to mold growth, resulting in musty-smelling air blowing out. Then there were various food residues or spilled drinks left by passengers that weren’t cleaned properly, like milk tea seeping into the carpet, which was especially hard to deodorize. Once, a passenger forgot fresh groceries in the trunk, causing a foul smell. A car wash owner taught me that exposing the interior to sunlight, ventilating it, and wiping it down with baking soda water worked wonders. Another easily overlooked spot was small animal carcasses getting stuck in the hood gaps—you had to check the corners of the engine bay. Regularly replacing the cabin air filter was crucial. Once, after switching to an activated carbon filter, the odors disappeared completely.
As a mom who frequently shuttles kids around, I'm particularly sensitive to odors inside the car. Once, baby cookie crumbs fell into the seat crevices unnoticed and turned sour and smelly the next day, so now I clean those gaps weekly. When a friend's child got carsick and vomited, incomplete cleaning led to bacterial growth and unpleasant odors. The most noticeable smell I encounter in parking lots is the lingering tobacco stench from smokers, as nicotine seeps into the headliner fabric. I recommend placing bamboo charcoal bags under child seats—these physical adsorbents are safer than chemical air fresheners. Last time, rainwater seeped through the sunroof seal and soaked the carpet, causing mildew that required professional dismantling and drying. Also, check if fallen leaves have accumulated and molded in the AC evaporator box, especially during spring-summer transitions when this issue most commonly occurs.
