1967 Coupe with A/C Heater Core replacement

[Rocco S.]

After much research and planning I have finally decided to attack a leaking heater core in my 1967 L79 Coupe with A/C. It is an un-restored survivor car which has never been apart. I had to replace the original radiator last year with a Dewitts and knew in time the heater core would need attention. This last summer it started leaking in the interior, dripping on the floor mat and sending antifreeze laden mist up thru the defroster duct.

As you can imagine this is a major job on a car with A/C. The factory Service Manual and Assembly Manual are only partially helpful. But after following the procedure and finding it incomplete and with a real lack of details, I am at a standstill. The ductwork, console and console side panels were removed without issue. Even the radio and clock were removed (for service) easily. Next came the heater hoses at the firewall along with the 3 speed nuts. The inside control cables, vacuum hoses and wiring were removed next. The service manual mentions to remove the last remaining nut holding the heater box from the inside- far right corner. No problems.

That's when the job got difficult. A small diagram in the assembly manual revealed another hex nut on the inside, upper left behind the instrument cluster. Now the heater box is somewhat loose but cannot be pulled away from the firewall. It is loose enough that I don't feel there is any other fastener holding it in place.

The only thing is if the old sealer is holding it but I do not want to pull too hard or pry on the composite heater box for fear it could crack. The bottom of the box is much looser than the top and can be pulled away from the firewall about 1/2". The top moves only 1/8"-1/4".

Now for the questions.

1. Could it just be the 50+ year old sealer holding it in place?
2. Could I have missed a fastener?
3. Any other suggestions?

Thanks for any and all responses.
Frustrated,
Rocco

[Mike B.]

Re: 1967 Coupe with A/C Heater Core replacement

Hi Rocco,

I'm posting some NCRS TDB file shots I have of the firewall side of the AC Heater and Distributor Box (AIM C60/A2) from a '66 and '67. Mine's up in a box in the garage and these shots here are exactly what mine looked like when I removed it.

These photos should help visualize what's on "the other side".

Mike

[Greg H.]

Re: 1967 Coupe with A/C Heater Core replacement

Hi Rocco,
This is a major effort and I have removed my total AC assembly. I have the attached photos that I hope will help you. I have yet to attempt the re-assembly/ This is a 67 small block.

Good Luck and Merry Christmas!

[Peter M.]

Re: 1967 Coupe with A/C Heater Core replacement

Hi Rocco,
I think you are correct, it is likely the firewall gasket stuck. It is a terrible job, some butcher had replaced mine years ago. Did you remove the plate on the engine side? Kind regards and Merry Christmas.

[Rocco S.]

Re: 1967 Coupe with A/C Heater Core replacement

All,
Thanks for the posted photos and other responses. They were all helpful. Yes, I have removed the nuts holding the outer cover plate. It cannot be removed totally due to an A/C line and the heater core pipes.
It appears that all fasteners holding the box in place have been removed based on the posted photos. I will be making a tool to reach behind the box to separate the sealant from the inner firewall. I will report back when the box is removed.

[Page C.]

Re: 1967 Coupe with A/C Heater Core replacement

All will agree that this is NOT a fun job. The one fastener that is most overlooked is shown in Mike Browning first photo. This a metal bracket that is shown in the first photo in the top left corner. It is located between the round and oval opening in the heater box. It fastens to a stud that on the firewall with a nut. The bracket is attached to the plastic heater box with 2 screws. If the nut is not removed, there is a good chance of breaking the plastic part of the box where the 2 screws secure the bracket to the box.

[Jim T.]

Re: 1967 Coupe with A/C Heater Core replacement

I removed the heater core for my 1970 Corvette with factory air conditioning from inside the car. Did not remove anything from under the hood except the heater hoses from the heater core. This is the way the factory service manual reads to do it. How does the 1967 factory service manual say to do it?

[James W.]

Re: 1967 Coupe with A/C Heater Core replacement

I removed the heater core for my 1970 Corvette with factory air conditioning from inside the car. Did not remove anything from under the hood except the heater hoses from the heater core. This is the way the factory service manual reads to do it. How does the 1967 factory service manual say to do it?

I replace the heater core in my 1965 Corvette with a/c and did the entire job from the inside as directed by the service manual. The only thing I worked on in the engine compartment was the heater hoses and replaced the heater control valve. I will try and find my pictures and post them.

Regards and Happy New Year.

James West

[Rocco S.]

Re: 1967 Coupe with A/C Heater Core replacement

All,
Thanks again to all who responded. Due to the holidays, work has been suspended. I hope to get back to the heater box removal this week. In the meantime I have fabricated a tool that I think will help in breaking loose the heater box from the firewall. I have confirmed all fasteners have been removed and I an convinced the the gasket is preventing removal. I will report back on my efforts
.

[Robert W.]

Re: 1967 Coupe with A/C Heater Core replacement

I'm doing this now on my '66. Pulled outside box last weekend and the single nut located in the interior, on right side firewall just behind the RH vent grill near the carpet line was the hardest to get to. It's difficult to access, so I pulled the vent grill out of the way. No extreme measures should be needed to separate the halves after the nuts are all off, just some gentle persuasion.

[James W.]

Re: 1967 Coupe with A/C Heater Core replacement

Pictures of my '65 a/c after removal.


James

[Rocco S.]

Re: 1967 Coupe with A/C Heater Core replacement

Thanks to everyone who responded as it was very helpful. This morning I was successful in removing the entire heater box. Once I confirmed all the fasteners were removed it still took some effort and ingenuity to complete the removal, It seems that the gasket at the inner firewall as well as old sealant was preventing removal. Once I got the home-made tool behind the gasket I was able to break the seal.

After removal I inspected the gasket and noticed a small area was really compressed. Looking at the firewall from inside I saw what I believe to be an assembly line repair to the edge of the firewall opening. A small triangular piece was broken and was re-glued, It is not only poorly aligned but when re-glued it created a high spot. See the attached photo.

Even before the core was removed from the box there was a nice pool of coolant in the bottom of the box. After removing the core it was definitely leaking. See the photos including the date code confirming its the original core "67 C". My car was assembled on March 30, 1967. Now it's on to the radiator shop for a re-core.

[Harry S.]

Re: 1967 Coupe with A/C Heater Core replacement

Rocco, I just had two re-cored. The price in New Hampshire was $200.00. Just to give you a ball park number.

[Mike B.]

Re: 1967 Coupe with A/C Heater Core replacement

Hi Rocco,

Great photos of your heater core. I still need to have my original re-cored. I'll be watching this thread with your progress.

I've been doing research on various air conditioning fasteners on my '66. I spotted a screw in one of your photos just now that I'm interested in. It's one of the 4 screws that hold the evaporator in place. I'm attaching a copy of your photo and 4 of my evaporator mount screw.

Would you please post a closeup shot of your screw that I've highlighted by the arrow? I'm especially interested in the head mark(s) that your '67 has vs. my '66. Thanks Rocco

[Patrick H.]

Re: 1967 Coupe with A/C Heater Core replacement

I worked on one of these many years ago. You are right; its NOT fun.
Suggest that you also consider buying the right kits to reassemble it once you're done.

https://www.youtube.com/watch?v=R1c0jUS8TzA