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The blower fan is not working why?

Tiny
TOPCAT3HI
  • MEMBER
  • 2005 CHEVROLET SILVERADO
  • 4.8L
  • V8
  • 2WD
  • AUTOMATIC
  • 115,062 MILES
Blower fan works intermitantly, the finally quit completely.
Tuesday, June 30th, 2020 AT 10:42 AM

30 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good afternoon.

I attached a wiring diagram for you to view.

We need to do some testing for the blower motor control circuit.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Do you have a volt meter or test light to do some testing? This could be the blower motor itself or the resistor.

https://www.2carpros.com/articles/how-to-check-wiring

Roy

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Wednesday, April 28th, 2021 AT 12:49 PM
Tiny
BILLY J RIGGS
  • MEMBER
  • 2 POSTS
  • 2004 CHEVROLET SILVERADO
  • V8
  • 2WD
  • AUTOMATIC
  • 54,654 MILES
What typically causes the blower to suddenly stop working?
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Friday, April 30th, 2021 AT 2:23 PM (Merged)
Tiny
OBXAUTOMEDIC
  • MECHANIC
  • 3,711 POSTS
A fuse or relay.

Sometimes the Blower Motor Resistor, usually you will have one or two of the fan speeds only seen one that were just quit all together.
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Friday, April 30th, 2021 AT 2:23 PM (Merged)
Tiny
BILLY J RIGGS
  • MEMBER
  • 2 POSTS
Thanks for the insight. I changed the Blower Motor Resistor and pigtail (available from the Chevrolet dealer) and solved the problem in about fifteen minutes! For the record, the high speed (5) had stopped working several months ago. We are in the 100's these days so the A/C is constantly in use.
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Friday, April 30th, 2021 AT 2:23 PM (Merged)
Tiny
OBXAUTOMEDIC
  • MECHANIC
  • 3,711 POSTS
No problem. Keep Cool. HaHa
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Friday, April 30th, 2021 AT 2:23 PM (Merged)
Tiny
BFELDHAHN
  • MEMBER
  • 1 POST
  • 2004 CHEVROLET SILVERADO
  • 6.6L
  • V8
  • 2WD
  • AUTOMATIC
  • 125,000 MILES
The AC and blower motor will be working fine and then it just stops (on all speeds), and the AC and re-circulation lights stay lit. If I turn the engine off/on it seemed to fix it for a while but it is becoming a more frequent issue and restarting the engine has no effect. If I mess with it i.E turn it off for a period of time or just keep cycling the AC/re-circulation buttons it may come on. I'm not really sure that performing these actions really had anything to do with temporary resolution of my issue but all I can find on the Internet is the resistor issue. I took advantage of the resistor recall and had Chevrolet replace the resistor but that has been at least 5 years ago. Any help would be appreciated.
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Friday, April 30th, 2021 AT 2:23 PM (Merged)
Tiny
SCGRANTURISMO
  • MECHANIC
  • 4,897 POSTS
Hello,

This could be a problem with Ground #200, which is located on the right side of the dashboard. In the diagrams down below I have included the Ground Distribution Wiring Diagram for your vehicle's Blower Motor, as well as a diagram of the location of Ground #200, and a guide for how to inspect the ground. Please go through these guides and get back to us with what you are able to find out.

Thanks,
Alex
2CarPros
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Friday, April 30th, 2021 AT 2:23 PM (Merged)
Tiny
ALGAJR
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  • 5 POSTS
  • 2004 CHEVROLET SILVERADO
  • 133,000 MILES
My blower motor is not working. I changed the resister, and the connecting harness that connects to it. I also checked the fuse and the fuse is good also, there is power coming from the connector going into the resister, but the pigtail that comes from the resister and plugs into the blower motor does not have power coming from it.
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Friday, April 30th, 2021 AT 2:23 PM (Merged)
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
There are three fuses (HVAC, heater and blower) that run the system so make sure you check all of them. Here is a wiring diagrams and a guide to help you test the fuses with their locations:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

If everything checks out we need to test the blower motor this guide with show you how.

https://www.2carpros.com/articles/blower-fan-motor-works-on-high-speed-only

If the motor checks out I would check the connection and wiring between the controller.

https://www.2carpros.com/articles/how-to-check-wiring

If all is good the controller is bad and needs to be replaced.

