Heating and air conditioning installation for a motor vehicle with flow of filtered air

The installation has an electrostatic filtration system (30) for treating particles, and a plasma catalysis system (40) for treating gas pollutants, odors and micro-organisms. The system (30) has an ionizer for ionizing particles before they are collected by a particle filter. The system (30) is placed upstream of the system (40) in a manner to limit choking of the system (40).