CJ7 Heater Box and Fresh Air Duct Restoration (video/photos/video/foam templates) - JeepForum.com
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post #1 of 12 Old 04-25-2019, 07:16 PM Thread Starter
Ucandoit2
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CJ7 Heater Box and Fresh Air Duct Restoration (video/photos/video/foam templates)

In this thread, I am going to remove and restore the Heater Box and Fresh Air Duct from my 1979 CJ7. I want to start by thanking all of the contributors to the previously posted thread on this topic as it jumpstarted my research and really pointed me in the correct direction. That thread spanned over 8 years and the solutions changes with new contributors offering alternatives. I have collected all of those thought here and have executed what I thought were the best ideas.

The original thread can be reviewed here:
https://www.jeepforum.com/forum/f8/c...-heavy-975999/

That thread is about 8 years old and throughout the years many contributors continually provided great suggestions and new alternatives to the restoration of these units. I took many notes and pulled what I thought was the best options and applied them to my restoration.

UPGRADE INCLUDED DURING THIS RESTORATION
There are several items that will be fixed or upgrade during this process. Here is a short list of those items
• Heater Core Replacement
• Blower Motor Upgrade (Mod) – More CFM with upgraded motor
• Replace Foam padding on Air Diverter Gates – Improve control of airflow
• Seal Lower portion of Heater Box to prevent possible leaks into vehicle

PART LIST and DIAGRAMS of FOAM PIECES FOR THE GATES are located in a document that is attached to this thread. It can be downloaded for Free.

I recorded many of the options that others provided in a document and I highlighted the options that I took which will match the photos that I provide below. I also will include a link to video that wil walk you through the process that I took.
As mentioned later in this thread, I decided to create full size templates of the pads needed for the diverter gates as well as the large penetration gaskets that I used. This really helped in cutting out the replacement parts. The Parts List and Templates are available as a free downloadable 4 page PDF at the link above.

PROCESS
In my situation, I have just removed my dash as a part of the complete restoration project that I am currently working on. Removing the dash is not required to remove the Heater Box, and I cannot see any reason why the Fresh Air Duct would not also be easy to remove without removing the dash. This thread will include both items, but you could certainly use this information for just the Heater Box if that is your intent.


That’s enough of an introduction and I hope you decide to follow along. And hope that this helps someone update their ole Jeep.

Mike

Let’s dig in! I started by disconnecting anything that was attached to the units.

If you are just removing the Heater Box, you will need to disconnect the following items and then the
Heater box can be removed:
1. Temperature Mixing Gate Cable
2. Defrost Gate Cable
3. Passenger Vent Gate Cable (far right side)
4. Defrost flexible duct lower connection

If you are removing both the Heater Box and Fresh Air Duct, you will want to remove the Heater Box first, then also disconnect the following items:
5. Defrost vent (2 screws from the top)
6. Fresh Air Gate Cable
7. Blower Motor Resister electrical connection



Under the hood, I removed my Battery and Battery Tray. Here is a list of items that will need to be disconnected:
1. Heater Box Drain Hose (below the Blower Motor)
2. Blower Motor Electrical connection
3. 2 Heater Core Hoses (orange)
4. 4 Nuts (behind the air filter, above the heater core hoses, and two near the blower motor)
5. Fresh Air Duct Drain (only if you are removing the Fresh Air Duct)



Next, since I am remove the Fresh Air Duct, I needed to remove this grill. There are 6 screws holding on this grill and then 4 more screws underneath it. These are the only screws securing the Fresh Air Duct to the vehicle.


With those items disconnected, I was able to remove both the Heater Box and Fresh Air Duct from the vehicle.



With the assembly now on the bench, I needed to disconnect the Passenger Gate Cable, which I did not do while it was in the Jeep as I could take both parts out at the same time.


Here is a close-up of this connection. This is very typical of all cable connection on both units. There is a 3/16” Push Nut that can be removed with pliers or a screw driver, the spring just pulls off, and the cable stay snaps off with a screw driver. I needed to disconnect this so that I could separate the two units.



