First let me say that I know nothing specifically about your car or this problem. However, from the point of view of electronics I can address your statement about solid state electronics. Electronics can indeed make noise. Especially switching regulator circuits. I do not know what type of regulator is in there but I have seen cases where a capacitor goes bad and will make noise. I am not talking about blower regulators but just regulators in general. Anyway it sounds like you have figured it out yourself: Get a new regulator.

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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra