To change the cabin air filter in your car, follow these steps:

1. Consult your owner's manual to determine the location of the cabin air filter in your car. In most cases, it is located behind the glove compartment.
2. Open the glove compartment and remove all items from the compartment. You may need to push in on the sides of the glove compartment to release it from the dashboard.
3. Locate the filter housing cover behind the glove compartment. Remove the clips or screws holding the cover in place
4. Remove the old cabin air filter from the housing. Pay attention to the direction of the airflow arrow indicated on the filter to ensure the new filter is installed correctly.
5. Vacuum the housing to remove any debris or dirt that may have accumulated.6. Install the new cabin air filter into the filter

You should replace your car's cabin air filter at regular intervals, which is typically every 12,000-15,000 miles or annually, depending on your driving habits and the car model. However, if you drive in areas with a lot of dust, dirt, or pollen, you may need to replace the cabin air filter more frequently. It is also a good idea to replace the cabin air filter if you notice reduced airflow through the HVAC system or if there is a musty or stale odor coming from the vents. Regular replacement of the cabin air filter can help improve the quality of the air inside your car and prolong the life of your HVAC system.