HVAC blower not working

2003 CHEVROLET 1500
190,000 MILES • 5.7L • V8 • 4WD • AUTOMATIC
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ELI012456
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Blower not working at any setting.Replaced with new one.Still not working.Wires to blower have 8 volts even with ignition off.Also ac compressor will only kick in if I use the defrost button but not with the ac button.Can this be the the controls.
Dec 10, 2019 at 3:44 PM
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KASEKENNY
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Do you have an auto system or manual controls? Based on your statement I am assuming you have an auto system. If this is the case, it could be the module.

However, this could also be the blower motor processor. If you look at the wiring diagram the HVAC module tells the processor what to do by adding a load to the ground side of the blower motor. By doing this is decreases the voltage that the blower motor uses which slows down the motor.

Can you tell me where you measured this voltage? Looking at the diagram you should have voltage there because the blower is hot at all times. This is a ground side control so the motor will not turn on until the module grounds the circuit.
Dec 11, 2019 at 3:51 PM
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ELI012456
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I tested voltage on purple wire going to motor. The voltage was 8 volts. I stated voltage even with ignition off but it did slowly decrease over a short time.
Dec 11, 2019 at 4:38 PM
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ELI012456
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It is an auto system.
Dec 11, 2019 at 4:39 PM
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KASEKENNY
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Okay. Just check to make sure the ground is good by checking continuity to ground. I suspect it is fine but we need to make sure. If this is okay, then I suspect the control module is your issue.
Dec 11, 2019 at 4:57 PM
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ELI012456
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Okay.I will check the ground.can't get to it until the weekend.I will let you know what I find. I have been thinking it is the controls.
Dec 12, 2019 at 11:45 AM
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ELI012456
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You were a big help.Got it working.You have me enough info to track down now to test the climate control module.And after testing that out as ok the only thing left was the blower control module. Replaced that and all works fine. Thank you for your help.
Dec 22, 2019 at 6:59 PM
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KASEKENNY
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Awesome. Thanks for the update. I am sure that info will help others that have this issue. Glad I was of some assistance. It is very typical that we can get you close but you are the ones that fix these things. Good work. Hope you come back to 2CarPros next time you need assistance. Thanks
Dec 23, 2019 at 7:27 PM