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Heat and ac suddenly quit working on my 2003 gmc sierra. I've never had any problems with it. I am getting no air flow. How do I tell if I need to replace the resister or the blower motor

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The fan is easier to test, it's only 2 wires. Power and ground, easy test. Check the pigtail ( connector ) for corrosion.. To test resistor you'll need a voltmeter to test wires at fan. Fan only knows on and off. The resistor changes ground for other speeds. You could just try tapping on motor to see if it spins if it does change it

Posted on Nov 21, 2013


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