2003 Cadillac CTS Owner's Manual - Page 228

Using the rear window defogger will not cancel automatic climate control operation. Ventilation System NOTICE: Don't use a razor blade or something else sharp on the inside of the rear window. If you do, you could cut or damage the warming grid or the integrated rear window antenna, and the repairs wouldn't be covered by your warranty. Do not attach a temporary vehicle license, tape or decals across the defogger grid on the rear window. There are five instrument panel outlets, three in the center and one at each end. The outlets located at each end of the instrument panel have a feature that the center air outlets do not. These outlets will have air flowing to them in all modes, including defrost, when the climate control system is on. 3-7