Blend door actuator or controller issue?

twbauer · Aug 22, 2010

OK guys... looking for a bit of help here. I have a 05 Yukon XL Denali. As many other people, I am also having climate control / air conditioning problems. I can only get the air to blow through the defrost vents by the windshield no matter what vent setting the climate control panel is set to. This problem was first encountered about a year ago when I changed the battery in the vehicle. We actually got things working again by removing the climate control panel (below the radio) and unplugged and replugged the 2 harnesses. Bingo.. things started working again.

I recently put in an aftermarket double din Kenwood Nav system. In working through the install, I removed the negative battery lead multiple times, and sure enough the problem showed up again. (Blowing air through defrost vents only) I was able to fix it one time with the procedure I indicated above (unplug and replug the climate control harnesses), but I no longer can get that to work. I tried pulling the HVAC fuses as other posts have indicated, wait 10 seconds, and then turn the vehicle to ACC for about a minute. That didn't seem to work.

I read a bunch of posts about the actuator motors being bad, so I picked one up at an auto parts store. I didn't know which actuator was the issue. I started with the one under the passenger side dash (under the hush cover). This apparently was the wrong one

. I then found the other actuator (the correct one) under the drivers side dash up to the right of the gas pedal. I removed that actuator, and was able to manually turn the vent arm to change the vents that the air blows out. So.. for the time being, until I figure this out, the wife and 4 kids won't bake in the vehicle.

I noticed that even with the actuator removed from the vent assembly, when I changed the position of the climate control to defrost vents, top vents, lower vents, etc... the actuator did NOT move. I then tried plugging in the NEW actuator that I got from the auto parts store. Just like the existing actuators in BOTH locations, when the vehicle had power going to the HVAC system the actuator was moved from just below the lowest setting to the lowest setting, and then back BELOW the lowest setting. It seems to me that it's somehow not getting initialized correctly as both actuators "resting position" is slightly below the lowest position no matter what vent position setting the climate control is set to. I hope that makes sense.

I think I have convinced myself the actuators are not bad. Anyone agree, or think I'm crazy? So, I'm wondering if the consensus here is that the climate control panel is bad? Any way to verify this??? Is there another procedure for initializing the system? Thanks in advance for the assistance!!!
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WHITEOUT · Aug 22, 2010

I noticed that even with the actuator removed from the vent assembly, when I changed the position of the climate control to defrost vents, top vents, lower vents, etc... the actuator did NOT move. I then tried plugging in the NEW actuator that I got from the auto parts store. Just like the existing actuators in BOTH locations, when the vehicle had power going to the HVAC system the actuator was moved from just below the lowest setting to the lowest setting, and then back BELOW the lowest setting. It seems to me that it's somehow not getting initialized correctly as both actuators "resting position" is slightly below the lowest position no matter what vent position setting the climate control is set to. I hope that makes sense.

No clue what you really mean. Kinda sounds like your saying, the temp control, and the blend door actuators are opening to different postions. correct? So if your at high, it is really at medium? I know I did my passenger blend door a few months back, and you need to make sure the temp control knobs and blend door are positioned the same when installed. Google blend door, and you can find a procedure for this. Don't know if I can help, kinda confused on the problem, hopefully somebody else will know

twbauer · Aug 23, 2010

Sorry for the confusion on this... it's not really an easy write up. Let me try again.

On the actuator, there are 3 marks. Long one in the middle and a smaller one on each side. Let's call the first small one "low", middle long mark would be the "mid position" and the other short one would be considered "high". It seems that both installed actuators are outside of the first small (low) mark. When the system first gets power, or when I plug in the new actuator to the actuator harness without being installed, the actuator moves from just left of the low mark, to the low mark, and back to the left again. (nowhere near the mid or high mark)

Yet after the vehicle is started, by pushing the vent buttons on the control panel to change the venting position, there is no change in any of the actuators... even the new one I purchased which wasn't hooked up to the control arms (not installed, but just plugged in).

Hopefully this makes things a bit clearer... Really appreciate your patience here. I gotta find a way to get this working again for my family.

This makes me think that I'm not getting the system initialized properly to detect the full travel of the actuators.

---------- Post added at 12:10 AM ---------- Previous post was Yesterday at 11:48 PM ----------

Another thing I just found... from the online Chilton docs...

