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I have an '08 Charger that I have been having some issued with the HVAC. At first it would just take 30 seconds for the blower motor to turn on. Now there's absolutely nothing. The only thing that makes me think it's not the blower motor is that the rear defroster will turn on for .5 seconds and then turn off. Why would a dead blower motor do that? I've checked all the fused and swapped relays around and I am at a dead end.

Any help is greatly appreciated.


Much love,


Andrew
 

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The rear window defroster is electric heated wires in the glass & functions separately from the front HVAC blower motor. It could be the blower motor. If you have the manual temp controls it could be the blower motor resistor block. If you have the auto temp controls it could be blower motor power module.
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The rear window defroster is electric heated wires in the glass & functions separately from the front HVAC blower motor. It could be the blower motor. If you have the manual temp controls it could be the blower motor resistor block. If you have the auto temp controls it could be blower motor power module.
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I still feel these issues are related, because they all showed up at the same time. I have not checked into the blower motor resistor block but I do have manual temp controls. Everything I've read about the blower motor resistor being bad leads to you not being able to control speed/temp of the blower. Not the blower motor going completely dead. Will that completely kill power to the blower motor/ HVAC module?

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The blower motor resistor has multiple resistor wires, each of which will reduce the current flow through the blower motor to change the blower motor speed.
The blower motor switch in the MTC heating-A/C system directs the ground path for the blower motor through the correct resistor wire to obtain the selected speed. With the blower motor control in the lowest speed position, the ground path for the blower motor is applied through all of the resistor wires. Each higher speed selected with the blower motor control applies the blower motor ground path through fewer of the resistor wires, increasing the blower motor speed.

I don't know how common it is for the blower motor resistor to fail versus the blower motor.
You can test the blower motor resistor using the following procedure:
1. Disconnect and isolate the negative battery cable (main battery).
2. Disconnect the wire harness connector from the blower motor resistor
3. Check for continuity between each of the blower motor switch input terminals, of the blower motor resistor, and the resistor output terminal. In each case there should be continuity.
If no continuity, replace the blower motor resistor.
If there is continuity, the blower motor resistor is good. You can then check the wire harness circuits for the blower motor switch and the blower motor.

Caution: Do not operate the blower motor with the blower motor resistor removed from the circuit. Failure to take this precaution can result in vehicle damage.
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