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2004 chevy
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21 Posts
actuator gear

Well I took the actuatar apart. The teeth are fine but I did notice the big gear was not pressed on all the way and was out of place. I tried to aline back in place. I did the recalibrating and it found both end points this time. I tried the control head a few minutes later and It was not responding. I tried reposition the gears in the actuator and had not luck. I ended up breaking a gear in the process. I guess I am stuck getting a new actuator. In the mean time I used a wire to pull the vent door down manually to get windsheil and feet for the winter. To reverse, I just shut the air off and let the weight of the door fall back to the front vents. It was a good idea untill the wire popped off. It was worth the shot.
 

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2004 chevy trailblazer_ls_ext
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814 Posts
Use a shoe lace... lol...

Well I took the actuatar apart. The teeth are fine but I did notice the big gear was not pressed on all the way and was out of place. I tried to aline back in place. I did the recalibrating and it found both end points this time. I tried the control head a few minutes later and It was not responding. I tried reposition the gears in the actuator and had not luck. I ended up breaking a gear in the process. I guess I am stuck getting a new actuator. In the mean time I used a wire to pull the vent door down manually to get windsheil and feet for the winter. To reverse, I just shut the air off and let the weight of the door fall back to the front vents. It was a good idea untill the wire popped off. It was worth the shot.
 

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2004 chevy trailblazer_ls_ext
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814 Posts
so I replaced my actuator last night, it was kind of a PITA... couldn't get the actuator to align, finally I saw there was a notch, pulled the fuse, and observed as it went through its calibration, shut the power off once it was aligned... moved the vent door gear so the notch on the gear would be parallel with the mounting holes and whala... installed, pulled the fuse once again, and went through its calibration process once more and finally finished... took me about 1.5 hours... granted I spent about 30 minutes trying to take out the floor duct... couldn't get that plastic plug out.. didn't want to yank on it and accidentally breaking it... :) ....:woohoo:
 

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2003 chevy trailblazer_lt
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12 Posts
Front Vents not Blowing

I had the same problem after replacing the battery on my 2003 Trailblazer the air would not blow air out the dash vents when on AC it would only blow cold air out the floor vents. I tried the whole routine of pulling the #36 HVAC B fuse and that did not work using the procedure mentioned in another post. Then tried disconnecting the battery cables again and tried to get it to recal with no luck.
I then proceeded to pull the driver side dash apart and was able to get my hand on the Mode actuator and it would not move. I could feel it but could not see it. I then pulled the electrical plug on the operator and moved it manually with a penny in the shaft slot to vent to the dash. This worked fine until I plugged it back in but it returned to vent to the floor. I then unplugged it again and manually moved with the penny to vent out the dash and it works fine now since we need AC here in Florida and not heat, mostly AC but there have been periods of cold here were you need heat.
As I said could only feel actuator and not see since I didn't have a short extention for the socket wrench to pull the bracket that holds part of the center of the dash. If I had of pulled that bracket I believe I could have seen it.
My plan is to order the mode operator and when I have the rest of my tools plan to replace the Mode operator as that appears to be the problem.
All I can say is what a poor design that causes you to replace parts just because after 6-1/2 it was time to replace the battery and now the heater AC parts need to be replaced due only to that??.
 

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2004 gmc
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All I can say is what a poor design that causes you to replace parts just because after 6-1/2 it was time to replace the battery and now the heater AC parts need to be replaced due only to that??.
We agree totally. The design team must have been packed with noob interns without adequate adult supervision, is my analysis. :hissy: Way too many dumb mistakes that an experienced engineer would not have made. :bonk: The GMT360 ends up with a bunch of now-orphan pieces that can be used as examples of how NOT to design a platform. :rolleyes: If only somebody wrote a book and the engineering schools used it as a textbook and the students actually read it and absorbed the lessons. :hopeless
 

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2004 chevy trailblazer_ls_ext
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814 Posts
Seriously, you should school all the wanna be GM engineers... changing this actuator cost me valuable time and a few drops of blood...:crackup:

BTW, thanks Roadie for the diagram... :)


We agree totally. The design team must have been packed with noob interns without adequate adult supervision, is my analysis. :hissy: Way too many dumb mistakes that an experienced engineer would not have made. :bonk: The GMT360 ends up with a bunch of now-orphan pieces that can be used as examples of how NOT to design a platform. :rolleyes: If only somebody wrote a book and the engineering schools used it as a textbook and the students actually read it and absorbed the lessons. :hopeless
 

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2006 gmc envoy_sle
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1 Posts
front vent problem solved

I tried all reset options given by the forum member, but all were failed.
fiNALLY I change the "Mode Actuator" and everything becomes fine.
 

