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2005 gmc envoy_sle
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80 Posts
Discussion Starter #1
Ya'll want to hear something CRAZY?

I d/c'd my battery about 7 months ago (as I always do) to clean my throttle body. After putting everything back together, my mode actuator stopped working, and I could no longer get the air to blow through the dash vents. I read these posts, and followed several of the tips to get it to reset, with no luck. I resigned myself to the fact that I was going to have to replace it. I had ordered the part, and had it sitting around, I just hadn't gathered enough patience to try and tackle it.

WELL, I bought a new stereo, and went about the process of installing it, stupidly, without d/c'ing the battery. Somehow, I managed to leave the blower running while testing out the stereo, and killed the battery. I mean, the battery was SO DEAD that I couldn't even get the gear shift to come out of park so i could move the truck close enough to the jump vehicle (I had parked it in the middle of my garage with no room for the other car). I ended up having to use my neighbors jump pack, got the truck started, and LOW AND BEHOLD, I suddenly had air blowing through the dash vents!

I don't know how it happened, but somehow, the actuator finally reset itself, and it is working perfectly now. I don't know if it's a fluke, or if draining the battery like that had something to do with it...but either way it's working now and I can't explain why.

i figured I'd throw this out there, in case there is some kind of correlation between my screw up, and a fix for this problem.
 

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2009
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1,088 Posts
One of the steps in troubleshooting is to pull the HVAC B fuse which will kill all power to the HVAC system. Turn off the entire HVAC system and then turn the key on. Let everything reset and t hen start it and try the HVAC system and see if it reset the actuators.

I think you accomplished the same thing by running the power down on the battery which caused everything to reset.
 

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2005 gmc envoy_sle
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80 Posts
Discussion Starter #4 (Edited)
No mystery, disconnecting the battery is one of the prescribed methods of reseting the actuator.


Sorry to rain on your breaking news story :crackup:

I'm not an idiot, I tried both of those tips mutliple times when it went out 7 months ago, with no success. I don't know, maybe i didn't try enough. Either way, it's working now :)
 

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2004 gmc
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26,181 Posts
The recalibration process takes a minute or minute and a half, so if you disconnected the battery, or pulled the HVAC-B fuse, and then put them back, then turned on the ignition, then waited 90 seconds for the recalibration process to complete, all seven months ago, then you did it all properly for sure. :thumbsup:

If you got a clicking actuator, that we've usually found to be a broken plastic gear tooth and that doesn't recover. :sadcry:

If you had an intermittent position feedback potentiometer, that could possibly heal itself especially if the temp is different now than it was seven months ago. :woot:

We'll add the following step to the troubleshooting flowchart:

Pull the fuse or disconnect the battery ... blah, blah, blah.
Buy the replacement part.
Wait seven months then drain the battery and see if the actuator comes back to life.
If it does, you win, but you just wasted seven months without heat (if winter) or AC (if summer).
Don't hate us. :dielaugh:
 

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2003 gmc envoy_slt
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7 Posts
Actuator help

SO I disconnected the battery on my 2003 Envoy and waited more than 90 seconds. connected it and saw that the actuator did a little moving (as usual) but the AC did not blow from the top vents. Where is this HVAC fuse B?

I also looked for a part number on my actuator and this is what I found;

52495907
and
43322034A

I research both of these in Google and several other sites and got DORMAN 604110 as a replacement. Is there a way to confirm these part numbers are actually what I need in case I end up buying the part?
 

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2003 gmc envoy_slt
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7 Posts
Actuator Location and Part Numbers

Thanks for your reply. I took a look and none of those part number match what is on the actual actuator. On the sticker there is are two numbers
TOP number is 52495907 and bottom number is 43322034A.

Looking at the location on the diagrams I see Air Flow Mode Actuator as the part I need. AC DELCO part is 15-73596 or GM Part 89018675.

I just want to make sure I order the right part before I take it all apart. Right now afternoons in HEll Paso, TX are kinda hot...
 

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2003 gmc envoy_slt
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7 Posts
Mode actuator Update

Found the fuse under the rear seat on the driver side. Disconnected the battery, pulled the fuse waited about 15 minutes, inserted fuse, reconnected the battery, turn switch to on and turned AC/blower to off and waited 5 minutes. Tried the AC vents on top and did not work, did it 5 more times and no dice, did not work. So I manually turned the switch and disconnected power into it to avoid getting it reset to the lower vents again.

I am going to Autozone in the afternoon and will try to tackle this tonight. My biggest concern is getting the correct part. None of the Autozone P# numbers match anything
 

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2003 gmc envoy_slt
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7 Posts
Changed Actuator Once

So I go the actuator form my local parts store and took the old actuator off. Now this is where I have been for two days now; I take the old actuator out, put the new one in and recalibrate as suggested in several postings here. Turn AC back on and the vents are stuck in the Low vents. I press the mode button and nothing changes.
One thing to note is that when you take the part out the vents automatically drop to the low position. The only way I have been able to maintain the vent in the top position while I install the new part is by turning the AC on manual turning the gear that actuates the vent to on and putting in the new part.

