Weatherstripping around a car's door frame is intended to keep the elements out when the doors are shut. As the door seal ages, it can become brittle and unable to stop water and ice from entering the passenger compartment during bad weather. You can install a seal on a car door yourself and correct the problem before the elements force you to make the fix.
Open the car door and inspect the existing door seal. Begin at one end and pinch the seal with your fingers and pull up. Find the anchor points for the old door seal and determine if it is glued or clipped or if screw fasteners hold it to the door frame. Use a razor to cut the seal away from the frame for glued applications, unscrew the fasteners for screw anchors or pull up on the seal with pliers where it clips into existing drilled holes in the door frame.
Clean the door frame where the old door seal was attached. Clips that hold the new seal should be sanded lightly with Emery cloth. Door seals that use push clips should have holes that are clear of debris. Use a drill and bit to clean these holes. Clean the door frame down to the metal where the old door seal was laid if the old seal was glued to the frame.
Stretch the new door seal around the door frame for a proper measurement. If the new door seal has push pins or slides that need to be mated with the holes or slides on the car door frame, then you must adjust the position of the new seal to match the anchor points on the frame. For glue-type door seals, you just need to cut and measure to the correct length.
Secure the new car door seal to the car door frame. If you are screwing the new seal in place, use the existing anchor points to fasten the door seal to the door. For a seal using fasteners, push the new fasteners into the existing holes. Glued seals will require you to spread an even layer of glued along the outside of the door frame and then centre the seal and press firmly to affix the door seal to the frame. Glue should be allowed to dry at least six hours before closing the door, preferably 24.
Clean a painted door frame with a wire brush before gluing a new door seal. If you choose to replace another type of seal with a glue-type, make sure you remove all the paint from the metal first. Make sure you have the door seal turned the right way. Flip the seal around and look at the angle. Close the door if you're not sure, and check to see that the door seal is aligned correctly before securing it to the frame.
It is possible for you to damage wiring inside the door frame if you drill into it without first knowing where the wiring is located. Installing a different style of door seal can result in damage when this occurs.