Blend door actuator or controller issue?

[alacran]

i had a problem like this also but mine would happen when its cold as hell outside. i wonder if your fix would work for me.

 

[JBeezy]

My driver side does this from time to time. I may try to pull this out today. Any pics of what I should look for?

 

[digitalfiend]

Step right up, get your pictures here!

I did this YESTERDAY on my 2004 Tahoe. The front driver side blend door actuator would intermittently misbehave, while the front passenger side was all hot all the time. I removed both actuators, cleaned them, reinstalled them, then calibrated them...after all this they are working great. This saved me a LOT of money since I haven't had to buy new actuators yet. The insides of the actuators look like this:



I suspect that the lubricant on the black semi-circular sensor is interfering enough with the actuator to cause it to not read properly, and in turn, get marked as faulty by the computer. Here's what the sensor inside the actuator looked like before being cleaned:



After cleaning the sensor this is what it looked like:

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!!!

 

[urbancafe]

This is really helpful and everything make sense. I got under the dash on both side. However, I was unable to locate the blend door actuators. Does anyone have a diagram or pictures?

 

[digitalfiend]

I don't know...but I know this guy who knows...

This is really helpful and everything make sense. I got under the dash on both side. However, I was unable to locate the blend door actuators. Does anyone have a diagram or pictures?

I didn't take any other pictures when I replaced mine. However, there's a whole set of pictures and instructions at sparkys-answers.com:

http://www.sparkys-answers.com/2009/09/2004-chevrolet-tahoe-blows-hot-air.html
http://www.sparkys-answers.com/2010/08/changing-recirculation-fresh-air-door.html
http://www.sparkys-answers.com/2011/03/2004-chevrolet-silverado-changing.html

 

[urbancafe]

I didn't take any other pictures when I replaced mine. However, there's a whole set of pictures and instructions at sparkys-answers.com:

http://www.sparkys-answers.com/2009/09/2004-chevrolet-tahoe-blows-hot-air.html
http://www.sparkys-answers.com/2010/08/changing-recirculation-fresh-air-door.html
http://www.sparkys-answers.com/2011/03/2004-chevrolet-silverado-changing.html

I found the first thread after more search. However, it only show the passenger side. Does anyone have picsl or diagram of driver's side blend door?

---------- Post added at 09:29 AM ---------- Previous post was at 09:04 AM ----------

Ok, now I am really confused. At the beginning of thos thread, it was stated that the driver's side blend door was located under the steering near the gas pedal. But when I re-read the info on sparky's, the driver's side blend ddooris on passenger side covered by the plastic piece.

So, which is correct? Also, if the driver's side unit is under passenger side, where is the unit controlli g the driver's side? I am having issues on both side. No air comes out to the face vents on both driver's and passenger sides, only thru defrost under windshield and bottom/floor vents.

 

[digitalfiend]

Ok, now I am really confused. At the beginning of thos thread, it was stated that the driver's side blend door was located under the steering near the gas pedal. But when I re-read the info on sparky's, the driver's side blend ddooris on passenger side covered by the plastic piece.

So, which is correct? Also, if the driver's side unit is under passenger side, where is the unit controlli g the driver's side? I am having issues on both side. No air comes out to the face vents on both driver's and passenger sides, only thru defrost under windshield and bottom/floor vents.

Props to you for going back and re-reading those links...the first one *should* have what you need. Here's what I can tell you for sure based on my recent experience:

In my 2004 Chevy Tahoe the driver's blend door actuator is in the same location that the first link describes: at the bottom of the dash on the passenger side covered by the plastic piece. I also had success at removing the passenger actuator based on the third link. I haven't yet had to work with the fresh/recirculation blend door actuator yet.


In hindsight, I didn't lay out the links as well as I could have, so let me take another swing at this:

Driver side blend door actuator: http://www.sparkys-answers.com/2009/09/2004-chevrolet-tahoe-blows-hot-air.html

Recirculation / fresh air door actuator: http://www.sparkys-answers.com/2010/08/changing-recirculation-fresh-air-door.html
(this is labeled part 2 and picks up where the "Driver side blend door actuator" article ends.)

Passenter Side blend door actuator: http://www.sparkys-answers.com/2011/03/2004-chevrolet-silverado-changing.html

 

[Cajun81]

Hey everyone. Just signed up. I just bought a 2002 Chevy Tahoe. The problem that I'm having is my air is fluctuating from all three destinations, one at a time. When I have it on ac and on face it blows just on there. When I put the heater on, it then fluctuates and no hot air blows out, just cold. Now when I have the system off but have the temperature on hot and the button pressed for the outside air coming in, hot air blows... I'm lost. Please help!!!!!!!

---------- Post added at 09:48 PM ---------- Previous post was at 09:35 PM ----------

I just noticed hat when the engine is running and the whole system is off. The beers at the bottom by the foot pedals is still moving back and forth.

 

[republicson]

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.

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!!!

About 4 years later, I'm about as giddy as you are. My 02 Suburban was stuck on "hot" in the front, so I replaced the relevant actuator. Nothing seemed better, but I hadn't worked through the reset procedure. I pulled the controls, blew them out, then put them back. Pulled the relevant fuses and put the back like you said, then let the car run for 60 seconds without touching anything. I felt it cycle through the different settings. Running great now! So happy to have A/C in mid-July.

 

[harveje]

"sometimes" cycling the key off to run position a few times has worked for me....
I can see the counts on the tech 2 but don't know if it's the actuators or the climate controller.