Blend Door Actuator Replacement

md71 · August 19, 2010

Hello

I have a 2006 Silverado with a bad blend door Actuator. It has been trouble shot at the dealership and this was the outcome. I tried the disconnect battery reboot several times with NO luck. The air will only blow thru the defrost which I hear is a default setting for when the door goes bad. I do want to install the new one myself. I just wanted to see if any of you have tried this and what has to be removed.

Thank you

safeman · August 19, 2010

Hi

Before you spend the $$ and time on a new actuator, try this actuator recalibration procedure. I had the same problem and it worked for me. This is a common problem after you disconnect the battery.

With the ignition switch in the on position, remove the HVAC/ECAS fuse for a minimum of 10 seconds. This fuse is located in the under hood fuse/relay box.

Re-install the HVAC/ECAS fuse.

Start the vehicle.

Wait 40 seconds for the HVAC control module to self-calibrate

Try this..... it SHOULD work

md71 · August 19, 2010

i will try this tonight and let you know the outcome.

thank you

safeman · August 19, 2010

Great. I hope it works for you.

Scottorado · January 6, 2011

I had the same problem on my 2001. I removed the actuator and found it was binding up when turned to the full hot postilion. What I found was the actuator servo was not factory calibrated correctly. There is a position potentiometer (pot) geared (blue) off of the output gear. It was off one tooth so that the servo would continue to try and drive the output gear past the stop on the case, causing the gear train to bind up. I carefully moved the blue position pot gear one tooth until the servo ran freely, stopping gently at each stop. It now seems to work fine.

I don't believe the heating system is tied to the computer on my 2001 LS at all. It does not have dual climate control.

WARNING:

Dissembling the servo (actuator) can result in loosing synchronization of the position pot, and if you are not familiar with servos, you may never get it working again.

Also, there is a GM bulletin about actuators that says not to apply power to a loose actuator. (I did a bunch of times with no problem, but consider your self warned, it may vary by year and trim level)

Scott

RAF · January 14, 2011

Good tips. Luckly I don't have this issue with my truck but it seems to be very common so I'm subscribing now for the day I need to go back to this thread to re read the procedure

Thanks

Scottorado · January 15, 2011

Ignore my above post. I still have the hot air sticking on, but only after it has been hot a while. It is more complicated.

Scott

mkimber · January 16, 2011

My 01 had the hot air sticking problem too Scott. A new actuator fixed it. I didn't know about what you described at the time so I just put a new one in. I might try that since my '02 is starting to stick now too.

MonkeyBiz · February 21, 2011

Hi
Before you spend the $$ and time on a new actuator, try this actuator recalibration procedure. I had the same problem and it worked for me. This is a common problem after you disconnect the battery.

With the ignition switch in the on position, remove the HVAC/ECAS fuse for a minimum of 10 seconds. This fuse is located in the under hood fuse/relay box.

Re-install the HVAC/ECAS fuse.

Start the vehicle.

Wait 40 seconds for the HVAC control module to self-calibrate

Try this..... it SHOULD work

Do you know id this will for the a 99? I can't find a HVAC/ECAS fuse in any of the fuse blocks.

txab · February 21, 2011

Hi
Before you spend the $$ and time on a new actuator, try this actuator recalibration procedure. I had the same problem and it worked for me. This is a common problem after you disconnect the battery.

With the ignition switch in the on position, remove the HVAC/ECAS fuse for a minimum of 10 seconds. This fuse is located in the under hood fuse/relay box.

Re-install the HVAC/ECAS fuse.

Start the vehicle.

Wait 40 seconds for the HVAC control module to self-calibrate

Try this..... it SHOULD work

Do you know id this will for the a 99? I can't find a HVAC/ECAS fuse in any of the fuse blocks.

You can also disconnect the battery.

MonkeyBiz · February 22, 2011

Hi
Before you spend the $$ and time on a new actuator, try this actuator recalibration procedure. I had the same problem and it worked for me. This is a common problem after you disconnect the battery.

With the ignition switch in the on position, remove the HVAC/ECAS fuse for a minimum of 10 seconds. This fuse is located in the under hood fuse/relay box.

Re-install the HVAC/ECAS fuse.

Start the vehicle.

Wait 40 seconds for the HVAC control module to self-calibrate

Try this..... it SHOULD work

Do you know id this will for the a 99? I can't find a HVAC/ECAS fuse in any of the fuse blocks.

