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2002 chevy trailblazer_ls
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Discussion Starter · #1 · (Edited)
Hey everybody, new member here.
I originally joined up to be able to see the pics on how to replace the heater core on my sons 2002 Trailblazer. And after starting the procedure, I thought that with a few modifications,
it should be possible to R&R the heater core without dash, vent system removal, and A/C system discharge and recharging...

And it can indeed be done.
And this is how I did it.

First, all that has to be removed is the instrument cluster/radio trim bezel, the radio and ventilation control panel, the dash center support bracket, center console, the heater core lower cover, and the floor vent ducts.
Now of course to remove the trim bezel, the panel below the steering column has to be removed to get to some of the bezel retaining screws.

Once these parts are out, some of the dash fiberglass material behind the radio/vent control panel has to be cut out in order to be able to remove the dash/ventbox support bracket.
Part of what gets cut out has to reinstalled in order to support the back of the radio.
This pic shows part of what was cut out, and kept for the rear radio support.
More below this piece was also cut out.
Just be sure you don't cut through any wiring...
You will also notice I added a second 7mm screw to the radio support piece, just to strengthen it up a bit.

 

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2002 chevy trailblazer_ls
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Discussion Starter · #2 · (Edited)


This is the support bracket removed from the dash. There are two bolts at the bottom that attach it at the bottom to the shifter bracket, and two at the top that attach it to the ventbox support, as well as the one bolt that attached to the dash fiberglass.
Again, you can see the 7mm screw I added just to the right of the original 10mm bolt.
 

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Discussion Starter · #3 ·






These show the cutting done, and the bracket removed.
The radio had a theft code set, and my son didn't know what it was, so I left the radio plugged in to keep it from locking up. Fortunately, I was able to pull enough wire out to lay it in the seat while still plugged up...
 

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Discussion Starter · #4 · (Edited)


Here you can see two of the 5.5mm screws that hold the heater core lower cover on.
There is a third screw that can be accessed through this opening, just to the left.
There are 13 total screws, IIRC.
There was also a 10mm nut and stud that attached the lower heater core cover to the support bracket. This was unnecessary IMO, so I cut it off of the cover, once removed...

You can also see that wiring harness retainer also has two clips that attach to the support bracket.
I chose to cut them off. The harness isn't going anywhere with, or without them...
 

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Discussion Starter · #5 ·


This shows the lower heater core cover, cut into three sections to make reinstallation much simpler. The heater core is shown laying in the box just for reference.

This cover is a real bear to get out from under the dash in one piece, so it would be even worse to get back in there without cutting it into these three sections.

The far left piece covers the heater core tubes going to the firewall.
The center piece goes to front, next to the firewall. Notice where the four screws are located in this piece. They are very difficult to get at, and see.
This piece can be reinstalled right after the old heater core comes out, and will not have to be
removed again another heater core has to be installed...
 

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Discussion Starter · #6 · (Edited)


Old heater core coming out.
The heater core is supported in the upper housing by a retaining clip at the lower front of the upper box.
Just wiggle and pry on it til it pops out...
 

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Discussion Starter · #7 · (Edited)




This shows the front part of the heater core cover reinstalled.
The floor ducting attaches back to this after the heater core and covers are back in place.
You can also see the heater core retaining clip here as well.

The carpeting and padding was already cut on the drivers side, and was pulled out of the way.
Don't know if this was a factory cut, or if someone had done it previously...
You'll also notice I cut out a piece of the firewall padding to get easier access to the four screws that are against the firewall.
 

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Discussion Starter · #9 · (Edited)


New heater core in place.
Getting it onto the reataing clip might take a few tries.
I used a small screwdriver to pry the clip tabs down a bit, to get them
to latch onto heater core lip.

Now just install the lower core cover, the tube cover, and all the other stuff that came out.
Even with the lower cover in three pieces, the main core cover is still a little tight to slide back in place,
but it will go with just a bit of patience...
The two screws on the sides of the cover are pretty tough, as the center part of the dash makes them
pretty tough to get at.

