A rear-window defroster and a car radio seem like two separate systems until the signal starts to get noisy the moment the defroster is switched on. Drivers usually notice static, weaker reception, or a station that fades in and out once the rear glass starts heating. Then the signal improves again after the defroster is turned off. That is not a coincidence. Yes, The Rear Defroster Can Affect Radio Reception On many vehicles, the rear defroster grid and the radio antenna are both built into the rear glass area. Even when they are separate circuits, they are close enough together that an electrical problem in one can affect the other. The defroster pulls a strong electrical load, and once there is poor grounding, damage in the glass grid, or extra resistance in the circuit, interference starts showing up through the radio. This is why the issue usually appears only when the defroster is on. The radio may sound fine the rest of the time, then suddenly fill with stat ... read more