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Rotate dash, replace defrost door, hvac flow distribution flap box

konstan

Diesel junkie
Messages
85
Likes
4
Location
Omaha, NE
Thread starter #1
When I bought this truck, the a/c itself was cold enough but the air was mainly blowing out of the defroster vents, onto the windshield.

Everyone will first tell you to check the actuator motor, and you should. There are two plastic linkage arms that are flimsy and need to be set back into place once in a while.

This HOWTO is the next step, if the linkage isn't the (only) problem. There is a box with a couple of flaps that sometimes melts. The flaps themselves melt (you'll see it in the pics) and the holes where the flaps pivot get deformed. The box you are looking for is GM Part# 52467204..

This was a day-and-a-half job for me but I was taking pictures, breaks to go get parts, and I generally am slow.
 
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deejaaa

Diesel Beginner
Messages
1,657
Likes
465
Location
Texas
#2
should be good, can't wait........
When I bought this truck, the a/c itself was cold enough but the air was mainly blowing out of the defroster vents, onto the windshield.

Everyone will first tell you to check the actuator motor, and you should. There are two plastic linkage arms that are flimsy and need to be set back into place once in a while.

This HOWTO is the next step, if the linkage isn't the (only) problem. There is a box with a couple of flaps that sometimes melts. The flaps themselves melt (you'll see it in the pics) and the holes where the flaps pivot get deformed.

This was a day-and-a-half job for me but I was taking pictures, breaks to go get parts, and I generally am slow.
 

konstan

Diesel junkie
Messages
85
Likes
4
Location
Omaha, NE
Thread starter #3
Here is the step by step with pictures.

Step 0. This is serious business :D. Get yourself some plastic trays (harbor freight sells them) for sorting and labeling all the screws, or do what I did and use the small clear plastic sandwich bags. Makes the assembly go _a_lot_ easier:



Step 1. Initial preparation. Disconnect the "-" battery terminals on both batteries. Remove the Air Bag Fuse (#10, 10 AMP). Then remove the center console and the driver's seat. These are fairly easy so I did not bother photographing this step. The two rear nuts that hold the console to the floor are a pain but you can get 'em with a wrench, it just takes forever.

Step 2. Remove the dash bezel. Disconnect the headlight switch, the cargo light switch and the 4x4 switch if equipped. Remove the knee panel in front of the driver's seat. There are three screws along the bottom of this panel that are holding it in place, and several more metal snap things along its top, just gently pry them out.

Step 3. Remove metal plate #1 under the steering column:



Remove metal plate #2:

 
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konstan

Diesel junkie
Messages
85
Likes
4
Location
Omaha, NE
Thread starter #4
Step 4. Remove all steering column nuts. There are 4 of them, in two pairs.

Upper (further away from the firewall):



Lower (closer to the firewall):



Step 5. Finish removing the steering column. Remove the air bag fuse (this should probably have been done way earlier).
Disconnect the yellow air bag wire (it is labeled in big letters, you won't miss it)



Step 6. Remove the bolt that holds the steering column wiring harness to its plug. When you unbolt the bolt, the harness should come out easily. Sorry about the crappy picture on this one:



Step 7. Remove the cross bolt at the base of the steering column. Its just one bolt. and for some reason I can't find the picture of it that I am pretty sure I took.

Step 8. My truck has auto transmission, so I also had to disconnect the transmission shifter linkage. There are two parts that need to be disconnected:

This cable needs to come out of its holder:



This ball linkage needs to be unsnapped (carefully with a flat blade screwdriver):



Linkage taken apart:




The steering column should come out now. Pull it out gently, it does not take any force at all, and it will come out:

 

konstan

Diesel junkie
Messages
85
Likes
4
Location
Omaha, NE
Thread starter #5
Step 9. Let's get the dash out of the way now.

Dash rattle stop screws. There are three of those screws. They are right in the middle of the defroster vent. You can't possibly miss them. Take out all three. NOTE: "Walking J Designs" sells special tabs that go between these screws and the dash, to prevent rattle, cracking, etc, and I recommend that you use them.




Step 10. Dash pivot bolts. they prevent the dash from rotating. There are two of them, one on the driver side and one on the passenger side:



I also had to take this lone screw out. It holds the dash to some kind of a mounting bracket with some sort of an electronic device on it:



The dash will rotate towards you and down now:

 

konstan

Diesel junkie
Messages
85
Likes
4
Location
Omaha, NE
Thread starter #6
Step 11. You can now get to the hvac box and replace the infamous part 52467204 with the two doors in it. I was able to see the problem right away. My defrost door fell out of the pivot hole, its rubber outer gasket is all melted, not a pretty sight:





The door does not come by itself as a part, you have to buy the valve box that has two of the doors in it. $69 bucks and as far as I know, its a dealership part only. So, your next step is

Step 12. Obtain the replacement door from the boneyard or the valve box from the stealership:

 

konstan

Diesel junkie
Messages
85
Likes
4
Location
Omaha, NE
Thread starter #7
Step 13. Taking the valve box out is somewhat nontrivial. There are four metal clips that hold it in place, plus its flange is fitted inside the rest of the hvac box. This pic actually shows my new valve box in place, but you get the idea:



The two clips in the front are easy. The left rear one is hard to get to. The right rear one is a bear. After you take the first three clips off, carefully pry the rear part of the box toward you so you can stick a flat blade screwdriver in there and get rid of that clip. No, you won't be reinstalling the fourth clip. I dont see how, without completely removing the entire hvac box.

