my bmw radio zones out as soon as defroster is turned on?

Is the radio antenna placed in the rear window (there should be two vertical wires placed perpendicular on the defroster). If that is the case and your radio zones out it means that the antenna is no longer isolated from the defroster circuit causing current to pass the antenna. Check the defroster and antenna circuit on the rear window for intreruptions. You may have to change the rear window which will mean a lot of money.

Is the radio antenna placed in the rear window (there should be two vertical wires placed perpendicular on the defroster). If that is the case and your radio zones out it means that the antenna is no longer isolated from the defroster circuit causing current to pass the antenna. Check the defroster and antenna circuit on the rear window for intreruptions. You may have to change the rear window which will mean a lot of money.