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2002 chevy trailblazer_ltz
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9 Posts
rear climate control

hello specially to the roadie i know this thread is old but in a series of attempts to fixing my vent problem i pulled the rear havc fuse and now it wont select between floor and upper vents this on the rear, air does come out but is not cold enough and also the diagram showed from the dashboard has message and it really cant be seen clearly where can i download that? but back to my problem i want to move by hand temperature 'door' and the selector 'door' also so i get cold air from the upper vents for both the drive and passenger side i need to know how to get to those but please no guessing i need to know how its very frustating now that s being 108 degrees here in vegas and on top of that i have a 6 month old girl please this is urgent i need to move by hand both vent and temp door to keep them lock where i want i dont care if i have to disconect them so that they dont move any more and how do i make cold air blow through the back climate control vents thanjks a lot:):thx
 

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2006 chevy trailblazer_ls
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3 Posts
a/c vents not blowing

I had this problem and thanks to this site, I was able to narrow it down to my mode acutator not working. I fixed it without any new parts. I have an 2006 trailblazer with manual controls. I pulled the lower dash and black panel below off. Just a couple of bolts 7mm I think, two below the steering wheel have plastic covers. You need to pull that rectangular long curvy foot vent on the driver side under the dash out they way. It's held in by one plastic pin on the door side that just pops out and in, so pull it down from the door side and don't be afraid. Then when laying down under there you can see 3 black acutators. The one by the firewall is for the window defroster and floor vents. The one next to that is for the main vents. Not sure what the one close to the steering wheel is for. Pull the HVAC fuse under the rear passenger seat out for 30 secs. and put in back in. Put the key in the ignition, but DON'T TURN IT YET. Lay back down and then turn the key. You will see the silver slotted gears on the actuators reset. My main vent was not moving, problem found. I took it out, with some patience and a 7/32 socket on a small screw driver, it also has a connecter the you just press and pull out. Don't drop the screws. It has a white gear attached to it that can be pulled out. Remember the postions. Then after going to buy one, I got the wrong one and had to return it. The only store around with it in stock was NAPA and they were also the only ones that closed at 5:00. So I thought I would have to wait a day, and then decided to look inside the actuator. While closed I could not turn the gear. I opened it and saw all the gears and the motor. I pulled the motor out and the gears could all turn, bad motor right, wrong. I put the motor back in and pressed all the gears. the small green one attached to the mother board went down and was not connecting with the big gear. I raised it a little and decided to give it a try. Hooked it up with out putting it back in, did the reset again and it moved but then stopped. I disconnected it and opened it again. That same gear was down again. This time I put it up as high as it could go, put the cover on gently and flipped it upside down, then snapped it in place, so I wouldn't vibrate the gear down. I put the white gear back in and had to hook it up and let it run a little, then stop because it was all the was to one side and wouldn't line up, screwed it in and was back in business. Everything worked. This may not work for everyone, some have said their gears were broken inside. Mine were fine, just the one with the motherboard slipped.
 

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2007 chevy trailblazer_lt
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1 Posts
Ac not working at all

I had paid someone to change out my factory stereo in my 07 chevrolet trailblazer. When i left i tried using my a/c and nothing was blowing out of the vents at the top. I've tried getting a new a/c control module, replaced it and it still didn't work at all. I disconnected the battery along with the hvac fuses for 30 seconds. Put the fuses back in and started my car and still no luck at all. I then waited for about 2 mins to let it recalibrate on its own and still no luck. I cant seem to find out what the issue? Anybody know what i can do to get some a/c or heat to work in my top vents. My bottom vents work just fine for heat but no a/c. My rear doesnt work at all either. What other things could i try to get my a/c blowing back to normal?
 

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2003 gmc envoy_sle
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4 Posts
Dash Vents Won't Blow Hot or Cold

My car is a 2003 Envoy with around 140K miles

You have probably read a lot of other posts by the time you get to this one, so I won’t go into a lot of detail that’s already been hashed over. My A/C wouldn’t blow through the dash vents, no matter where the mode selector switch was set. (The mode switch is the one that selects which vents heat and air blow out of.) The vents are controlled by actuators which are just small motors that open and close various doors that determine where the air goes. Like many of the posts, my problem occurred when I reconnected the battery after storing the car for 6 months.

From all the previous posts, I figured the mode door actuator had failed. You can try the recalibration process included at the end of this blog and it might correct the issue. I tried it numerous times but although the actuator moved, it would only go one direction and then stay there. An optional double check would be to take the car to a GMC dealer and have them run a diagnostic check. My diagnosis showed code “B0263, mode door actuator stuck”. The cost was $65 but I knew for sure I had the correct diagnosis. Quote for the dealer to make the repairs, $528.

I pulled the two dash panels on the driver’s side under the steering column, the silver crash bracket under the column, and the plastic vent that routes air over to the driver’s side. Tip: Be careful when removing the plastic vent push screw because the bracket is fragile and easily broken. You need a 5.5mm, 7mm, and 10mm sockets to remove this stuff. Looking up under the dash above the gas pedal, you will see two black actuators. The mode door actuator is the one farthest from the firewall. Ordered the actuator from Amazon, AC/Delco Part #15-73596, GM part #89018675, for $43. Removed the failed actuator with a 5.5mm socket…..two screws hold it in. A little tricky getting at the back screw. If you want to test the system to make sure air comes out of the dash vents, reach up and turn the actuator gear fully CW. When you are ready to install the new actuator, turn the gear on the door(not on the actuator) by hand to about the mid-point in it’s travel. The white actuator arm has a notch that mates with the door gear so there is only one way it will fit. You may have to do a little back and forth to get the notch and gear to align. Then hold the actuator in place while you get the screws started and tightened down.

Now for the big test. Lots of previous posts on making sure everything is calibrated. This calibration procedure worked for me: Ignition off, A/C off, blower switch off, remove fuse 36(or disconnect the battery), wait 2 mins, insert fuse 36(or reconnect battery), ignition two clicks to run but don’t start, wait 2 mins, start car, turn on A/C & blower, test mode switch. Everything should work now.
 

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