[Sam Axe]

Looking at the heater box doors, it appears that at some point there was some sort of adhesive on one side. This would suggest that there was perhaps a seal glued to the doors.

The door that decides if you're getting Heater Core or Evaporator has a rubbish seal, but in both of my boxes the other doors don't. Was there ever one there? Did they disintegrate over the years?

Specifically, the door on the right hand side of the picture has what appears to be glue reside on the other side, but there's no evidence or remains of, well, anything? Same with the small metal door that directs air between defrost and floor. It has staples shot through it, but they aren't holding anything, and there's no remains IF there was anything there at all.

So what, if anything should be here? I'm considering making felt seals. At least the doors won't "clunk" when they open and close.

 

[BA.]

I have no idea man but I seem to recall that same residue on mine that you are mentioning. I can't recall if I did the thing felt strip idea like you mentioned but that does sound kind of familiar as well.

 

[richard.gerig]

There is supposed to be a sealing material on those flapper pieces.mine is the same way. I'm experimenting with some material to glue back on

 

[Sam Axe]

Been playing around with felt, but I’m thinking a sheet would work better than trying to make a casket.

 

[Sam Axe]

Made some progress. Since internal baffles aren't available and used ones are cracked, warped, or both, I had one scanned and 3D printed. The baffle doors are pressed onto a D shaped shaft to prevent them from rotating, and they're somewhat difficult to remove. So I had the baffle printed in two parts, with a parting line on the center of the shaft. This way, I could cut the old baffle out and install the new one without removing the doors.

3D printing has it's drawbacks. Resin printers have very high resolution and the parts come out fully finished, but the only available material is resin. Filament printers have a wider variety of materials, but the resolution isn't all that great. My parts are filament printed. With the low resolution, there is a very real chance that airflow could result in whistling. To prevent this, I applied a layer of 3M glazing putty over all surfaces where the airflow is perpendicular to the printer grain, and finished them off with 220. I hope this works...

For the door seals, I used 1/8 inch felt sourced from McMaster Carr. 1 sq ft is plenty for the entire heater box. For the door that directs air to either the heat of AC vents, the felt was cut to 7.5 x 4.5 inches. 1/8 inch appears to fit very well, and dampens the sound of the door opening and closing.

The AC/Heat vent director door with felt in place:

Lower half of baffle installed and linkage adjusted:

 

[65_&_67_Impala]

I've often wondered if it was possible to get some stuff scanned in order to print a new piece. otherwise, having to do all the measurements would really suck

 

[Sam Axe]

All the felt is in place. Not sure if it's necessary, but it certainly muffles the doors when opening and closing.
I've assembled and test fit these parts countless times making sure everything fits properly, operates smoothly, and doesn't interfere with other part.

In this installment, I assembled the door that directs air between the floor or defrost. The door had three staples in it, two from the top on the left, and one from the bottom on the right. This led me to believe that it originally had tow separate pieces attached to it. I cut my pieces 2 7/8 inch wide. This is a little wide, but it gives extra material to trim for smooth operation. For length, one piece is 2 1/8, and the second is 5 1/2. Both are attached using 3M spray on interior trim adhesive.

Smaller piece in place. This side closes off the floor vent.

Larger piece. This side closes off the defrost vent. I cut a notch in the felt where a screw comes in through the side.

1/8 inch felt does a very nice job of closing off the defrost vent

I used a scale to demonstrate how the floor vent closes off. This piece a little long so it hangs over the end. It worked out pretty good.

I addition to several screws, there's 3 rivets that hold this part together. Rather than rivets, I chose to drill out the holes and use #6 button head screws with fiber lock nuts.

 

[BA.]

Great work man. I can't imagine how many hours you have in that heater box situation by now. ...Whew!!

 

[MistBlue65]

I agree, great work! I will definitely be consulting this thread when I tear mine apart, although I'm dreading doing so.

 

[Sam Axe]

Thanks for the generous comments guys, and Mist, I'd like to see some pictures of your car brother.

Don't give the HVAC overhaul a second thought. Take lots of pictures during dissassembly, and I mean every screw from every angle. Once you start working on it you'll quickly understand how it all works. Also, and I can't stress this enough, test fit everything. Every time you add a part, test everything for smooth, nearly effortless motion.

So I made a little progress. I was planning to use a stock replacement copper hearer core, but the one from OER fit so poorly and cost so much that I didn't want to risk trying to make it fit. This got me to thinking, and it went something like this...

Since the car has a modern engine,...
and modern engines use the orange coolant...
and modern coolant is friendly to aluminum heater cores...
and since modern aluminum heater cores deliver hot air faster...
Why not use an aluminum heater core?

Got one from Rock Auto and it not only fit very well, it's made so the core itself is never in contact with the core support. I really like this feature. Another good point is that the core support is aluminum as well, diminishing the possibility of dissimilar metal corrosion.

Specifics on the heater core are:
APDI PRO
Part Number: 9010062
Cost: $57.79

The only issue was the steel straps that hold the stock core in place could be a source for dissimilar metal corrosion, but they really don't fit the core very well at all.

In order to get rid of the metal, AND find something that would hold the core securely, I decided to try zip ties.

I found where the core was happy in the heater box with the core support in place and marked the inside of the core in order to duplicate the location on the bench. Once lined up, I marked the placement for new holes for the zip ties. It worked perfectly. There's absolutely no slop in the core and it fits just like it should.

