1998 Buick Century Owner's Manual - Page 178

Backglass Antenna(If Equipped) Your AM-FM antenna is integrated with your rear window defogger, located in the rear window. Be sure that the inside surface of the rear window is not scratched and that the lines onthe glass are not damaged. If the inside surface is damaged, it could interfere with radio reception. Because this antenna is built into your rear window, there is a reduced risk of damage caused by car washes and vandals. If you choose to add a cellular telephone to your vehicle, and the antenna needs to be attached to the glass, be sure that you do not damage the grid lines for the AM-FM antenna. There is enough space between the lines to attach a cellular telephone antenna without interfering with radio reception. On cars equipped with the rear window defogger and built-in antenna, the defogger grid serves as a radio antenna. If you have this feature on your car, do not apply aftermarket glass tinting to the back glass. The metallic film in some tinting materials will interfere with or distort the incoming radio reception. Care must be taken when cleaning the rear window because breaks in the resistive material heating element will adversely affect radio performance and defogger performance. See your dealer for details. NOTICE: Do not try to clear frost or other material from the inside of the rear window with a razor blade or anything else that sharp. This may damage is the rear defogger grid and affect your radio's ability to pick up stations clearly. The repairs wouldn't be covered by your warranty. 3-36