Why does the car air conditioner emit an unpleasant odor when turned on?

[SamanthaLynn]

When a car air conditioner emits an unpleasant odor upon being turned on, it is usually caused by mold growth in the evaporator and ventilation ducts. As air enters the car, the evaporator cools or heats it, blowing out warm or cold air through the vents. During this process, bacteria, dust, insect remains, and other debris can accumulate in the evaporator and ventilation ducts. Over time, this buildup leads to an unpleasant odor when the air conditioner is in use. Below are some solutions to address the odor issue in car air conditioners: 1. Inspect the air conditioner ducts: Choose an open, sunny area, open the car doors, and turn on the natural air setting. Set the system to external circulation at maximum power for 5–6 minutes to blow out the accumulated dust. 2. Check the air filter: The air filter should generally be replaced once a year. If the car is frequently exposed to sandstorms or other harsh weather conditions, it is advisable to replace the filter every few months. Cleaning the air filter is not recommended, as it can enlarge the filter pores, significantly reducing its filtration efficiency.