Attached Files
File Type: pdf Jeep CJ7 Heater Box Parts List and Diagrams.pdf (155.1 KB, 20 views)

UCanDoIt2

1979 Jeep CJ7 - GM 5.3L > AX15 > Dana300 Build CURRENT
Other Projects: 2000BMWE46, 2001BMWE38, 2007BMWE92, MercedesE350

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post #2 of 12 Old 04-25-2019, 07:18 PM Thread Starter
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Fresh Air Duct Restoration

Now that I have the two units separated, I wanted to start with restoring the Fresh Air Duct. Before taking things apart, I want to study how they all work. Here is a close-up of the Vent Gate open Close mechanism. With all of the linkages still connected, I moved it back and forth to check the operation. It would get a little stuck in the center position. There was some corrosion on the sliding parts that once cleaned up would prove to help the operation.


This is on the left side of the Fresh Air Duct and is the gate that allows fresh air to the driver’s side. On mine there was a problem with one of the edges catching on the side of the box. I ended up trimming of a 1/16” sliver of the rubber gasket to improve the performance. Here is a photo of the gate in its location and another of it after I took it out. The pivot rod on mine was quite rusty and was difficult to get off. I later learned that you can reach in and sand some of the exposed areas which made removal of other rods much easier.



This is the main fresh air gate area in the center of the unit. Take plenty of photos so that you can document the orientation and order of the pieces.


Here is a shot with all of the Gate parts laid out read to be reinstalled. All of the rods have been sanded and then polished with steel wool. The levers has been sanded and de-burred. The metal of the gates and any lever that doesn’t rub against another has been painted. The condition of the rubber gaskets on these two gates where fantastic. I elected to not replace these rubber seals as they appear to be ready for another 50 years.


Here is the Driver’s side reassembled. I tested it, and it works better now with the small sliver of rubber trimmed. It also still makes a perfect seal.


Here is the main section reassembled. The only type of fasteners that all of these gate assemblies use is a 3/16” push nut. If at any time you feel the push nut is not gripping as tight as it should, you can flatten it with a hammer and that will make it tighter.


This completes the work done on the Fresh Air Duct. Over all the entire assembly was cleaned, the rust was removed, some parts were painted, and the center assembly was tightened which now performs better.
On to the Heat Box!
Attached Files
File Type: pdf Jeep CJ7 Heater Box Parts List and Diagrams.pdf (155.1 KB, 15 views)

UCanDoIt2

1979 Jeep CJ7 - GM 5.3L > AX15 > Dana300 Build CURRENT
Other Projects: 2000BMWE46, 2001BMWE38, 2007BMWE92, MercedesE350

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post #3 of 12 Old 04-25-2019, 07:20 PM Thread Starter
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Heater Box Disassembly

As I mentioned earlier, there are several reason that you would want to service or restore your Heater Box:
- Replace your Heater Core
- Replace your Blower Motor (broken or not performing)
- Seal up the Box so that it does not leak inside the vehicle
- Replace and improve the Seal Gaskets on the Gates


This photo shows the backside of the unit. My left hand is pointing to the Heater Box Drain. It as well as all items that protrude through the fire wall have thick foam rubber gaskets on them to create a seal. My right hand is on the back of the blower motor and you can see that it also has a seal. In the bottom right of the photo, you can see one of the four mounting studs. It has a dense rubber “stand-off” isolator on it that will get replaced.


Replacing the thick gaskets… here is where people have become creative over the past 8 years. We are going to need to make some 1/4", 1/2", and 3/4" gaskets. As all of the gaskets measured to be a multiple of 1/4”, I elected to purchase this 1/4” thick Neoprene Sponge Foam. This roll was plenty to do the job and it cost me about $13 shipped to my door. This is 1/4 of the cost of some of the other solutions.


I summarize all of the parts and supplies as well as the diagrams that I used in this restoration in the document that is attached to this Thread.



Here is a photo of a pack of four Rubber Bumpers that I will use for the mounting stud stand-offs.



Now it’s time for the disassembly. I started by removing the Blower Motor. I inspected the Fan Blade and was happy to find that it is a very well made part. The plastic is very thick. It will be re-used, but the Blower Motor will be replaced. More about that later.



