How to easily tell if the blower motor in your car is bad. this video will also show you how you can get your cars blower motor going again. If tapping on it does not work and your blower motor is not working on any speed you can just go under the dash below the glove box on most cars and unplug the 2 pin connection going to the blower motor to make sure you have 12volt with a multimeter or a test light and if you do that mean your blower motor is bad.
But in most cases just tapping on it can get it going again a lot of the timing. If it does then you know it will need to be replaced because the brushes in the motor are wearing out.
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