Heater blower motor chirps/squeals with feedback into am radio. After first working on old blower motor and reinstalling and then installing a new blower motor and a used blower regulator, blower motor[s] still squeals or chirps on low and auto (when auto is near low, when on blower on high or auto is high there is no whine). Almost always occurs when auto starts until auto is at high. For sure it is not the blower motor bearings. I have one old motor and one new one, they both do the same. Noise sounds like it is coming from windings. It makes no difference whether the blower motor[s] is installed in blower motor housing or if it is sitting on the floor of car all hooked up and running outside of the housing, the blower motor still makes this whining, squealing, chirping or whatever we want to call it on low or low/auto. When the blower motor picks up speed, noise also does until it gets near high. For sure there is no noise at high and it blows like crazy. This noise feedbacks into radio when AM is on. New radio by the way. Got the problem solved for about a week by cleaning up the regulators connections. Then it came back. Have talked to many in the know. Most have never heard such a thing. A few say it is the regulator. Any ideas, before I keep replacing parts?

I will betcha that any appliance repairman can find the problem. Should be easy with the blower making a racket when bench tested.

I, too, have heard rumors to the effect that the regulator can cause this issue.

But, personally, I've not had the problem yet.

If you replace the regulator, PLEASE post again and let us know the result.

It does seem as though you've covered all other bases regarding the motor itself. On the high setting, the regulator is not in the circuit......the full battery voltage is sent to the motor. This may be another piece of data to ponder.

One cheap way of testing the motor at lower speeds is to get a resistor and put it in series with the motor. If the problem does not exist with the resistor, you'll have further confirmation that the regulator is the culprit.