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2004 gmc envoy_slt
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56 Posts
Discussion Starter #21
Ok, lets finish this! =)

"Flush-fluid also works great in showing the marvels of modern chemistry, and how it is able to disolve/assimilate anything in its path."

you must be a star trek fan- Resistance is Futile.
LoL... I'm an uber-geek =P

Hi,
I can't say but excellent job done. Your photos are clear and in order. Thanks a lot for posting your experience in such a professional way. I had to praise the pro work.
Thanks! Just trying to add a little part to this HUGE community you guys and gals have here!

Wow! great work.
It definitely should be an article!:thumbsup:
Thanks! :)

Let us finish this one up... the delay was caused by a dog that ate my posts.

Here, re-written again :p

============================

Alright! Last time, we ended up removing the dashboard and disconnecting all the lines from the engine compartment side.

Now is a good time to "drop the steering wheel".
10.JPG

There are four big nuts that hold the steering wheel...
20.JPG

Once you do those, it is time for Popeye strength and some spinach.
If you are sure you have disconnected everything from the dash, you are going to have to pull HARD to get the frame out of its current position.
For around 20 minutes I thought I still had bolts holding it down to the chassis, as it was not budging at all.

Yet after making sure, taking a deep breath and some of that spinach, pull it out with considerable muscle, and everything just "pops" out.
It's a sign of relief when you don't hear any "I just broke something expensive" sounds.

Once you tug it out, I found it easiest to leave it "close to the steering wheel" while angled towards the passanger seat.
30.JPG
With the steering wheel down, it is easier for you to re-position the dash "frame" so it is easier to remove the HVAC box.

Once you have adequate space, remove the remaining nuts that hold the HVAC box down to the frame.
Here we have but three highlighted in green... there are various more nuts, a total of 8 I believe.
40.JPG



BRB with the remaining of the posts :)
 

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2004 gmc envoy_slt
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56 Posts
Discussion Starter #22
the Cold box...

In this next picture, you can see the nuts have been removed, and the HVAC box has actually been separated from the dashboard frame.
50.JPG

Now that you have an inch around the box to work with, you should remove all connections that go into/out of the box.
Those include; power for the blower, temperature sensors (lots of 'em!), vent-actuator control cables (name??), etc.

Take your time, and be patient with those clips.
It is better to treat them with some love at the moment, as they will be VERY useful when everything is getting put back together. Those clips enable everything to fall very neatly into place.

Once everything is disconnected, just take out the box.
It doesn't weight that much, so it is easily maneuverable.
60.JPG

And here is our lovely lady:
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Out and ready to get dis-assembled:
80.JPG


Because all of this was out, I found it very easy to clean everything.
I got a bunch of rags, cleaning solution, a bucket of water, and just wiped down everything.
I am really not interested into coming back into these crevices sometime later in my life,... so I'd rather clean it now. :)
 

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2004 gmc envoy_slt
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Discussion Starter #23 (Edited)
Open heart surgery... sort of

Now that we have the HVAC box out, we just keep on removing stuff.
There are two or three plastic clip things... yet there are like freaking 26 bolts holding that box together.

I just took my patience, drank some Acai Berry Juice, popped Michael Jackson into the radio, and started removing the bolts.
(( just kiddin' about the juice and about MJ :p ))
10.JPG
NOTE on the BLOWER:
I have read some very interesting studies about "blowers" from all things.
You would be amazed how a slight coat of dust on the blower 'blades' can affect performance.
Now is THE time to remove it, and leave it squeaky clean.
I used an old toothbrush (you can use a roommate's if you live in a college dorm) and a long-bristle brush.
NOTE#2 on blowers: The blower's blades have a little metal clip, visible here on the picture.
I am not 100%, yet I bank on this clip being there for the blower's dynamic balance.
Whatever you do, DO NOT REMOVE IT OR CHANGE IT FROM POSITION.
It was placed there by a very expense laser-guided machine designed by MIT students that decided to build such machine during the coffee breaks of their new super-safe portable nuclear power plant summer project.
Do not mess with the clip.



