Front Vents Not Working

Tiny
DBOOGIE
  • 2004 CHEVROLET TRAILBLAZER
  • 71,000 MILES

Recently my front vents stopped working on my 2004 Chevy Trailblazer. I've tried to recalibrate by taking out the fuse, waiting a couple minutes, putting the fuse back in, turning the car to run, letting it go through its motions, but that didn't work. The air blows cold, but it is only coming out at the feet, side vents and defrost. Do you know what could be the cause?

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Thursday, May 3rd, 2012 AT 5:08 PM

14 Replies

Tiny
PROMECHANIC
  • EXPERT
  • 550 POSTS

It sounds like you have a blend door actuator that has gone out. Here is a guide that will show you which actuator to replace.

https://www.2carpros.com/articles/replace-blend-door-motor

Here is what it will be like on your car.

Please let us know what happens.

Cheers,

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Thursday, May 3rd, 2012 AT 7:05 PM
Tiny
DBOOGIE
  • MEMBER

Ok, thanks for your help! I will try that!

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Thursday, May 3rd, 2012 AT 8:28 PM
Tiny
PAULCOBBLE
  • MEMBER

We have a 2005 trailblazer that has been having the same problem. We took it back 2 different times within the first year for the same thing. Amazingly when we took it this time they was able to tell me what the problem was. When they took it to the shop to check it the A/C was working correctly. When they called us to tell us what was wrong with it, they said that when it has a problem like that it saves the code. He said that the actuator needed to be replaced $250. When we got back to pick it up I asked why they couldn't get the code like that when we brought it in for that 6 yrs ago. He couldn't give me an answer.

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Friday, August 17th, 2012 AT 3:56 AM
Tiny
BIBLIA23
  • 2004 CHEVROLET TRAILBLAZER
  • 4WD
  • AUTOMATIC

My air conditioner only blows the air through defrost or bottom vents, but none through the front, what could it be?

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Wednesday, August 23rd, 2017 AT 4:31 PM (Merged)
Tiny
FIXITMR
  • MEMBER

When you select center what happens?

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Wednesday, August 23rd, 2017 AT 4:31 PM (Merged)
Tiny
DRCRANKNWRENCH
  • EXPERT
  • 3,443 POSTS

Is this a manual or automatic climate system? Does defrost and floor always blow together, at the same time, or does the system transition from floor to defrost when selected. Without a scan tool, it could be kind of a shot in the dark, you could have a faulty actuator, or climate panel/module. You can try a recalibration on the system, but first disconnect the battery cables and short them together for 10 seconds or so to deplete voltage. The procedure is as follows:

Actuator Recalibration (Primary)
When replacing the HVAC control module it will be necessary to allow the HVAC control module to perform a calibration process. When installing the HVAC control module be sure to perform the following:

Important: Do not adjust any controls on the HVAC control module while the HVAC control module is self-calibrating. If interrupted, improper HVAC performance will result.

Place the ignition switch to the OFF position.
Disconnect the scan tool.
Install the HVAC control module.
Connect all previously disconnected components.
Start the vehicle.
Wait 40 seconds for the HVAC control module to self-calibrate.
Verify that no DTCs have set as current DTCs.
When replacing the HVAC actuator it will be necessary to allow the HVAC control module to perform a calibration process. When installing the HVAC actuator be sure to perform one of the following:

Important: Do not adjust any controls on the HVAC control module while the HVAC control module is self-calibrating. If interrupted, improper HVAC performance will result.

Alternate Method (w/o Scan Tool)
Clear all DTCs.
Place the ignition switch to the OFF position.
Install the HVAC actuator.
Connect all previously disconnected components.
Remove the HVAC B fuse for a minimum of 10 seconds.
Install the HVAC B fuse.
Start the vehicle.
Wait 40 seconds for the HVAC control module to self-calibrate.
Verify that no DTCs have set as current DTCs.

Let me know if you need any further assistance with this matter.

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Wednesday, August 23rd, 2017 AT 4:31 PM (Merged)
Tiny
WRENCHTECH
  • EXPERT
  • 20,829 POSTS

The mode doors are controlled by an electric actuator mounted on the driver's side of the HVAC unit under the dash. The actuator may be bad or the linkage may just be stuck.

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Wednesday, August 23rd, 2017 AT 4:31 PM (Merged)
Tiny
NORSKI441
  • 2006 CHEVROLET TRAILBLAZER

WHY WOULD AIR NOT BLOW THROUGH THE VENTS IN THE DASH, BUT WILL BLOW THROUGH THE DEFROST AND FLOOR VENT?

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Wednesday, August 23rd, 2017 AT 4:31 PM (Merged)
Tiny
HMAC300
  • EXPERT
  • 49,799 POSTS

Because one or both of the actuators on the hvac unit aren't working right. They could be stuck or not working at all. Trailblazers were also notorious for the control head going bad. I'll send a generic pic of a hvac so you can see where the actuator is.

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Wednesday, August 23rd, 2017 AT 4:31 PM (Merged)
Tiny
SIMONEMI
  • 1994 CHEVROLET TRAILBLAZER

Regardless of the control setting for AC (max, normal, bi-level) cold air blows from the floor discharges and the vents. The temperature seems cold enough. I also notice that when the vent only setting is used, air also blows from the floor discharge and vents. Please give me your thoughts.

Thanks for the help.

Mike Simone
1994 S10 Blazer, 4.3W engine, 177,000 miles

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Wednesday, August 23rd, 2017 AT 4:31 PM (Merged)
Tiny
BUELLXB9RFB
  • MEMBER

Sounds like a vacum line on your blend door acctuater is bad or off check it out

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Wednesday, August 23rd, 2017 AT 4:31 PM (Merged)
Tiny
ELIZABETH CIANO
  • 2003 CHEVROLET TRAILBLAZER

Air Conditioning problem
2003 Chevy Trailblazer 6 cyl Two Wheel Drive Automatic 176000 miles

where is the fan speed resistor located?

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Wednesday, August 23rd, 2017 AT 4:31 PM (Merged)
Tiny
DOCFIXIT
  • EXPERT
  • 18,993 POSTS

Behoind glove box in air plenum just left of blower motor

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Wednesday, August 23rd, 2017 AT 4:31 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
  • 68,225 POSTS

It sounds like you may have a vacuum leak. If I recall, on the 06 the vent doors are actuated by vacuum. Check to see if there are any leaks.

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Wednesday, August 23rd, 2017 AT 4:32 PM (Merged)

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