The quality of the air inside the car is directly related to the ventilation and purification capabilities of the HVAC. To achieve air purification and improve air quality, air purification and improvement devices are necessary.

General car air filters can be divided into particle filters (which can filter dust in the air), carbon fiber filters are also called combined filters (which can filter harmful gases and odors in the air), and negative ion filters (in addition to having In addition to the filtering function, it also produces negative oxygen ions that are beneficial to the human body), vitamin C filter (in addition to the filtering function, the filter can also release vitamin C to help keep the skin moist), various aromatherapy filters, etc. , the first two are the most widely used. Generally, filters are required to be able to filter dust in the air, harmful gases such as CO, NO, HC, SO, odors such as HS, etc. Different types of filters are selected according to different users and different needs.

There are several positions of the filter in the HVAC. No matter which placement method makes the air entering the HVAC more uniform, it can shield and reduce the noise.
1. The filter is set upstream of the HVAC, at the air intake of the car
2. The filter is placed between the HVAC blower and the air inlet
3. The filter is set around the blower

4. The filter is set between the blower and the evaporator (the bottom of the filter must be higher than the bottom of the evaporator, otherwise it will be soaked by condensed water)

Vehicle air quality control needs to start from three aspects:
A. Prevent pollution from outside the car from entering the car (using air quality sensors and fast-responsive intake air door micromotors)
B. Prevention of HVAC bacteria generation (filters with antimicrobial media or electronic filters)
C. Purification of air in the car