There is no need to replace an air conditioner filter in your car if you've already replaced the cabin air filter. The reason for this is because these are two names for the same air filter. Other names that car air conditioner filters are known by are micron air filters, cabin air purifiers, passenger compartment air filtration systems and cabin air dust filters. These filters should be changed every 12,000 to 15,000 thousand miles. They are usually located either under the dashboard on the passenger side, or right up against the cowl, under the hood, on the passenger side.