Check out the diagrams (below). Please let us know what you find.

Cheers
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Friday, April 30th, 2021 AT 2:23 PM (Merged)
Tiny
ALGAJR
  • MEMBER
  • 5 POSTS
There is no other power going into the resister besides the power from the red wire, I test all the wires and turned the knob on the control switch to all the speeds.
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Friday, April 30th, 2021 AT 2:23 PM (Merged)
Tiny
ALGAJR
  • MEMBER
  • 5 POSTS
I checked the fuses and their not blown, I rechecked the wires and cycled through the switch and the only one with power is the red wire. Can the problem be the AC control switch?
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Friday, April 30th, 2021 AT 2:23 PM (Merged)
Tiny
ALGAJR
  • MEMBER
  • 5 POSTS
I checked the fuses and they are not blown. I rechecked the wires and cycled through the switch and the only one with power is the red wire. Can the problem be the AC control switch?
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Friday, April 30th, 2021 AT 2:23 PM (Merged)
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
If you are sure about the results of those tests, then you have a bad switch which means you need a controller. Here is a guide to help.

Check out the diagrams (below). Please let us know what happens.
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Friday, April 30th, 2021 AT 2:23 PM (Merged)
Tiny
ALGAJR
  • MEMBER
  • 5 POSTS
The controller did it all fixed! Thanks for hanging in there with me. :) I love this site.
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Friday, April 30th, 2021 AT 2:23 PM (Merged)
Tiny
TELLME6532
  • MEMBER
  • 1 POST
  • 2004 CHEVROLET SILVERADO
  • 5.3L
  • V8
  • 4WD
  • AUTOMATIC
  • 178,000 MILES
I have replaced the 7 wire plug at the resistor that goes to the motor, also replace resistor. I have used a 12 v tester on all 5 speeds all have light on the 7 plug end on the proper abcdefg line markings in proper order. Even have a light at the plug end of resistor that plugs into motor on all 5 speeds, but when plug into blower motor nothing have tried a new blower motor but still no fan movement.I ran two wires to the blower motor straight from 12v source fan very powerful that way. Any ideas?
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Friday, April 30th, 2021 AT 2:23 PM (Merged)
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
We need to back track to find out what the voltage is at the control processor (resistor). I understand you have voltage but we need to know how much voltage on each wire. Let's start with A. This should be 12 volts at all times. Next B, this should be different depending on what speed you have the fan set on. So let's check it on each setting.

Clearly if the blower motor comes on when you put 12 volts to then I suspect we have a wiring issue where you are not getting 12 volts on the B+ wire. If you don't have 12 volts there then the blower will not operate.

Let us know what the actual voltage is on each of these wires by back probing the connector with it turned on.
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Friday, April 30th, 2021 AT 2:23 PM (Merged)
Tiny
MAHOCKEY
  • MEMBER
  • 1 POST
  • 2003 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 15,000 MILES
The blower works on #5 1 thru 4 blower does not work?
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Friday, April 30th, 2021 AT 2:23 PM (Merged)
Tiny
SERVICE WRITER
  • MECHANIC
  • 9,123 POSTS
Sounds like a resistor or relay problem, outside chance of switch or wiring. The high speed runs a different course to the motor.

this guide will help

https://www.2carpros.com/articles/blower-fan-motor-works-on-high-speed-only

Please run down this guide and report back.
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Friday, April 30th, 2021 AT 2:23 PM (Merged)
Tiny
2CP-ARCHIVES
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  • 2003 CHEVROLET SILVERADO
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What would cause blower not to work on heater/ac
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Friday, April 30th, 2021 AT 2:23 PM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
At the blower motor, the purple wire is voltage, black wire is ground. Note the diagram. The red wire to processor is fuse protected, blower fuse. There are a couple other fuses, that go to the hvac control module.
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Friday, April 30th, 2021 AT 2:23 PM (Merged)

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