After removing all the screws and one push nut, the flat metal back plate was removed exposing the internals.



A lot of stuff has accumulated here over the past 40 years.



The first gate that I removed was the Temperature Mixing Gate. It has an internal control cable that is held on with a push nut. Other than that, the gate just pulls out. This gate is used to divert the flow of air either (1) to bypass the Heater Core, or (2) Pass through the Heater Core.




Next is the Defrost Gate removal. The control rod and lever are on the backside of this photo and are removed by pulling then out the back. Again rust on that rod makes it difficult to remove. Using a little sand paper on the exposed section of the rod will greatly help the removal process. The second photo shows an exploded view of this gate. I take a lot of pictures to help me during the assembly process.




Next, I removed the lower passenger fresh air duct to ease the access to its gate.



Here is have taken another photo of the order and layout of this gate.

Attached Files
File Type: pdf Jeep CJ7 Heater Box Parts List and Diagrams.pdf (155.1 KB, 18 views)

UCanDoIt2

1979 Jeep CJ7 - GM 5.3L > AX15 > Dana300 Build CURRENT
Other Projects: 2000BMWE46, 2001BMWE38, 2007BMWE92, MercedesE350

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post #4 of 12 Old 04-25-2019, 07:34 PM Thread Starter
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Heater Box Parts Replacement and Restoration

This first thing that I did was to sketch out the measurements of the Foam pieces that I was going to replace on the gates. Many of the foam pieces are mounted with a small offset and I wanted to make sure that I captured that prior to removing the old foam.



After reviewing my sketches, I determined that it would very easy to draw this foam pieces in MS Visio and then use those drawings as templates to cut them out of the new Foam material. Here is a shot of those drawings. You can download free these diagrams and the parts list as a single 4 page PDF document that is attached to this thread.



The back metal panel needed some attention. I sanded and painted it to help protect it.



All of the foam on the gates were replaced. They are all 1/4" thick. I used the diagrams to help cut them out and then used a Permatex Spray Adhesive (we used to call it spray trim adhesive). The diagrams also helped me with the required standoff placement of the new foam.

Here are a few photos of the Gates as they are being installed.





To help seal up especially the bottom of the Heater Box, I purchased this Butyl Tape. It is what is typically use on Campers to seal where the windows meet the metal siding. This tape is 1/2" by 1/16”. Since I have it, I decided to use it on the joint of the passenger duct.




The first Part replacement was the Heater Core. The old one serve me well for 40 years, but it was time to retire it. Here is its replacement. The old one was copper and the new one is Aluminum. There was a slight difference in the separation of the Inlet and exit tubes. I elected not to attempt to adjust them, but rather adjust the holes in the back metal plate. It was not far off and easily corrected. The Heater Core also received some of the Neoprene Foam as padding and as a gasket.



Next I applied the Butyl Tape to the perimeter of the Heater Box.



The next part that was replaced was the Blower Motor. You can purchase a direct replacement of the original part, but it doesn’t spin as fast as some other replacement options. I elected to upgrade to a Blower Motor from an early 70’s vehicle. The part number is PM102. The only physical difference is that the motor housing is 3.5” in diameter as opposed to the original 2 5/8. This means that the hole in the firewall will need to be enlarged to accommodate.



There are a couple of ways to enlarge the hole in the firewall. One would be to purchase a 3-1/2” Hole Saw and the other would be to use a Jigsaw. I elected to go the Jigsaw route since I already have one.

For both processes, it is going to be beneficial to establish the center of the existing hole. My approach to this was to (1) Mark the center of the circle on a piece of 1” thick wood. (2) Draw a circle that represents the existing 2-5/8” hole.



(3) Mount the Board on the engine side of the firewall. Using the 2-5/8” mark to align the board. Once this is done, the original circle center is “centered” on the hole. (4) Next, I marked the new 3-1/2” hole on the firewall. (5) Removed the Board then cut out the new hole with my jigsaw.



After a few test fits and some adjustments… It slide right in!



