99 GranAm 4 cyl automatic I have steadly lost different speeds on my blower motor for my car. How can I tell if its the blower motor or speed switch? I only have high speed left.
If the motor is still running on some speeds, it is not the motor. The most likely problem is the blower motor resistor. This unit puts different resistances in the circuit to limit the voltage to the motor. Locate this unit and then disconnect it from its connector. Use a voltmeter to probe from each part of the connector to the ground with the ignition switch on. One should be live and each setting of the blower switch as you try different positions. If this is the case, the resistor is at fault. If you don’t get a voltage reading, the problem is in the switch.
A firm sympton of resistor failure is only having high speed