Before you put the new valve box in, I recommend a slight modification which will make it easier (possible?) to install it. Your new box has a round flange that should fit into the hvac box. The fit is tight, so what I did is trimmed part of that flange:



I am not saying that this is what *must* do, far be it from me to say that you must maul a $70 part in such an unseemly fashion... but this helped avoid a whole lot of extra disassembly.
 

konstan

Diesel junkie
Messages
85
Likes
4
Location
Omaha, NE
Thread starter #8
Step 14. Here is where the new box goes:



Install the valve box. Starting with the side closest to you, then the rear part of the flange will snap into place. Use the three metal clips to affix the valve box in place. I am sure three clips are sufficient, and besides, I could not see a way to get the fourth clip on. and transfer the foamy seal from the old valve box on to the new one.

Here it is, installed:

 

konstan

Diesel junkie
Messages
85
Likes
4
Location
Omaha, NE
Thread starter #9
Step 15. Put everything back together:

Rotate the dash into place and bolt in.
Reinstall the steering column and metal plates.
Reinstall the knee panel.
Reinstall the dash bezel.
Reinstall the seat and the center console.

A few notes on reassembly:

- When rotating the dash into place, keep track of where your auto transmission shift cable is (if truck equipped with auto transmission). Make sure it does not get jammed because if it does you have to unbolt the dash again.

- Do not forget to connect the hvac hose that goes to the vent that points below your waist, right under the steering wheel.

- "The dash rattle stop bolts" hold a significant load. When installed, they pull the dash about another inch towards the windshield. When tightening them, please gently push the dash up and forward, then tighten these bolts. DO NOT RELY on the bolts themselves to just pull the dash up. They might, or you may crack the dash where these bolts go though it.
*** if you can afford it, spend the $15 bucks and get the aftermarket replacements from Walking J ***

- Steering column needs to be completely bolted into place before attempting to start truck. Well, some of you may think that's obvious.

- Use loctite on the dash pivot bolts and steering column bolts.
 

deejaaa

Diesel Beginner
Messages
1,657
Likes
465
Location
Texas
#10
think i might need this also. i can feel air at the feet while driving. i don't have a/c now but don't want to have outside air coming in when i do fix it.

GREAT write up BTW!
 

tanman_2006

Just a farm kid...
Messages
5,505
Likes
516
Location
Seiling, Oklahoma
#13
I might use this soon. My ac gets cold, blower runs good, but the air does not come out of the vents.

On another truck the Air is stuck on floor and defrost...

You made the job look easy!
 

DieselCash

Trust but, verify
Staff member
Moderator
Messages
6,443
Likes
204
Location
Salado, Texas
Staff #14
I might use this soon. My ac gets cold, blower runs good, but the air does not come out of the vents.

On another truck the Air is stuck on floor and defrost...

You made the job look easy!
It is not that difficult just very time consuming.

I hole hardily agree with the above and label everything you remove. It will make life 100% easier when it comes time to put everything back together.

Take lots of pictures, when it come to multilayer task like this it is worth way more than 1,000 words.
 

Judge77

New Member
Messages
3
Likes
3
Location
Vegas
#15
I'm fixing this same problem. I have purchased the doors, but cannot seem to separate the small pot metal arm on the left side of the picture above from the arm of the old door. I need to do this to transfer the arm to the new door as well as install the new door into the valve box assembly. I've searched off and on across the internet for weeks on this topic and this is the only place I see the two pieces successfully separated. I'm hoping the OP might be able to shed some light on how he did it.

This is for a 1995 GMC Suburban K1500 6.5L Turbo Diesel. Thanks in advance for anyone that might be able to help.
 

SmithvilleD

Active Member
Messages
910
Likes
123
Location
St Joseph, MO
#16
I'm not the original poster, but did this job a few months back. If memory serves, I got a small, thin Cresent wrench on the shaft, squeezed in btwn the plastic housing & the pot metal arm's shoulders. Then sprayed down the arm/shaft with Knock-Er Loose penetrant. Gave the shaft several sharp taps via small hammer & pin punch.

Needed the cresent wrench or something backing the lever arm, to better direct the force of the taps to separate the shaft & arm. It's not really a strong interference fit. Just grows together a bit over the years.
 
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