The last thing that needs to be addressed in the Gasket between the Fresh Air Duct and the Heater Box. I cut out an oversized piece of the Neoprene Foam and marked and cutout the shape of the bottom of the Fresh Air Duct.



Then I installed all of the Stud Stand-offs and other Gaskets so that I would get a true position of the heater box.



Then I marked the location of where to Trim and Glue the new gasket. After removing the Heater box one last time, I trimmed that gasket and glues it into place.



For my project, I am still working on my tub. The tub will eventually be removed from the frame so that I can get to the bottom side. With that said, I am not reinstalling these units at this time. The Reinstallation will be the reverse of the dis-assembly steps and by now you should be a pro!!!

Hope this helps you out! It has been a fun project.

Mike
YouTube: UCanDoIt2
Attached Files
File Type: pdf Jeep CJ7 Heater Box Parts List and Diagrams.pdf (155.1 KB, 10 views)
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1979 Jeep CJ7 - GM 5.3L > AX15 > Dana300 Build CURRENT
Other Projects: 2000BMWE46, 2001BMWE38, 2007BMWE92, MercedesE350

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post #5 of 12 Old 04-25-2019, 07:44 PM Thread Starter
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Heater Box and Fresh Air Duct Video

The above photos are a great way to visualize the steps that I took to restore the Heater Box and Fresh Air Duct in my Jeep CJ. During this process, I also video taped these steps. The below video also provide a step-by-step overview of what I did during the restoration. It also includes additional dialog.

Enjoy!!! Mike

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1979 Jeep CJ7 - GM 5.3L > AX15 > Dana300 Build CURRENT
Other Projects: 2000BMWE46, 2001BMWE38, 2007BMWE92, MercedesE350

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post #6 of 12 Old 04-25-2019, 07:51 PM
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You looked familiar in one of your pictures, then I noticed your Handle “UCanDoIt2”. I am one of your Subscribers on YouTube, and just watched “Drivetrain For Sale” last night. Awesome Channel, and I will be following along here. Thanks for sharing your knowledge and experience!


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MikeyDeezy Sez...Take ‘er E-Z and Keep it Breezy!
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post #7 of 12 Old 04-25-2019, 08:06 PM Thread Starter
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Small world and such a great community... this Jeep thing! I have owed my CJ7 for 31 years now! Cheers to you... Let's keep them rolling!!!!!

UCanDoIt2

1979 Jeep CJ7 - GM 5.3L > AX15 > Dana300 Build CURRENT
Other Projects: 2000BMWE46, 2001BMWE38, 2007BMWE92, MercedesE350

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post #8 of 12 Old 04-26-2019, 04:13 AM
John Strenk
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Nice work.
It appears you didn't have any problems with rusty parts. Did you soak everything down with PB-Blaster first ?
I snapped two bolts off my heater box but I just replaced them with regular bolts.


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post #9 of 12 Old 04-26-2019, 04:17 PM Thread Starter
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Quote:
Originally Posted by John Strenk View Post
Nice work.
It appears you didn't have any problems with rusty parts. Did you soak everything down with PB-Blaster first ?
I snapped two bolts off my heater box but I just replaced them with regular bolts.
I assume you are talking about the 4 Nut/Studs that hold the Heater Box to the Firewall. I did not soak them, mine came off fine. But that would be a great preventative measure.
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post #10 of 12 Old 04-26-2019, 06:18 PM
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Quote:
Originally Posted by John Strenk View Post
Nice work.
It appears you didn't have any problems with rusty parts. Did you soak everything down with PB-Blaster first ?
I snapped two bolts off my heater box but I just replaced them with regular bolts.
Hey John,

Everybody doesn't soak their Jeeps in road salt

JS
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post #11 of 12 Old 04-26-2019, 08:41 PM
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Extremely well done write up on the heater box. The pictures were fantastic as well!

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81/76 CJ5 304-t150-Spicer 20
82 Wagoneer 360-727-NP208
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post #12 of 12 Old 04-28-2019, 01:06 PM
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THANKS SO MUCH for taking the time to post this!!!!

Too bad stupidity isn't painful.
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