Pulling Dash - Anything I'm Missing?

[fl0w3n]

I plan to eventually pull my full dash apart to fix a few things that have been getting on my nerves. Since it's a pretty big task and I don't want to do it more than once, I just want to double check if there's anything I might be missing that I should look at while I'm there. It's going to be a decent chunk of money but I'm hoping it pays off in lasting comfort for the next 150k miles.

Here's what I'm thinking -
- All 4 blend doors, or at least the 2-3 that can't be reached with the dash in place (currently having interment issues with passenger side sticking, after I fixed driver side. Plus obnoxious hunting noises)
-Fan motor - on fan speed 1 I get a subtle but obnoxious chirping sound
-Dynamat underside of dash pad - I'm getting a rattle above the gauge cluster that is subtle but again, gets on my nerves

That's it for things actually wrong right now, but in addition to that I am considering replacing the heater core now as preventative maintenance while I'm there. I'm also considering dynamatting the backside of the firewall. Eventually I'd like to get the rest of the cab, but again, trying to only pull the dash once.

So, are there any components back there I'm forgetting about that might be worth replacing when I'm there? Anything on the column? Anything else HVAC related?

Also, I know dynamat is pretty dang adhesive, but has anyone ever tried sticking it on the dash plastic? For my dash rattles, I'm hoping that if the extra weight of the material doesn't stop the rattle itself, then at least the sound will be deadened.

 

[Chevy1925]

how deep you wanna get? i would say a new shift cable, clean the evap thoroughly, grease the column and look for worn parts, look for puckered plastic ducting at junctions that might be loosing air and tape up, fix any degrading foam that seals duct joints. that probably be about it that i can quickly think of

 

[fl0w3n]

how deep you wanna get? i would say a new shift cable, clean the evap thoroughly, grease the column and look for worn parts, look for puckered plastic ducting at junctions that might be loosing air and tape up, fix any degrading foam that seals duct joints. that probably be about it that i can quickly think of

If it's a commonly reported issue, I'll go deeeep haha.

Looks like the shift cable is $100? Do they stretch out or just break? My cluster looks like it was already repaired by the PO so that should be good.

Good points on everything else, a little elbow grease and consumables should go a long way. Any suggestion on the foam for the duct joints? Is it ghetto to use the metallic HVAC tape, or even duct tape? I don't want to ghetto rig things but I know that foam is a brittle and obnoxious.

 

[Chevy1925]

i dont know where they get the foam but it looks identical to the foam strips you can buy at RV trailer stores for sealing doors. i dont see why that wouldnt work in place.

id use the hvac tape if it stands up over time. i dont think duct tape does well.

yeah the cables over time get stiff and then snap. there is also the spring and detent that the shifter uses on the column. check the spring to make sure it aint broke or coming apart. ive seen those go a few times.

 

[Bdsankey]

I'm in the same boat this winter while the motor gets finished up. I'm going to be doing all blend door actuators/checking doors for cracks/sealing them, applying HVAC tape at every seam, resealing ducts, new heater core, new A/C evap core, and sound deadening the firewall/front seats forward. Like you, it's a giant pain in the rear to do the job so I'd rather just knock it all out. My truck has 270k and the HVAC system is awful.

The evap core loves to freeze over, the vents don't go where you want them, sometimes its hot when you want cold and sometimes its warm when you want hot etc.

 

[Hoser]

Doing the heater core as preventive maintenance is another big step in the dash disassembly process. I personally would be inclined to just flush it and inspect it to make sure it’s not leaking. pretty common for trucks with well over 300k on them and original heater core is still great and not leaking.

Which truck I your signature are you doing this on? If it’s the ‘04 I suggest cutting the bottom of the airbox where the ‘01 & ‘02 trucks have the cabin air filters. Even if you don’t add the filters, which I suggest doing, it will give you access to the evap core to clean it like James suggested. Them things can get real nasty and will lead to poor airflow and the freezing up issue mentioned. Having that hole will allow you to get a hose in there and spray that evap core real good. I’m sure you know you can buy the cabin filter kit, but it’s easy to just make your own with some scrap plastic or metal and foam. When you pull the giant duct out that goes across the entire dash, it’s a good idea to scrub out the inside, they can get nasty, but I’m sure you were planning on doing that already.

if you plan on adding a stereo with a microphone, it would be a good time to run the wire from the back side of the radio to the a-pillar, or any other wires for that matter.

about all I can think of for now.