Here's a couple pictures of the heater core all strapped in. The straps acted like the wanted to slip off the tanks. They didn't, but I didn't want to take any chances, so I used smaller zip ties to pull them back. They don't need to be tight, they just need to keep the straps from slipping off the tank.

Test fit number 833,972...

All sealed in with black RTV gasket sealer. I also sealed the original screw holes with RTV. You can just see one at the far end of the zip tie. All that's left is the bazillion detail parts. Did I mention to take a lot of pictures?

 

[MistBlue65]

Thanks for the advice, Sam! I also need to replace my heater core, so I'll steer clear of OER. Each part I buy from them makes me less and less impressed with their products.

Not to derail this thread, but here's a few pics of my rig, as requested. I was told by the p.o. that she spent most of her life in Arkansas before migrating up north in '96. Unlike Sam, my plan is to go back to showroom condition with a few modern upgrades like front disc brakes, 15" wheels, some aftermarket oil and temp gauges, and a Bluetooth input to the original radio (I know, I'm changing so many things!) She currently runs, drives, and stops, and floor pans are up next before I try to get her on the road this Summer. Long road ahead, but definitely a fun one so far. I'll definitely be following this thread cause I'll need all the help I can get when I tear into my box.

-Sam

 

[Sam Axe]

I have a thread on doing a C3 corvette brake swap. The front is a direct swap. Also had my original radio updated with modern internals by Joe’s custom car radio. No thread on that tho. I would suggest getting your radio sent out ASAP because my wait time was about 9 months.

 

[MistBlue65]

I'm too much of a "purist" to update an original radio with new electronics (I got started on antique radios before classic cars), so I did the work myself. I got the old radio working and then added a cheap Bluetooth board off Amazon to it. Uses the original circuitry and I can now play whatever I want. If there's any interest, I'll make a separate thread detailing what I did.

Best,
Sam

 

[Sam Axe]

Back to the HVAC. There's a vacuum valve on top of the heater box that is activated by the temperature control lever. When moved all the way over to cold, it either applies or cuts vacuum to the Suction Throttle Valve (STV). I haven't read up on this yet, but from what I understand so far, the AC compressor runs whenever the AC is on, and the STV controls the flow of freon (used generically because I can't remember one "R" from another) out of the evaporator.

Old Air products offers a kit that changes the system over to a "Cycle Clutch" system. It uses a thermocouple to turn the compressor on/off as the AC system requires freon. This SHOULD help reduce fuel consumption.

For those purists (cough, Mist) there is no cosmetic changes other than the thermo/electric switch that wires into the AC Compressor circuit.

But that's not what this post is about...

This post is about vacuum lines and that little vacuum valve that sits on top of the heater box. I have two of which that need cleaned up and nursed back to health. At least that's what I thought.

It turns out that when you update the STV, this little vacuum valve, that sits on top of the heater box, no longer has a useful function.

In fact, if you install hydroboost, a modern electronic transmission, and update the STV, the only thing left that sucks is the Fresh/Inside air valve located in the right hand cowl.

So my vacuum schematic goes from this:

To this:

 

[MistBlue65]

Sam, thanks again for the invaluable info! I have to confess, me being a "purist" may or may not be financially motivated. If the Old Air kit is less thank a full stock setup, that may be the way I go. It's a long ways away, but it gives me something to think about.

-Sam

 

[Sam Axe]

Mist, I’m keeping the full stock HVAC system. The only change is the STV conversion. I think it’s possible to mount the cycle switch inside the evap housing in order to hide it. But it makes replacement difficult.

I’ll start a thread on evap housing overhaul soon because that’s next.

I looked at the aftermarket systems and none of them have an option for fresh air. This is why I’m going to all the trouble of rebuilding my stock HVAC.

 

[MistBlue65]

Oh ok, gotcha. I guess I was thinking non-stock meant the setup you described with the STV conversion, and not something completely aftermarket like Vintage Air. Good luck with the evap housing! I'll definitely be following along on that one.

 

[Sam Axe]

I considered both Vintage Air and Old Air Products conversions, and there’s a couple reasons I chose to overhaul.

Neither have the option for outside/inside air.
And
Both place their logo on the heater controls.

In my humble opinion, either one of those is a deal breaker. At least for me.

Old Air Products has in increasing selection of restoration parts, and they took time to answer all my dumb questions. Which reminds me, I have a couple more dumb questions…

 

[brickwhite]

Classic auto air has one too, it uses factory controls but no external Air, and it doesn't fit vents if car had AC before.

1966 Chevy Impala - Sedan Air Conditioning Kit | 66 Chevy Impala - Sedan AC

Need A/C To Cool Your Classic Ride? 1966 Chevy Impala - Sedan Air Conditioning Kit from Classic Auto Air. High Performance / High Efficiency 66 Chevy Impala - Sedan AC Kits.

www.classicautoair.com

I'll be probably buying the Vintage air because it incorporates Factory AC vent locations, and they have cable converter kit that allows for OE control usage.. not it in the impala kit but can be retro fitted, I think.

PN - 49767-LCE

Complete Kits - Vintage Air

www.vintageair.com

 

[Sam Axe]

Ted
I bought a new HVAC controller and it arrived with the vac valve damaged, so they sent me another one. I have a spare vac valve I can install on it if you’re interested.