I need to know in what position does the vent need to be when you install the new part.

The complete change of the part is no more than 30 minutes, the problem I am running into is that after recalibration sequence, the vents continue to be stuck in either top or bottom vent position
 

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2004 gmc envoy_slt
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2,323 Posts
Maybe its not the actuator. I am dealing with this on my daughter's truck on the driver's side temp control. New actuator did not fix problem, have ordered a AC control panel. Hope that is it.
 

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2003 gmc envoy_slt
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7 Posts
HVAC Mode Actuator (READ INSTRUCTIONS FIRST)

Figured I posted an update since I final got the mode actuator fixed. Turns out that I needed to read the enclosed instructions in the box the actuator came in. On the night I worked on the 1st actuator I had an itch to apply power to the new actuator before mounting it DO NOT DO THIS :nono: . Mounting instructions clearly state to not but of course I had 10 cups of coffee and it was 1:00AM when I was doing this so I did not read them.

I got another actuator (They have warranty on them) and followed the instructions outlined here;

1. Took apart bottom dash plastic piece and set it aside.

2. Disconnected Battery (Both Posts).

3. Removed HVAC Fuse (Located under rear seat) passenger side.

4. Changed old actuator with new one. I did not have problems aligning this like most people have mentioned. Just wiggled it in and mounted in place.

5. Connect harness to new actuator.

6. Install HVAC Fuse

7. Connect battery posts and waited 5 minutes until everything settled under dash.

8. Inserted Key and turn to ON position NOT RUN. and turned off blower to allow a smooth recalibration of the new actuator. I waited 5 more minutes just to be sure.

9. Sat in driver seat and took a sip of my coffee, turn on the truck. Turned the AC on and air was blowing out of the top vents, switched modes and they worked as they should.

Please read directions before mounting this commonly replace part on our vehicles, it will save you many hours of senseless work.

:thx
 

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Registered
2007 chevy trailblazer_lt
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259 Posts
:iagree:
Figured I posted an update since I final got the mode actuator fixed. Turns out that I needed to read the enclosed instructions in the box the actuator came in. On the night I worked on the 1st actuator I had an itch to apply power to the new actuator before mounting it DO NOT DO THIS :nono: . Mounting instructions clearly state to not but of course I had 10 cups of coffee and it was 1:00AM when I was doing this so I did not read them.

I got another actuator (They have warranty on them) and followed the instructions outlined here;

1. Took apart bottom dash plastic piece and set it aside.

2. Disconnected Battery (Both Posts).

3. Removed HVAC Fuse (Located under rear seat) passenger side.

4. Changed old actuator with new one. I did not have problems aligning this like most people have mentioned. Just wiggled it in and mounted in place.

5. Connect harness to new actuator.

6. Install HVAC Fuse

7. Connect battery posts and waited 5 minutes until everything settled under dash.

8. Inserted Key and turn to ON position NOT RUN. and turned off blower to allow a smooth recalibration of the new actuator. I waited 5 more minutes just to be sure.

9. Sat in driver seat and took a sip of my coffee, turn on the truck. Turned the AC on and air was blowing out of the top vents, switched modes and they worked as they should.

Please read directions before mounting this commonly replace part on our vehicles, it will save you many hours of senseless work.

:thx
 

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2006 chevy trailblazer_lt
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2 Posts
2006 trailblazer lt

I have the problem of no air out of the forward facing vent in the front dash. i took some of the panels off and was going to replace the actuator but could not get a vent tube out of the way. it is u shaped around the gas pedal. do i need to take the pedal off to get the vent duct out so i can get to the actuator?
 

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2007 chevy trailblazer_ls
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5 Posts
Old thread but maybe this will help someone.
After doing the recalibration 4 times with no luck, I decided to turn the key ON while the battery was disconnected. Maybe drain any residual magnatism in the motors. Did the routine once again, calibration ran about 3 times as long and pop everything worked as normal. Go Figure ?????????
 

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1 Posts
My 2003 GMC ENVOY SLT IS NOT LETTING THE AC DO ITS JOB BY BLOWING THROUGH THE FRONT VENTS AFTER WE CHANGED THE SPARK PLUGS AND FUEL FILTER. TRIED TO RECALIBRATE IT 4TIMES WITH NO SUCCESS . DONT GET HOW OUT OF THE BLUE THE ACTUATOR SCREWED UP ??!! IM IN LAS VEGAS SO AC IS A MUST SOMETIMES 🔥
 

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2002 chevy trailblazer_lt
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174 Posts
Here is what happens. Disconnecting the power to the system forces a recalibration. To recalibrate, the system runs the actuators in both directions until it senses the end of travel. The plastic gears are brittle with age and cannot take the force of hitting the end of travel and they crack or break teeth.

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