79 Spider 2000 radio static

[barnesjtsl]

Just started happening about a week ago. When I turn on the heater fan I get a little static over the radio? It is not real bad and I can live with it but don't want to.

Condenser on the coil?

Thoughts,

barnestjsl

[TX82FIAT]

Assume the static is only when the heater fan is on and not when other components are turned on like headlights. Does the static change with RPM's? Is it a whine sound that fluctuates with the car RPM or a faint constant static? If faint non RPM changing static check your antena as well as the grounds reviewing the fan ground location and the radio ground location. if the static changes with the RPM's it is most likely a grounding loop issue that is activated by the heater fan circuit. The ground will look for the path of least resistance and the ground may be altered when the fan is turned because of a flaw in the circuit. Also, the gauge wire of the ground needs to be equal or even greater gauge than the 12 volt source in for the radio. Electric current is fickle and does not always go where we want.

it could be as simple and a speaker wire is hitting the chasis at some point creating another ground and an inbalance in the system. Only doing it when the fan is on could be related to the amount of current across a common circuit moving to ground than the fan itself. Hope this helps. It took me four months to track down a grounding loop on my stereo unit that had to do with the ground for my amp in the trunk and the ground from the head unit in the front of the car. I had to run a much thicker gauge ground wire from the head to the common ground in the trunk to correct the inbalance as well as compensate for the additional resistance along such a long grounding path. Hope this helps in some way?

[mpollock]

If you have been under the dash make sure no wiring was moved around and now picking up noise. If nothing else has changed it could be that the brushes on the fan motor are going bad. You might be able to knock out the noise by putting a capacitor across the DC input to the fan motor and/or the radio. You should get something suitable at Radio Shack.

[bobplyler]

It could be that the brushes in the motor have gone bad, and are generating small sparks. About 30 years ago, when I was working in Atlanta, I got a call when I got to work. "Your code broke last night." It turns out that one of the motors had bad brushes, and was resetting a latch.