You can also disconnect the battery.

I thought that is what causes the prolbem in the 1st place?

monstermarlin · April 27, 2011

Hi
Before you spend the $$ and time on a new actuator, try this actuator recalibration procedure. I had the same problem and it worked for me. This is a common problem after you disconnect the battery.

With the ignition switch in the on position, remove the HVAC/ECAS fuse for a minimum of 10 seconds. This fuse is located in the under hood fuse/relay box.

Re-install the HVAC/ECAS fuse.

Start the vehicle.

Wait 40 seconds for the HVAC control module to self-calibrate

Try this..... it SHOULD work

Do you know id this will for the a 99? I can't find a HVAC/ECAS fuse in any of the fuse blocks.

You can also disconnect the battery.

I thought that is what causes the prolbem in the 1st place?

alright, after trying to re-calibrate about a hundred times, i took the top cover off the actuator, flipped the gears so the cooling door would be open as i installed the actuator. it worked. skrew these chevy ac's. i am sick of waisting my bleeping time on nonsense.

crzyh2o · April 28, 2011

I am also having a clicking noise from the passenger side heater actuator door. in recalibrating the actuators at what position would you put the dash controls to do the calibrations? Any help would be greatly appreciated.

thanks in advance,

2003Yukonxl · May 7, 2011

I am also having a clicking noise from the passenger side heater actuator door. in recalibrating the actuators at what position would you put the dash controls to do the calibrations? Any help would be greatly appreciated.

thanks in advance,

I have a 2003 Yukon XL Denali that had similar symptoms to those described in this thread. Air only blowing out the defrost vents and a very loud clicking noise coming from what seemed to be the instrument cluster. After reading dozens of forums, I realized the cause was the blend door actuator. This occurred immediately after starting the vehicle for the first time after replacing a headlight (replacing the drivers-side headlight requires removing the battery).

Somehow the blend door controller can get confused when the battery is removed and then re-installed. In my case, the controller kept the motor in the actuator running even after it hit up against the stop. There are several plastic gears inside the actuator and one of the teeth of the largest gear snapped off. This was the source of the clicking noise. While the cause is not clear, I will be implementing the reset steps after every battery removal to try to avoid this happening again.

A few notes on fixing the issue:

1) What the autoparts store described as the "Primary Actuator" is located directly above the gas pedal in a very tight spot. The kick panel just under the steering wheel is the first thing to remove. Take out the 2 screws on bottom. The top then theoretically pops off but mine took lots of pulling, prying and skin scraps to remove.

2) Next I removed a short vent pipe just above the brake pedal and then removed the electronic control module that was just above the vent pipe.

3) At this point and with some body contortions, I was able to see the actuator. It has 2 mounting screws (6mm). The bottom screw was easy to remove but the top was a bear due to obstructions. I was able to get at it using a flexible nut driver attachment.

4) Before removing the actuator, take a good look (maybe even a few pics) at the actuator arm that is attached to the actuator. Both have to be removed at the same time. The outer edge of the arm has 2 slots: The outer slot connect to a white geared arm that controls a flapper, while the inner slot connects over a black bump (which is essentially a cam that controls another flapper). Take note of how the gears of the actuator arm line up with the white arm.

5) It is a little tricky but you can work the actuator/actuator arm assembly out from under the dash.

6) The arm pulls straight off the actuator. Mine was a bit stuck and took a fair amount of encouragement.

7) I removed the 3 screws holding the cover on the actuator and noticed the broken teeth on the large sprocket. At the time, I did not realize the large sprocket only rotates about 1/4 of a revolution when in use. I could have tapped the sprocked off the metal spline, and then rotated the sprocket on the spline such that the broken teeth would be positioned outside the range of use. Not having yet realized this, I went to the parts store and bought a replacement for $140. Given this part fails regularly, they had them in stock.

8) Re-installing the actuator/actuator arm assembly was very challenging, particularly since I did not take the mental notes/pics as recommended above. Aligning the teeth on the 2 arms turned out to not be necessary. When the controller self-calibrates, the teeth line themselves up. The most important trick is to the both cams (one on the back side of the white toothed arm, and the other on the vent flapper assembly) in the slots of the actuator arm.

9) Be sure to do the calibration step (after connecting all wiring harnesses back, pull the 10A HVAC fuse in the box under the hood as described in this forum).

Much thanks to all those you have contributed to this forum. Replacing this part would have been much more challenging without all the posts.