Air conditioner front vents do not blow heat or anything?

Tiny
DRANMA
  • MEMBER
  • 2004 CHEVROLET TRAILBLAZER
  • V8
  • 4WD
  • AUTOMATIC
  • 200,000 MILES
The A/C doesn't work, the front vents don't blow heat or anything, and the rear vents on the ceiling only start blowing some heat or air sometimes for a about 5 minutes and then stops I've checked the fuses and they are good I don't know what it is for sure unless it's the actuator.
Thursday, March 28th, 2024 AT 3:32 PM

3 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
Hi,

Does the blower motor work at any speed? Can you hear it run? Can you get air flow from under the dash or defroster?

Let me know because there are different actuators. For example, the air temperature entering the vehicle is controlled by a blend air door actuator. The airflow direction is controlled by a mode door actuator. There are others as well.

Let me know.

Take care,

Joe
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Thursday, March 28th, 2024 AT 8:33 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,513 POSTS
This sounds like a mode actuator which controls the vent operation, here is the location so you can check it out.

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.

1. Place the ignition switch to the Off position.
2. Disconnect the scan tool.
3. Install the HVAC control module.
4. Connect all previously disconnected components.
5. Start the vehicle.
6. Wait 40 seconds for the HVAC control module to self-calibrate.
7. 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.

Check out the images (below). Please let us know what happens.
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Friday, March 29th, 2024 AT 9:11 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,513 POSTS
Anything?
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Saturday, May 11th, 2024 AT 12:59 PM

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