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2005 Suburban A/c Blows Hot On Driver's Side.


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#1 Beebe

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Posted 15 July 2009 - 08:19 PM

Hello all, I am new to the forum. I have found a wealth of info so far, and decided to join. I realize similar questions on this issue have been posted, but I needed some clarification on some points.

My wife and I just bought a 2005 Suburban last week. The battery was the original, so I swapped it out last Sunday. Pretty easy thing to do, but now we have problems. We have digital dual climate control, and the driver side is blowing hot air. The passenger, and rear are working fine. I have done alot of research and have come to the conclusion it may be the blend door actuator. I have followed some "re start" (remove HVAC/ECAS fuse) procedures and it seems to calibrate and starts blowing cold air, but ends up blowing hot.

The questions I have are as follows. What I don't understand is it was working just fine, until I swapped batteries. How can it all of a sudden be "faulty"?
I have seen the diagrams to remove and replace the actuator, and the re-calibration steps. What I need is clarification on something. Is the HVAC Control Module the same as the blend door actuator? If I replace the blend door actuator what do I have to reset it?

Thank You

#2 bill190

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Posted 15 July 2009 - 09:24 PM

Might try removing the battery connector for 10 minutes.

Then start the vehicle and don't touch the A/C controls for 1 minute...
http://74.125.93.132...N...=clnk&gl=us

Other than the above and if no one else has any things to try, best to get a GM factory service manual set for these types of problems (order from GM dealer of helminc.com).

This would have detailed troubleshooting instructions and instructions for replacing parts if necessary. Some of these things need to be replaced in a certain "sequence" so things are "synchronized".

#3 Beebe

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Posted 15 July 2009 - 09:34 PM

Thanks. But is the HVAC Control Module the same as The blend door module?

#4 bill190

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Posted 15 July 2009 - 10:10 PM

These things are different from year to year.

Generally an HVAC control module would be an electronic control unit. In newer vehicles this would be a computer module with its own diagnostic codes and would be able to communicate with other computer modules in the vehicle over a computer "local area network".

With those in the newer vehicles, a GM dealer can connect to the vehicle and read diagnostic information for these various computer modules. You need a special scan tool for this.

Then a door module so far as A/C goes is a electric motor basically which would move a door (damper) open, closed, or anywhere in-between.

And with an automatic dual temperature system, there would be all sorts of little electrically operated doors which control this and that.

And these are probably not "smart" doors/motors. The computer may be working "blind" to control them. They need to start out at a set position, then the computer would tell the door to move so far a certain direction. The computer would have no idea where the door actually was or if in fact it moved to where it should have.

So that is why the calibration is important above. The computer may tell all of these electric doors to move all the way one direction. It then would "know" where they are all located and then be able to adjust them as directed.

For example a door (damper) might be able to move to open, middle, or closed.

And the computer could control it to move to open middle or closed.

But say the door is at the middle.

And the computer thinks it is at open.

Then the computer gets a command to move the door to middle and it moves it to closed instead! (Not knowing any better!)

#5 yfrankiii

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Posted 05 August 2009 - 01:57 AM

I have 2005 Chevy silverado, same as GMC Sierra with dual climate control. I was getting hot air on drivers side but Passenger side was cold. I was also getting air only out of the defrost vents. I had to change battery for other reasons but noticed after I disconnect batteries, (2 for diesel) the air now worked in the front vents.....odd...but perhaps just needed to reset position on door flap but that only lasted a litte while and again had same problems. Anyways, took to dealer, said I need left side temperature door actuator and recirculation actuator per their trouble codes, wanted $290 for each actuator, each is the same part number. and another $460 for labor, over a thousand dollars. Researched internet and found someone had removed actuator and open it up, cleaned grease off the contact and circuit board and it worked for them. I figured worth a shot. I removed the actuator on the drivers side, right behind and above the gas pedal. I removed the actuator by removing two screws bottom and top. There is a backing plate or actuator plate that is a large half circle shape with small geared edge and two channels cut out in upper edge. Remove plate with actuator. Mark the location of actuator in reference to the plate. with actuator removed and unplugged i started engine and turned on AC. Move the white gear that was attached to the gearing on actator plate manually and see if cold air now flows to vents on drivers side. Mine did. I took apart actuator with small flat screwdrive and small pick to open clips on all sides. nothing springs apart. just remember how gears fit together, I removed gears and used q-tips and some alcohol to clean off contacts and board, You will see a split contact on black piece that backing plate locks into. Clean contacts and the bands they rub on. with gears out, i checked with 9 volt battery with small aligator cips to see if motor spins, reverse polarity to test both ways. Before you pop the cover back on, make sure the actuator fits into the backig plate in the same position. I had to take mine apart again because I didnt have the geas lined up to be in same position for alignment with backing plate. I have to slip gears out and move the black gear on tooth over so it lined up the same as before taking apart. Mine worked so I reassembled and re installed. INstallation is a pain. found with engine running and ac blowing i could move white gear on HVAC unit towards the back of car or and since its blwing the vaccum holds it in that position, same as the small knob to the front on the that needs to be pushed up to move another flap inside the HVAC unit. With those in place, put actuator plate back up against HVAC unit, one curved slot for where screw goes into a small tower hole and knob that you pushed up goes into outmost channel slot and white gear matches up to geared area on plate, Be careful, on back of white gear there is small knob that needs to slip into channel slot on backing actuator plate then press plate flatly against the HVAC unit. You can then slip on actuator unit into the spot that you marked previously to line up with backing plate. Screw in screws. Shut off engine prior to hooking up wiring. then restart and hopfully like mine...that wil work for you too. saved me a $1000....

#6 bill190

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Posted 05 August 2009 - 09:04 AM

That's the way to do it! Good post.




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