And we get to the heater core... which we didn't have to remove to replace the a/c evaporator.
Yet of course, I didn't know that at that precise moment in time. :)
20.JPG

The heater core is as good as new... it doesn't get much action down here.
With Puerto Rico being a tropical island and all...
30.JPG

So we snap back together the heater stuff, flip the box over, and keep on removing the other stuff.
40.JPG

It is very interesting the amount of engineering and thought that has gone into making such an HVAC box.
GM engineers are to be commended.
They have flaps, curves, galleys, tunnels, ducts and covers.
These are controlled with actuators that receive the info from who-knows-which-computer... all to keep you and Aunt Emma nice and comfy in your seat.

Thanks GM!
 

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2002 chevy trailblazer_ls
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27 Posts
Very nice and informative thread. I will be replacing my Evaporator sometime within the next 2 weeks and this will be very helpful. :thumbsup:

My AC would stay cold for about 2 days after getting it charged. The garage tried some of their stop-leak , but it didn't work. I got an estimate for just under $1200.00 to do the job, but almost $800.00 is labor.

I can also get the parts cheaper online , so now its time to roll up the sleeves and get dirty.....
 

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2003 chevy trailblazer_lt_ext
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I just want to take a second and thank the Original Poster for this EXCELLENT thread. I just used this guide to replace the Evaporator in my 2003 Trailblazer EXT LT, and this guide was a huge help. I was actually quite surprised at how exactly the Envoy matched the Trailblazer. There were probably only a handful of very minor differences, but all of the major points were documented perfectly in this thread. Thank you again OP and Trailvoy community. Without you, my TB and I would be much worse off!

Aaron
 

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2003 chevy trailblazer_lt_ext
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The one thing I would suggest doing differently for TB owners, would be to drop the steering wheel before you pull off the main dash cover. I had a very hard time trying to pull it over the steering wheel, and I was getting really nervous that I would break my blinker lever. When I put it back together, I left the steering wheel down until getting all of the main dash components in place, and it was much smoother.

Aaron
 

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2003 gmc envoy_sle_xuv
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25 Posts
Why so difficult to remove

It boggles the mind that GMC (and others...) do not make access to evaporators better! They know these things have high failure rates as they get older. To have to take the dashboard apart is insane. Thanks so much, though, though, for your documenting and sharing the experience.
 

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2002 chevy trailblazer_ltz
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42 Posts
Thanks!

Thanks for taking the time to do this write-up! It helped quite a bit when I replaced my heater core. You're a little more in-depth with the process than the manual, but not quite detailed enough to document every screw and bolt... so I have about 6 left over, haha!

Take care,

Brady
 

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2004 gmc envoy_sle
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1 Posts
Got the info I needed and was entertained along the way.

I just needed to find out where the clips were for popping out the panel with the Auto Headlight Sensor dome (detailer friend pushed it into the dash while cleaning the car, so all the lights were always on unless I remembered to push the knob left every time I restarted:(). The writing was so entertaining that I had to finish the entire instructional after getting my information. Well done, sir!
 

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2003 chevy trailblazer_ls
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19 Posts
Recirculation Acutator

Thanks to the OP for this thread... not much info out there on pulling the dash out. :tiphat

Dug this one from the dead because it helped me on changing my recirculation actuator which requires pulling the entire dash out and dropping the AC box down. Just wanted to add searchable key words and a couple of comments. :cool:

Couple things I did different for my situation:

1) I did not disconnect heater hoses or AC lines in the engine compartment. I wasn't changing the heater or AC core. I did pull the nuts off the seal plate in the engine compartment. This allows the lines to be easily pulled into the cabin by 4-6" to access top of AC box. I also disconnected the dryer mount on the coolant reservoir but don't think it was needed.

2) When remounting the metal dash skeleton get all the bolts in loose first. Don't forget the 2 bolts down by the back column mount nuts. I did disconnect the steel passenger side of the skeleton from the cast aluminum drive side when I dropped the AC box down. In the end it wasn't worth splitting the skeleton apart - don't recommend it and not needed... just turned into a pain in the ass to realign it.

Also, might want to have a can of 3M 77 adhesive and some 1/2" foam to R&R the foam seals that have dislodged and or disintegrated.
 

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2005 chevy trailblazer_ls
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11 Posts
If anyone is still around that has done this can you tell me where this bracket came from? I cannot figure out where it was attached to the dash frame.

55306
 
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