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The blower motor stopped working; it has no power?

Tiny
DBREWER99
  • MEMBER
  • 2012 CHEVROLET SONIC
  • 1.8L
  • 4 CYL
  • 2WD
  • MANUAL
  • 186,000 MILES
The blower motor spontaneously stopped working. I grabbed lunch at work, and it was working. When I left for the day, it was no longer functioning. I have replaced the blower motor, the resistor and all three of the related fuses. I have also replaced the control panel. I have tested voltage and there is no voltage to the motor. There is also no power to the 10-amp fuse in the dash (position 32 I think). The 40-amp j case fuse and other 10-amp fuse have voltage to them. I am not very good at electrical and am hoping you can shed some light. Thanks.
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Friday, July 28th, 2023 AT 5:25 PM

8 Replies

Tiny
DBREWER99
  • MEMBER
  • 6 POSTS
Also note, I have run power directly from the battery and the blower kicks on. I am thinking it is a bad wire from the panel to the fuse, but I am not confident in that. Maybe the violet/brown wire to the fuse.
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Friday, July 28th, 2023 AT 5:44 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,708 POSTS
Hi,

There is a blower motor relay located in the instrument panel fuse box on the left. Have you checked it? I believe fuse 32 (you mentioned above) will only have power when that relay is complete.

Let me know if you checked the relay. Also, the relay primary side receives power from the body control module when the fan is requested. That is what allows the relay secondary to close and send power to the motor.

If you haven't checked the relay, switch it with a different one in the box having the same part number to see if it works. If there isn't one, here is a link that explains how to test the relay and circuit. I suspect this is where the problem is coming from.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Let me know. Also, take a look at the schematic below and let me know what all you have checked.

Take care.,

Joe

See pic below. Note: I had to cut the schematic in half.
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Friday, July 28th, 2023 AT 9:56 PM
Tiny
DBREWER99
  • MEMBER
  • 6 POSTS
I have looked in the panel and cannot seem to find a relay at all. Could it possibly be built into the BCM? The only thing I have been able to locate is the 3 fuses I mentioned. The 40 amp in the engine compartment and two 10-amp fuses in the dash fuse box. There is not an obvious relay in the compartment, only micro fuses.
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Tuesday, November 21st, 2023 AT 2:01 PM
Tiny
DBREWER99
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  • 6 POSTS
Also, would the Violet/Brown wire not be the supply of power to the fuse that is dead? The power should flow from the VIO/BRN wire that supplies the fuse to the Red/BLU wire that supplies the power to the blower itself. I know the VIO/BRN wire comes from the HVAC control panel. Does it route somewhere prior to going to the fuse?
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Tuesday, November 21st, 2023 AT 2:11 PM
Tiny
DBREWER99
  • MEMBER
  • 6 POSTS
Or better yet. Could it possibly be a relay that is labeled as something else? The only relays I see in the instrument panel fuse box are, RUN, RAP/ACCY, Liftgate Release, and then more JCase fuses.
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Tuesday, November 21st, 2023 AT 2:25 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,708 POSTS
Hi,

Fuse 7 (blower fuse 40-amp) in the under-hood fuse box is what actually sends power to the relay and then to the motor. That is the power supply for the relay's secondary side. The wire color is red with a yellow tracer.

Power to the primary side, which is what triggers the relay to send power to the blower motor, comes from the body control (BCM).

Also, and most importantly, you nailed it. The blower motor relay is actually referred to as the "Run Relay". See pics below. I found it in a different manual.

Check that and let me know what you find.

Joe

See pics below.
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Tuesday, November 21st, 2023 AT 8:49 PM
Tiny
DBREWER99
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It was the relay! Thank you for your help!
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Monday, November 27th, 2023 AT 10:40 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,708 POSTS
Hi,

Thanks for the update. I'm glad to know you got that taken care of. It's getting cold. LOL

Take care of yourself and feel free to come back anytime in the future.

Joe
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Monday, November 27th, 2023 AT 8:22 PM

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