the buttons for the heater a/c controls do not work, do not light up. I have replaced the heater controls, nothing changed. replaced the whole radio with face plate, still no changes. checked all fuses. the radio works fine, and when you check the heat dial numbers, it runs from 0 through 16 one number at a time and the blower does work. does anyone know what else to look at, getting cold out and need heat and defrost. also, the display does not show any heat a/c on the right side of the display.