The heater fan on my 98 chevy silverado stopped working... worked on high at first but made a high pitched noise and stopped all together

Run 12V directly to the motor and see if it will run, if it dosent than the motor is bad, if it does than the resister is bad, the resister makes the blower run and also regulates the speeds for the blower, but chanses are if it was making a high pitch squeel before it quit the motor went out.