Your 2001 Ford Focus is equipped with a special air filter called the cabin air filter. The cabin air filter is important in maintaining the quality of the air within the vehicle: It eliminates dust particles, debris and allergens from the air before it enters the vehicle via the air vents. It is also important to keep the cabin air filter clean, as a dirty air filter can cause the vents to become clogged with dust and dirt, making your air conditioner or heating system work hard to regulate the vehicle temperature. Replace the cabin air filter regularly to maintain the air quality within the Ford Focus.
Turn the 2001 Ford Focus off and remove the ignition key--it's important that no air passes through the vents while the filter is being replaced.
Open the passenger side glove box. You may need the vehicle key to unlock the glove box. Remove the contents of the box to ensure easy access to the cabin filter.
Locate the screws that secure the air filter housing cover in place. They are located on the interior ceiling of the glove box, one in each corner. Use the appropriate screwdriver to remove the screws.
Remove the air filter housing cover by pulling it out of the glove box. You will now see the cabin air filter. Slide the cabin air filter out of the housing and discard it.
Install the replacement cabin air filter by sliding it between the retainer clips. This will ensure the filter is secured into the housing. Replace the housing cover. Replace each screw and tighten using the screwdriver. Place the contents back into the glove box and close the glove box door. If desired, lock the glove box with the vehicle key.