Have been having problems with the radio power/volume fluctuating day to dayfor the past few months on my 740 wagon, often settling on distortion at low levels. The other week I started the car and had no power going to the radio or windows. After re-starting the car everything worked fine. Then a couple days I go I was sitting in the car listening for a brief period to the radio with the ignition off and found the radio volume to be affected by turning up the fan speed. The fan blower is on its last legs, always on low and sometimes making a screeching sound. Judging from other posts I'm guessing the blower could be the culprit but would like more input. Thanks.

 

I would also check the electrical part of the Ignition switch as well.

 

thanks for the quick response. I think the ignition/key is the source of the problem. I've been using my spare key the last 2 days and the radio's volume is back and the fan no longer runs in the off postion. The older key appears to be much more worn than the spare. Will assume the problem is fixed until symptoms reappear. thanks again.