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2002 chevy trailblazer_lt
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Discussion Starter #1
i just bought a 02 tb LT with the I6 in it and didnt notice the problem with the hvac.. wouldnt have bought if like that if i knew and unfortunately it was (as is) so.... yeah i gotta fix this and am not paying a deal or mechanic to do something i can do with the right info. so i been looking thru the threads trying to find the same problem as mine and ive come close but not exactly. i also have heard the clicking sound when in the hvac is turning on or off. i pulled apart the pieces to the glove box to access the passenger air actuator valve. i removed that and took it apart to see maybe if there was a dead spot but it seemed to be ok except the metal piece was corroded slightly but not with rust. i started with the fuses and didnt make any progress and cant find out what this "trick" is to resetting the temp actuators. i started with the pass. side because the driver seems to be good im guessing that my next stop will be ordering a new passenger temp actuator and seeing if that will fix the bad line in the whole hvac system. if i am assuming to much would appreciate it if anyone could pass along some info. also when i pulled out the pass. actuator i could see the rod that opens and closes the valve but am not sure how it works. turned one way i believe that it only allows heat from the engine and turned the other way is climate controlled but there is no "control" so this is why i think it must be the passenger temp actuator. as mentioned earlier "climate control" only "controls" driver vents, rear vents blow but not with a controlled climate. also the rod that the passenger temp actuator controls, when i turned that by hand and cut off the cold air it was replaced by hot air. its getting really cold outside so that really helped supplying time to make a good buy to fix this problem.. kinda shaky about buying this truck even tho i love the way it drives, the power, the 4wd it has everything u want but most likely the source of all the problems everyone goes thru. Also tomorrow i will be cleaning the throttle body becuz the truck doesnt always like to stay running when switching the the HVAC system so we'll see if that changes.... one last thing if anyone knows how to fix the remote keyless entry system please let me know i tried replacing the battery and holding both buttons close to the sensor but nothing happened.. my 1st post... and its long but ill have more once i make more progress thanks!
 

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2002 chevy trailblazer_lt
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5 Posts
Discussion Starter #3
passenger side actuator

I puller apart the passenger actuator to inspect and all looker good and I could see it working when I played with it. To get heat out of the passenger vents I turned the valve that the pass. actuator controls. This actuator only wants to turn on and rotate one way no matter what settings I have the hvac on. My hope is that the actuators work on a circuit therefore replacing this passenger side actuator will allow the passenger and rear climate control to work. Also cleaned the throttle body and now no stalling maybe looking into the performance throttle body.... I looked thru threads and can't find out how exactly to reset the hvac via pulling fuses.. anyone who would pass along some insight it would be appreciated thanks
 

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2004 gmc
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26,181 Posts
I puller apart the passenger actuator to inspect and all looker good and I could see it working when I played with it.
OK, so far.
To get heat out of the passenger vents I turned the valve that the pass. actuator controls.
Good.
This actuator only wants to turn on and rotate one way no matter what settings I have the hvac on.
Didn't you say in your first sentence that the actuator looked good and worked? :confused:
My hope is that the actuators work on a circuit therefore replacing this passenger side actuator will allow the passenger and rear climate control to work.
Wish you could be a tiny bit more detailed in your description. When you say "allow the passenger and rear climate control to work." do you mean that you have no control over the airflow or temp of of the rear? The Owner's Manual has the detail that the passenger temp control up front (on a short wheelbase vehicle, not the EXT/XL) also controls the temp coming out of the rear vents in the console. The rear seat passengers get their AIRFLOW from a separate fan speed control in their area of the console out back.
Also cleaned the throttle body and now no stalling maybe looking into the performance throttle body.... I looked thru threads and can't find out how exactly to reset the hvac via pulling fuses..
Rear fuse #36.
 

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2002 chevy trailblazer_lt
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Discussion Starter #5
ok well apologies for not being more detailed.. so let me better explain my situation. i pulled apart the glove box to access the pass. temp actuator. after inspecting it and concluding power seemed to be getting to it although not sure the right signals were being sent from main digital climate control, not sure what u wanna call it anyway, i noticed the head of the rod that the pass. temp. actuator grips and controls so i turned it manually. i did this with the air on hi and low. it seems to cut off the hvac inlet to the pass. vents. i say that because when i turned it from its original position the air was blowing half as hard but i was just happy to feel heat. let me be clear that it was not "controlled" air. I tried running it thru different modes, temps, and no change just hot air i believe comes from the engine bay. now if i turn the valve/rod back then the cold air comes blasting out definitely colder then the outside air, and it comes out almost twice as hard as the driver vents.

Ok now on the rear vents this what i gathered.. before and after messing around with the passenger temp actuator and the valve it controls i tried to control the temp of the rear vent floor and roof. only result is cold air. all the air speed controls in the truck work fine just the temp control on the back vent and also the passenger vents.

I have the 2002 ext four wheel drive Lt i6 loaded if that helps any.

also im about to buy a performance muffler. i cut off the baffle on the end and replaced it with a resonated tip. saddly i have to say that it doesnt sound like the video i watched where the guy supposedly did the same thing. i have a replacement specter air filter on the way hoping that it will help. im looking for better gas mileage but now it sounds like a little honda with a some what quiet exhaust on it. like i said im looking to buy a muffler to replace the stock one but could use more insight before doing so. i appreciate everything you've done thanks for ur help
 

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2002 chevy trailblazer_lt
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Discussion Starter #7
i need to know how the system works for the hvac. does it run on a circut? if i fix the pass. temp. actuator could possibly the rear work? i think one thing for certain is i need to start by replacing the passenger temp actuator what would u think?
 

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2004 gmc
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All electrical things work with circuits. If you mean are the front and back actuators interconnected in any way, then no. They're independent problems. I can't find the front schematic at the moment, but they theory of operation is the same. The motor gets commanded by the control module to move, and it reports its position back by way of the sensor wire which is essentially the wiper of a potentiometer. After you pull the fuse and reset the memory of the control module, it needs to recalibrate all actuators by commanding them full CW and CCW to see where the doors they're attached to have their physical stops.

You might consider buying the Haynes manual or getting access to the AlldataDIY data base.

Here's the back:

 
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