To change the cabin air filter on a 2000 Buick Century or similar vehicle, first with the hood down, turn the ignition on, turn the wipers on, turn the ignition off with the wipers straight up.
Lift the hood and go to the passenger side of the car. Remove the retainer next to the passenger side wiper arm. It has a threaded push pin that needs to be backed out and then the whole retainer can be removed.
Do the same thing to the retainer in the corner next to the fender. You will also need to lift the washer hose from the top of the cover assembly.
There is a larger threaded retainer in between the other two that also needs to be removed. Just remove like any screw.
Pull the seal of the front edge of the cover and metal base. Lift the cover to access the filter. There is a pull strap on the front edge of the filter that can be used to lift and pull the filter out of the car.
Make sure your new filter is the correct design.
Install new filter. I have found that the new filter will have to be bent into a slight “C” shape in order for it to go into the slot. You may have to work with it some to get it into place. Do not dislodge the plastic holder for the filter as you may develop water leaks. On some vehicles there is a water deflector that goes over the filter. This car had a rubber edge seal that was out of position. You can see the shadow of where it was mounted on the leading edge of the white metal in the picture below.
You can see the seal back in place in the following picture.