Q: Drivers side rear view mirror defogger not working and how do I repair?

Hello, thank you for writing in. The defroster within the mirror is rather simple. It uses a resistor to collect electrons which ends up resulting in heat. it is this heat that is used to defrost/defog the mirror. If the defroster is not working, you will want to look into the electrical power supply. If the unit is receiving power, and not heating up, it is likely the heater itself needs to be replaced. If the unit is not receiving power, you will need to look into the switch and the wiring. The switch may not be letting power through to the unit, and this can be tested by checking for voltage after the switch. The wiring may not also be carrying the current to the resistor. Both of these components can be tested. For more help with diagnosing the issue, contact our service department.