Removal & Installation

1. Remove the instrument cluster trim plate bezel.
2. Remove the instrument panel storage tray.
3. Remove the accessory switch assembly from the instrument panel.
4. Remove the screws from the HVAC control assembly.
5. Remove the HVAC control assembly, with the following procedure:
* Release the retaining tabs.
* Pull the control head out of the instrument panel carrier.
6. Unplug the electrical connectors from the HVAC control assembly.

To install:

WARNING- Make sure the ignition key is in the OFF position when connecting the electrical connectors to ensure the proper calibration of the control panel.

1. Engage the electrical connectors to the HVAC control assembly.
2. Install the HVAC control assembly.
3. Install the accessory switch assembly to the instrument panel.
4. Install the screws from the HVAC control assembly.
5. Install the instrument panel storage tray.
6. Install the instrument cluster trim plate bezel.

WARNING- Do not adjust any controls on the HVAC control module while the HVAC control module is calibrating. If interrupted improper HVAC performance will result.
7. Start the vehicle and let run for one minute .

Maybe I'm not doing the reset procedure correctly. What are they talking about in #2 and #3? I'm not sure what the accessory switch assembly is. I'm only pulling the 2 plugs in the back of the climate control panel when I try to reset the unit. Anyone have any ideas? Whiteout??? You seem to be the guru on fixing these... Looking forward to your reply!

WHITEOUT · Aug 23, 2010

Ya bro, I went almost a year with my blend door actuator not working, till I finally figured it out!!! As far as #2 #3 go, it sounds like they are talking about your temp control panel, if you are removing that. Not sure that has anything to do with blend door tho. Kinda sounds just like temp control, ie. HVAC. Usually anything to do with A/C or heating is called HVAC. so maybe they are talking about blend door, but doesn't sound like it.

Are you sure you got the right blend door? Check the numbers on back for clarification. Sounds dumb, but you never know. You diffenently need to let it relearn itself, I made sure to do that also. Wish I could find the website were I got great detailed information about how I did mine. But regretfully can not find, sorry.

ilmk123 · Aug 23, 2010

Hey shoot me a e-mail.........I think I can help you...... [email protected] .........Scott

WHITEOUT · Aug 24, 2010

Forgot I wrote a thread, it's in the tech section, about blend door. It will tell you the exact re-learn process for these blend doors. hope it helps, or hope ilmk123 can help you out. good luck bro

twbauer · Aug 25, 2010

FIXED!!!!!!! I can't believe it!!!

I cleaned the inside of the actuator as someone mentioned in some post I read. Ya know.. it really does make sense. If I know the motor runs when the system is calibrating, it's got to be something wrong with the "electronic sensing" of where the actuator is. It's easy to see that the goop/lubricating compound in there wouldn't allow an electrical connection on the rails, and should be cleaned up. I just used some paper towel on the end of a flat head screwdriver, and also just my finger. I also thought it may be conductive grease. I've seen that in some applications, but that wouldn't make sense either. With multiple contacts in such close proximity, electrical conductive grease would certainly short out the circuit.

Inside the actuator you'll see the motor, 3 small gears and the large gear which drives the vent shaft to change the blend doors. Under this large gear is a copper flange with 2 fingers. The 2 copper fingers ride on the bottom of the circuit board on 2 metal rails. There are sections to the rails so it's easy to see the system is looking for conductivity in the different sections to either sense or set the position of the actuator. My actuator rails and copper flange/fingers were full of gunk/grease. I cleaned them both, wiped the other gears and put the actuator back together.

Once I cleaned the actuator, set it to a mid position, I put it back in the vehicle (right above the gas pedal). I used the reset procedure that I got from the GM dealer. (pull fuse, reinstall fuse, turn key so system has power and wait for a minute or so for calibration) I pulled the HVAC 10 amp fuse in the fuse panel under the hood. Re-installed the fuse, and the stuck my head under the dash to watch the actuator while I turned the key on (1 click short of engaging the starter to get power to the climate control board and fans). I was able to see the actuator move all the way to 1 side, pause, then move all the way to the other side, pause, and then end up somewhere in the middle. Before I cleaned the actuator, I also tried this procedure, but the actuator would only go to one side, and stay there. I'm guessing there wasn't enough connection to give the climate control board any feedback on what position it was in. I waited another minute or so to ensure the sensing of the actuators was complete, and then started to play with the different fan settings and vent positions. Everything was then working as it should!!!!

I'm guessing that most people who indicate they have climate control issues after a battery going dead, or battery replacement as I did have the exact same issue. When the system re-calibrates after power loss (battery change), it moves the actuators in their full range of movement. If there is grease somewhere along that range, I'm guessing it screws up the calibration and **** - no actuator function. The more I think about it.. the more sense it makes.

