The car ventilation fan primarily improves comfort by circulating air inside the cabin, removing moisture and odors, preventing window fogging, and assisting the air conditioning system in enhancing cooling or heating efficiency. It is typically driven by an electric motor and works through the car's air conditioning ducts to ensure proper air circulation and prevent mold growth. Common types include cabin air circulation fans, defogger fans, and AC ventilation fans. Regular cleaning and inspection are key to keeping the ventilation fan functioning properly.