Why is there an odor when the car's external air circulation is turned on?
3 Answers
The reasons for odor when the air conditioning is turned on are as follows: 1. Accumulation of dust over prolonged use: After years of use, the indoor filter and internal copper plates of the air conditioning system can accumulate a certain amount of dust. When this accumulation reaches a certain level, it can produce an odor, which is then dispersed into the air when the air conditioning is turned on. 2. Long-term moisture inside the air conditioning system promotes mold growth: After cooling or heating, the indoor unit of the air conditioning system often retains moisture. If the air conditioning is turned off immediately without a drying or anti-mold function, this moisture remains inside, leading to mold growth over time and the natural production of a musty smell.
When there is an odor when the car's external air circulation is on, it is usually due to the accumulation of a large amount of dust, mold, or bacteria inside the air conditioning system. Especially after the rainy season or when the air conditioning hasn't been used for a long time, the evaporator and ducts become damp, leading to bacterial growth that produces a musty or sour smell. I have personally experienced this often during the high-humidity days of spring and autumn. The solution is simple: clean the filter once a month, purchase an air conditioning-specific cleaning spray from Taobao or an auto parts store, spray it into the air intake, wait a few minutes, and then turn on the fan. If the odor persists, it is recommended to visit a professional shop for a thorough disinfection of the ducts. Don’t overlook external factors either; inhaling exhaust fumes or industrial pollution during peak city traffic hours can also cause strange odors, so try to avoid highly polluted routes. Keeping the car interior clean and well-ventilated can prevent this issue, as a comfortable driving experience leads to a more pleasant mood.
If you encounter a foul smell when using the air recirculation mode, it's likely due to a dirty air filter or mold in the ducts. I often deal with this issue myself—replacing the filter is incredibly simple: order a new filter online, and removing the old one takes just minutes. Spray some antibacterial spray into the air vents to eliminate bacteria, and the smell will naturally disappear. The odor worsens in humid weather, so make it a habit to check every quarter. Don’t forget to clean the corners of the car mats and remove trash promptly to avoid dampness and mold. If the smell is severe, there might be a deeper blockage; a quick visit to the repair shop for a small fee can fix it. Protecting your respiratory health ensures a fresh and safe drive. Replacing the filter is low-cost but highly effective.