You'll also notice that I removed the glovebox, but it isn't necessary or helpful to do so.
 

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Discussion Starter · #10 ·
Thanks for the great write-up. It will make a good reference for anybody tackling the job.
Thanks.
I just wanted people to know there is an alternative to tearing everything out.
If you are willing to do the cutting mods, it can save a lot of work, and even more if you ever
have to do this job to the same vehicle again...
 

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2004 chevy trailblazer_ls
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Heater core

Well, I can confirm this method in fact works well. I didnt have to cut the heater core cover though, it came out in one piece and went back in just fine. I didnt need to add a screw to the radio stabilizing plastic as i have an aftermarket radio and it doesnt even touch it. Id do it again, wasnt really hard. Took me about 5 hours. Good call on the pan under the car, lost about a half gallon of fluid.
 

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Hey everybody, new member here.
I originally joined up to be able to see the pics on how to replace the heater core on my sons 2002 Trailblazer. And after starting the procedure, I thought that with a few modifications,
it should be possible to R&R the heater core without dash, vent system removal, and A/C system discharge and recharging...

And it can indeed be done.
And this is how I did it.

First, all that has to be removed is the instrument cluster/radio trim bezel, the radio and ventilation control panel, the dash center support bracket, center console, the heater core lower cover, and the floor vent ducts.
Now of course to remove the trim bezel, the panel below the steering column has to be removed to get to some of the bezel retaining screws.

Once these parts are out, some of the dash fiberglass material behind the radio/vent control panel has to be cut out in order to be able to remove the dash/ventbox support bracket.
Part of what gets cut out has to reinstalled in order to support the back of the radio.
This pic shows part of what was cut out, and kept for the rear radio support.
More below this piece was also cut out.
Just be sure you don't cut through any wiring...
You will also notice I added a second 7mm screw to the radio support piece, just to strengthen it up a bit.

Hi I’ve got a 2002 Envoy with same issues...but I can’t see the pictures
 

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2004 chevy trailblazer_ls_ext
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Hi I’ve got a 2002 Envoy with same issues...but I can’t see the pictures
That's because when P-bucket launched their $400 dollar/per year photo hosting extortion scheme, those who didn't pay up lost the links to any photos they had embedded in any posts on the web. Sorry, but unless the OP redoes this post, they're gone for good. And since he hasn't been back in over 6 years, I don't think he's coming back.
 

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Here you can see two of the 5.5mm screws that hold the heater core lower cover on.
There is a third screw that can be accessed through this opening, just to the left.
There are 13 total screws, IIRC.
There was also a 10mm nut and stud that attached the lower heater core cover to the support bracket. This was unnecessary IMO, so I cut it off of the cover, once removed...

You can also see that wiring harness retainer also has two clips that attach to the support bracket.
I chose to cut them off. The harness isn't going anywhere with, or without them...
Hello anyone out there, why can’t i see the pictures? Can’t find any video in youtube about it. I need replace my heater core on 2007 trailblazer. I need very much see how do the job as was done this easy way
 

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2004 GMC Envoy SLT 4.2
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Hello anyone out there, why can’t i see the pictures? Can’t find any video in youtube about it. I need replace my heater core on 2007 trailblazer. I need very much see how do the job as was done this easy way
That's because when P-bucket launched their $400 dollar/per year photo hosting extortion scheme, those who didn't pay up lost the links to any photos they had embedded in any posts on the web. Sorry, but unless the OP redoes this post, they're gone for good. And since he hasn't been back in over 6 years, I don't think he's coming back.
 

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I will try do this task, that for me sounds insanity, so pissed at these so so-called Engeneers. Some cara are so simple just slidding out the heater core by the floor or glove box. Well iam here trying picture in my mind the description of the job done before by our fellows. I ll take pictures in the process or even record video and maybe throw on youtube. Will update when get this done.
 
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