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A/C front vents not blowing any air?

Tiny
DMEN05
  • MEMBER
  • 2011 CHEVROLET TAHOE
  • 5.3L
  • V8
  • 2WD
  • AUTOMATIC
  • 120,000 MILES
The front vents at times were not blowing any air, cold or hot, and seemed to be going towards the defrost vents. The rear vents worked fine. This would occur occasionally, now it seems to completely shut down in the front. No air is coming from the front vents, only the rear vents, at all times. The temperature control in the back is fine as well.
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Saturday, July 8th, 2023 AT 11:12 PM

7 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

If it is an airflow direction issue, that is likely related to what is called a mode door actuator. However, if there is no airflow whatsoever, that sounds like the blower motor isn't working for the front.

Let me know exactly what is happening in the front. Is it a direction issue or is the blower motor no longer working?

Additionally, take a look at this link, it explains how to fix an airflow direction issue when it is on defrost only:

https://www.2carpros.com/articles/air-vents-stay-in-the-defrost-position

Let me know.

Joe

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Sunday, July 9th, 2023 AT 8:41 PM
Tiny
DMEN05
  • MEMBER
  • 4 POSTS
At first, the issue was that the air was coming through the front vents, and intermittently, it would cut off and stop. You could hear the air moving, but nothing was coming through the front vents. The defroster vents were working at this time. We would have to stop at times and turn off and on the car, and sometimes the air would flow again through the front vents. Now the car won't push no air through any vent in the front including the defrost vents. You can't even hear any air being moved, which makes me think the front blower might be the culprit for this issue. The rear vents have always worked fine. I'm thinking the door actuator at first was the issue which caused the air to be redirected, but now it seems the blower might be out as well.
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Sunday, July 9th, 2023 AT 9:50 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

If the blower isn't working, that is where we need to start. Otherwise, we won't know if the airflow direction is working.

Here is what we need to do. First, fuses 39 and 70 in the under-hood fuse box are what send power to the blower motor. These fuses should have power at all times. I need you to check the fuse and confirm there is power available.

Here is a link that you may find helpful:

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

If there is power present, we need to bypass the blower control module and locate the purple wire at the blower motor. With the fan requested on and the key on, see if there is power at that wire. If there is, then we know the blower motor has failed.

Here is a link you may find helpful:

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

Let me know what you find or if you have questions. I attached a portion of the wiring schematic below so that you can see what we are dealing with. I highlighted wires related to the power supply. Also, pic 2 shows the fuses to check inside the fuse box.

Take care,

Joe

See pics below.
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Monday, July 10th, 2023 AT 9:22 PM
Tiny
DMEN05
  • MEMBER
  • 4 POSTS
So both fuses are intact and have power flowing through them. I checked the purple wire and it has power to it as well. This should mean the motor is out and needs to be replaced, correct? Would this have caused the symptom of air flow direction as well? Or is this more likely the mode door actuator?
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Tuesday, July 11th, 2023 AT 11:37 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

If you have power to the motor, check the black wire for continuity to ground. If you have ground and power, the motor is bad. If you don't have ground, the module may have failed.

If the motor is the cause, here is a link you may find helpful:

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

Let me know.

Take care,

Joe
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Wednesday, July 12th, 2023 AT 10:55 PM
Tiny
DMEN05
  • MEMBER
  • 4 POSTS
I have ground and power. I was able to replace the blower motor and since I was there, I replaced the module also, just to have everything uniform. At the moment the ac is working at the front vents. All the fan speeds work and the unit can be changed from the floor to the defrost and back to the front vents. Hopefully this was the issue for the directional flow as well. Thanks for the help.
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Thursday, July 13th, 2023 AT 3:14 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

Thanks for the update. And yes, I believe you fixed both issues.

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

Joe
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Thursday, July 13th, 2023 AT 4:13 PM

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