Why does the car air conditioner emit a foul odor when turned on?

[LaBrielle]

The reason why the car air conditioner emits a foul odor when turned on is: mold growth in the evaporator box and ventilation ducts. Air entering the car is cooled or heated by passing through the evaporator box, and then blown out as warm or cool air through the vents. During use, bacteria, dust, and even insect remains inevitably enter the evaporator box and ventilation ducts. Over time, an odor will appear when the air conditioner is in use. Solution to the car air conditioner odor: replace the air filter. Generally, it should be replaced once a year. If sandstorms or other severe weather conditions occur frequently, it may be necessary to replace it every few months. If the air filter is only superficially dirty, it can be simply blown clean. However, if it is already very dirty, cleaning is not recommended, as it can cause the filter pores to enlarge, significantly reducing the filtration effect.