 

[Leadfoot]

Good luck with the project. I remember doing the dash in an old 80's Mercury Marquis to replace a leaking heater core and fix some vent doors (after driving home Ace Ventura style in the dead of winter) and it was a process with a million screws and parts. Had the entire dash in the back seat and column on the floor (was in a tiny garage which was the only place I had with heat to work while in college). I had a buddy at an old dealership that printed me out the booklet of instructions which helped a ton. That said, is there instructions/tutorial on dash removal for these trucks anywhere online if we are ever in need?

 

[fl0w3n]

It’s the 04 I plan on doing it to, and another good point on adding the filter.

I guess I can inspect the heater core and just clean it out, I’d just hate to take it all apart and see that it is indeed bad and then be sitting around waiting for a replacement.

@Bdsankey which blend doors were you planning on using? I’m planning on the AC Delcos from Rockauto, but the GM parts tech I bought one from a few months ago warned me that the “online ones aren’t reliable”. I doubt Rockauto is selling knockoff AC Delco...

 

[Bdsankey]

It’s the 04 I plan on doing it to, and another good point on adding the filter.

I guess I can inspect the heater core and just clean it out, I’d just hate to take it all apart and see that it is indeed bad and then be sitting around waiting for a replacement.

@Bdsankey which blend doors were you planning on using? I’m planning on the AC Delcos from Rockauto, but the GM parts tech I bought one from a few months ago warned me that the “online ones aren’t reliable”. I doubt Rockauto is selling knockoff AC Delco...

I’m planning on going to the dealer for all the actuators, heater core, and evap core.

 

[Dozerboy]

For sound deadening I wouldn’t use Dynomat. I have a sound deadening project I did on my truck that I posted about. While I didn’t do anything under the dash from the research I’ve done you should use foam or High density vinyl(?). My understanding is products like Dynomat with aluminum backing try and make floppy metal more rigid and cancel out some vibrations. I don’t really think that’s the issue with the firewall. You want some heavy mat like HDV or foam to insulate and absorb noises. There are guys that have gone as far as putting foam inside the ductwork and wrapping all the plastic behind the dash in foam to stop rattles/movement and wind noise from the HVAC.

 

[fl0w3n]

I’m planning on going to the dealer for all the actuators, heater core, and evap core.

Dang, I assume you're getting it at a discount because of your shop? I wound up getting one blend door actuator from the dealer and it was hundreds of dollars for an AC Delco one, I want to say something like $340. Rockauto has AC Delco for less than $100. Hard to swallow, but I do like using factory parts unless there is a legitimate tried and true upgrade.

For sound deadening I wouldn’t use Dynomat. I have a sound deadening project I did on my truck that I posted about. While I didn’t do anything under the dash from the research I’ve done you should use foam or High density vinyl(?). My understanding is products like Dynomat with aluminum backing try and make floppy metal more rigid and cancel out some vibrations. I don’t really think that’s the issue with the firewall. You want some heavy mat like HDV or foam to insulate and absorb noises. There are guys that have gone as far as putting foam inside the ductwork and wrapping all the plastic behind the dash in foam to stop rattles/movement and wind noise from the HVAC.

Interesting, I'll have to look into that. Makes sense on cancelling movement on something like a curved door panel skin, whereas the firewall is rigid and like you're saying just additional blocking is what I'm after.

I'll see what I can find on the old google machine

 

[fl0w3n]

Well, this whole project just got even more involved.

I just picked up fully loaded seats (both power/heated/lumbar/memory) and a center console, plus the door panels.

so looks like I’ll have the entire cab gutted, because at that point I might as well pull the carpet and pressure wash it out.

then it’ll be a project adapting the passenger seat to have proper controls, and getting the center console to fit. I’d like if the rear air can work, but not a huge deal if it doesn’t. Just to make it even more complicated, I’ll be swapping the leather seats I just got to cloth.

 

[fl0w3n]

Okay I got lucky and the guy who was selling the seats cut them out on the body side of the harness, so I at least have the connector to go into the passenger seat.

I am looking at C399, but what's weird to me is it doesn't fully match what All Data is telling me. Is this common because of variance in options or am I just looking at the wrong thing?

From the perspective of my connector (I know it's reversed in my picture, but you can't tell wire color from head on)
A-D matches
E-F doesn't match
G-H matches, but why is there two H's?
J-L doesn't match and doesn't make sense

When looking at the connector call out, going from J-S doesn't even make sense, why skip N and O on the connector lettering?

I see Ground #304 under the seat, but I don't see a ground pin in C399, so how is the seat grounded?

 

[fl0w3n]

I'm also confused because I can't find connector details about where C399 goes to. Is it going straight to the BCM like I highlighted? Edit: I think I answered my own question, it's not going straight to BCM because I don't see anything about it in the BCM.