Jetta turns on warm air (not air conditioning), which occasionally smells. What happened?

It is caused by long-term moisture in the filter screen or fan and mildew and deterioration inside. Please replace the filter. If there is still an odor, clean the fan, which will make a big move.

The main reason is that the external exhaust gas, the accumulated smell in the car, the fragrance placed, the sweat smell of people and the body odor will all enter the car. When the air conditioner is used, the smell will merge with the air when it meets the warm and humid evaporator surface, and the smell will evaporate when the air conditioner is used.

There are three ways to reduce odor:

First, turn off the air conditioner in advance when approaching the destination, and turn on the natural wind and external circulation;

Second, every time the car starts, it is necessary to open the window for ventilation;

Third, when there is an odor, disinfect the external circulation air duct with cleaning agent and replace the air conditioning filter element.