AC / Heater Blend door issue?

Tiny
PJINHOUSTON
  • MEMBER
  • 1999 CHEVROLET TAHOE
  • 5.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 185,000 MILES
Changed the control module and the actuator and still no heat. Took actuator off and manually moved the blend door and it blew very hot. Checked actuator for movement and it moves but not much. Also, I can't get the actuator opening to match the angle of the blend door mount. Shouldn't one turn to match the other so it can be slid on?
Saturday, November 25th, 2023 AT 10:57 AM

14 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,643 POSTS
Yes, it should. I would reset the HVAC system and the actuator should calibrate itself, also what brand actuator did you get? I have seen many defective actuators which don't work correctly, FYI.

https://www.2carpros.com/articles/step-by-step-guide-to-reset-your-cars-hvac-system-an-essential-for-every

This guide may help as well:

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

Please go over these guides and get back to us.

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Sunday, November 26th, 2023 AT 12:51 PM
Tiny
PJINHOUSTON
  • MEMBER
  • 8 POSTS
I tried 3 different actuators and none of them lined up with the blend door shaft. Also, I could not turn the shaft enough to line up the actuator connect opening area. I tested the actuators before installing and ensured they were all turning which they did. I could change the blend door manually and the heat blew hot. I also reset the HVAC system every time I tried a new actuator. I tried off-brand actuators and an ACDelco.
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Sunday, November 26th, 2023 AT 1:14 PM
Tiny
PJINHOUSTON
  • MEMBER
  • 8 POSTS
I have cash if anyone can fix this and lives in the Houston, TX area.
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Sunday, November 26th, 2023 AT 1:16 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,643 POSTS
Thank you for that but we don't have anyone close to TX. Can I ask how you got the actuator installed if it does not line up? Here are the instructions on how to replace it. Also, did you check the HTR- AC fuse in the fuse panel? Here is a wiring diagram for the actuator so you can test the connection between the actuator and the HVAC controller.

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

Check out the images (below). Let us know how it goes.
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Monday, November 27th, 2023 AT 8:57 AM
Tiny
PJINHOUSTON
  • MEMBER
  • 8 POSTS
At one point it appeared to snap into place but still won't turn the blend door. I am taking to an hourly mechanic tomorrow. My hands are all cut up and I'm tired of dealing with this awful feat of engineering.
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Monday, November 27th, 2023 AT 1:03 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,643 POSTS
Okay, I understand, please let me know what they say. Did you try the HVAC system reset?
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Tuesday, November 28th, 2023 AT 8:50 AM
Tiny
PJINHOUSTON
  • MEMBER
  • 8 POSTS
Yes, several times.
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Tuesday, November 28th, 2023 AT 9:23 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,643 POSTS
If the wiring and actuator are good it must be the HVAC controller, but you said you replaced that, correct?
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Tuesday, November 28th, 2023 AT 9:52 AM
Tiny
PJINHOUSTON
  • MEMBER
  • 8 POSTS
Yes, this new mechanic is telling me I have the correct actuator and I have used 2 new control modules. He is working on it now.
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Tuesday, November 28th, 2023 AT 9:55 AM
Tiny
KEN L
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Okay, let me know what he finds.
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Thursday, November 30th, 2023 AT 9:12 AM
Tiny
PJINHOUSTON
  • MEMBER
  • 8 POSTS
Changed out the blend door actuator under the dash through the cigarette lighter and changed the heater valve and solenoid under the hood and now works fine.
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Thursday, November 30th, 2023 AT 10:36 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,643 POSTS
I am glad you got it fixed, so the blend door actuator has bad again? Here is the heater valve he replaced to fix the problem.
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Friday, December 1st, 2023 AT 9:12 AM
Tiny
PJINHOUSTON
  • MEMBER
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I had the correct actuator. I just didn't know the proper sequence to align the actuator with the blend door shaft so it would properly align and then calibrate.
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Friday, December 1st, 2023 AT 9:29 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,643 POSTS
Thanks for letting us know, we are here to help, please use 2CarPros anytime.
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Saturday, December 2nd, 2023 AT 10:27 AM

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