Restorer Winter 2025 Article: Refurbishing a 1978 Corvette A/C

[Tom R.]

Very nice writeup and quite timely given my 78 A/Cs are not operational, so a few questions as followup for the authors. In general, if the work to be done is to preserve the originality, as much as possible, how would the refurb differ?

Evaporator: Don't know if there exists a schematic but that would have been helpful to visualize the entire system I was not aware of the evaporator. It was good to learn that the evaporator sits in front of the heater core and housed by the housing...plenum? I have replaced the heater core but that work was from the cabin.

Modifications: Discuss your sources for service replacement parts, particularly the dehydrator. So how did you adjust the tubing on it to accommodate the space and get it to fit? Same with the evaporator fittings...the article referenced "repositioning" the large suction line. I take it the extra Schrader port was left in place.

Compressor replacement: Is it possible to take the core out of the replacement and install it in the original compressor housing? Preserving the label?

Part Sources/Vendors: Where there speciality shops used to get parts or to do work?

I see your article as quite instructive and an inspiration to many 78 owners, especially all those Pace Cars that have sat for years and now in need of A/C attention. And with their 50th anniversary around the corner...may inspire others. Thanks much for your work on this topic.

[Dennis C.]

Very nice writeup and quite timely given my 78 A/Cs are not operational, so a few questions as followup for the authors. In general, if the work to be done is to preserve the originality, as much as possible, how would the refurb differ?

Evaporator: Don't know if there exists a schematic but that would have been helpful to visualize the entire system I was not aware of the evaporator. It was good to learn that the evaporator sits in front of the heater core and housed by the housing...plenum? I have replaced the heater core but that work was from the cabin.

Modifications: Discuss your sources for service replacement parts, particularly the dehydrator. So how did you adjust the tubing on it to accommodate the space and get it to fit? Same with the evaporator fittings...the article referenced "repositioning" the large suction line. I take it the extra Schrader port was left in place.

Compressor replacement: Is it possible to take the core out of the replacement and install it in the original compressor housing? Preserving the label?

Part Sources/Vendors: Where there speciality shops used to get parts or to do work?

I see your article as quite instructive and an inspiration to many 78 owners, especially all those Pace Cars that have sat for years and now in need of A/C attention. And with their 50th anniversary around the corner...may inspire others. Thanks much for your work on this topic.

Thank you for your kind words regarding our article. My apologies for taking so long to reply, I haven’t been able to spend much time on the board lately and didn’t see this post in a timely fashion.

While we will do our best to answer all of your questions, please remember this article was submitted for publication during the summer of 2020 and the actual work was done during early spring 2020, therefore, some of the response may be limited by memory recall and time.


1. “In general, if the work to be done is to preserve the originality, as much as possible, how would the refurb differ?”

Actually, this projected started out as a preservation project and was documented in an earlier article published in The Corvette Restorer Spring 2022, entitled Resealing a Delco R4 Compressor.

As documented in that article, the original compressor was internally damaged. That led us to replacing the compressor. If you are interested and cannot find your copy, let me know and I will send you the pdf file.

To specifically answer your question, I would have sought out ways to re-use the accumulator and I would have explored a few other options for the compressor. I would have searched for another Delco R4 compressor from the same year, or with the same configuration and capacity and swapped the internals in to our existing compressor case preserving the label.

Since 95% of the evaporator is concealed and the existing one was leaking, I would have gone ahead and replaced the evaporator, since repairing aluminum tubing as thin as the evaporator is once it has been saturated with oil would not have been practical.


2. “Don't know if there exists a schematic but that would have been helpful to visualize the entire system I was not aware of the evaporator.”

Basically, there are 4 main components to an air conditioning system. They are Compressor, Condenser, Evaporator, and Expansion valve, or some device to control the flow of refrigerant.

If you would like some additional details about these items and air conditioning in general, check out the Spring 2020 article called Air-Conditioning Service in The Corvette Restorer I authored. This article goes in to more detail about each component, what they do, and service in general.


3. “It was good to learn that the evaporator sits in front of the heater core and housed by the housing...plenum?”

The evaporator would indeed be enclosed in a housing. The plenum would be the duct connecting air to the outlets.


4. “Discuss your sources for service replacement parts, particularly the dehydrator.”

Since the vehicles owner was not interested in having the car judged or originality in general, all parts were generic over-the-counter parts purchased from a neighborhood auto parts store and other than a replacement Delco compressor, were not Delco or GM parts.

If you were interested in repairing rather than replacing, there are still some companies out there doing this work and/or are willing to sell parts or kits. While not a complete list or an endorsement of any company, some of them are Century Auto Air, Century Tool & Equipment, and Vintage Air.


5. “So how did you adjust the tubing on it to accommodate the space and get it to fit? Same with the evaporator fittings...the article referenced "repositioning" the large suction line.”

Very, very, very carefully. I can not say this enough, very, very, very, carefully. While we had some tubing benders available for use, unfortunately they were either impractical due to fittings on the tube ends (spring benders), or didn’t fit between the existing bends. Fortunately, most of the adjustments that were necessary to make the tube connectors line up, required lateral adjustments and not re-bending of existing bends.

Remember, the owner was not interested in originality, we were only trying to position things to allow for a leak free connection. There was no need to ensure the lines were in the same exact location or orientation. We only needed to be able to make the connections, leak free.

In some cases, we made a small die from a piece of wood to allow for making the adjustment without kinking the tubing. This was just a block a wood with a groove in it to fit around the tubing.

The process was to support the tubing with our hands, positioning fingers all along where we would need to bend and applying slight pressure to just move the tubing in very small increments.


6. “I take it the extra Schrader port was left in place.”

Yes


7. “Is it possible to take the core out of the replacement and install it in the original compressor housing? Preserving the label?”

As we completed the work covered in the first article, Resealing a Delco R4 Compressor (The Corvette Restorer Spring 2022), that was my very first thought. Before closing up the exterior case on this compressor, I even took some dimensions of the case.

As I thought more about this, I would have wanted to try this on a similar compressor of approximately the same age and not one bought brand new over the counter. Hence, my earlier comment about searching for another compressor.

Once the owner determined originality was not a concern, our thoughts turned to an over the counter replacement. The original compressor was returned to avoid a core charge, so we never got the opportunity to do a side by side comparison between a 1978 case and a 2022 replacement compressor case.


8. “Where there speciality shops used to get parts or to do work?”

No, all work was done by us and required parts were all over-the-counter from local neighborhood auto parts store.



I think this covers all of your questions and thank you for your interest. Enjoy reading the other article mentioned above.

[Tom R.]

While we will do our best to answer all of your questions, please remember this article was submitted for publication during the summer of 2020 and the actual work was done during early spring 2020, therefore, some of the response may be limited by memory recall and time.

Thanks Dennis for the detailed response. I do understand about the work of 2020 now seeing daylight. The Editor's backlog, if I recall correctly, has been for quite a while. Members see the quality and eager to contribute. I have three in the que since 21/22 and the first of which is about to be published.

But yes, if you would send me the PDF of the 2022 article it would be greatly appreciated. Thanks again...alot to go through here!

[Dennis C.]

Tom, pm sent.