If I took this to the GM dealer, there is no way they would clean the perfectly good actuator, instead, I'd be charged a TON of labor and for a very expensive new actuator. Go Tahoe/Yukon Forum!!!

Problem Solved!!!

juicie · Jan 13, 2011

I need some help....I cant get the air to switch from face...I try to get the vent to blow on the windshield or the feet and it will not switch...not sure why

03LAYuk · Jan 21, 2011

Have to fix this today!

twbauer said:
FIXED!!!!!!! I can't believe it!!!

I cleaned the inside of the actuator as someone mentioned in some post I read. Ya know.. it really does make sense. If I know the motor runs when the system is calibrating, it's got to be something wrong with the "electronic sensing" of where the actuator is. It's easy to see that the goop/lubricating compound in there wouldn't allow an electrical connection on the rails, and should be cleaned up. I just used some paper towel on the end of a flat head screwdriver, and also just my finger. I also thought it may be conductive grease. I've seen that in some applications, but that wouldn't make sense either. With multiple contacts in such close proximity, electrical conductive grease would certainly short out the circuit.

Inside the actuator you'll see the motor, 3 small gears and the large gear which drives the vent shaft to change the blend doors. Under this large gear is a copper flange with 2 fingers. The 2 copper fingers ride on the bottom of the circuit board on 2 metal rails. There are sections to the rails so it's easy to see the system is looking for conductivity in the different sections to either sense or set the position of the actuator. My actuator rails and copper flange/fingers were full of gunk/grease. I cleaned them both, wiped the other gears and put the actuator back together.

Once I cleaned the actuator, set it to a mid position, I put it back in the vehicle (right above the gas pedal). I used the reset procedure that I got from the GM dealer. (pull fuse, reinstall fuse, turn key so system has power and wait for a minute or so for calibration) I pulled the HVAC 10 amp fuse in the fuse panel under the hood. Re-installed the fuse, and the stuck my head under the dash to watch the actuator while I turned the key on (1 click short of engaging the starter to get power to the climate control board and fans). I was able to see the actuator move all the way to 1 side, pause, then move all the way to the other side, pause, and then end up somewhere in the middle. Before I cleaned the actuator, I also tried this procedure, but the actuator would only go to one side, and stay there. I'm guessing there wasn't enough connection to give the climate control board any feedback on what position it was in. I waited another minute or so to ensure the sensing of the actuators was complete, and then started to play with the different fan settings and vent positions. Everything was then working as it should!!!!

I'm guessing that most people who indicate they have climate control issues after a battery going dead, or battery replacement as I did have the exact same issue. When the system re-calibrates after power loss (battery change), it moves the actuators in their full range of movement. If there is grease somewhere along that range, I'm guessing it screws up the calibration and **** - no actuator function. The more I think about it.. the more sense it makes.

If I took this to the GM dealer, there is no way they would clean the perfectly good actuator, instead, I'd be charged a TON of labor and for a very expensive new actuator. Go Tahoe/Yukon Forum!!!

Problem Solved!!!

Thanks for everything everyone has written on the subject. I need to fix this today and I'm totally frustrated. Our issue is not hot or cold air coming out when it's not supposed to, just a heavy "ratcheting" from the actuator on the driver's side. I can see the gear teeth up under there and it happens when switching from floor to dash air (of any temperature).

I've read tons of threads on multiple sites and forums including this one. I've tried all of the battery/fuse disconnect and reset fixes and none of them have worked. This "ratcheting" did not begin from a new battery, it just started on its own one day quite a while ago.

I don't know what else to do except try twbauer's cleaning trick here.....unless any of you have a better idea. I have no problem replacing the actuator motor if that's what's needed but after reading all of the posts I'm just about out of wits.

Any other last minute opinions before I tackle this? Thanks for your help.

Buggy · Jun 7, 2011

Thank You

I want to post a thank you for all the information that i found on this forum. You people saved me a alot of $$$. I replaced the passenger side blend door quite easily. I really appreciate the details and the pics that I was able to easily find. I hope I can return the favor someday.

Thanks again

04 Tahoe Z71

Blend door actuator or controller issue?

twbauer

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WHITEOUT

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twbauer

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WHITEOUT

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ilmk123

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WHITEOUT

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twbauer

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juicie

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03LAYuk

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