A/C recommendations for '72 BB

[Michael C.]

Hi Everyone, Restoring my 72 LS5 convertible to as close to original as possible. I am at a crossroads on how to approach my factory A/C. The A/C system has been out of the car for over 20 years (worked fine before removal). Original compressor, evaporator and POA valve was stored but ports were open. Factory hoses and condendor are long gone.

Spoke to a rep from originalair.com in Florida and suggested I convert to r134 at this point.

• Send them the compressor and original POA valve for rebuild/restoration
• Replace the original expansion valve with a new a/c delco replacement.
• Send them my original evaporator for pressure test and flush or just purchase a replacement.
• replace condensor with an upgraded one that is more efficient for the r134 but the appearence will not be a reproduction type/look.
• New receiver/drier or send them my original and they can rebuild it.

Though originality is important to me, I do plan on driving the car quite regularly and want a good functioning system.

Thoughts and opinions please as well as other sources I should consider.

Thank You, Mike

[Larry M.]

Re: A/C recommendations for '72 BB

Mike:

My thoughts follow -

1. If at all possible stay with R12 refrigerant. But if you choose otherwise, make sure POA is adjusted to compensate.

2. Send your A6 compressor to Dom Tallarita in California. He is NCRS member and the best in the USA on rebuilding these old A6 compressors. I can provide contact information. Do not send anywhere else.

3. You can check and reset POA yourself if you are handy with maintaining your car. Otherwise go ahead and have them check (and if you go R134a......have then reset) your POA. I have a test procedure I can send you if you decide to do it yourself.

4. Keep your original TXV valve and test it with ice water bath and hot air to make sure it still works. Install a new inlet screen or clean up the screen you have in the TXV (all factory TXV had an inlet screen). I have a test procedure I can send you. Again they can do this for you for $$. Many of the replacement TXV do not work correctly right out of the box. So even if you buy a replacement, test it first before installing.

5. You should be able to clean and test your evaporator yourself. AC cleaning fluids are available at most auto parts stores. Buy end fittings to connect to a hose to pressure it up and test at 75 psig using a small plastic tub to submerge the evaporator core and allow checking for air bubbles. Again, if you cannot do this or do not want to do this, they can perform this service for you for $$.

6. You can either go for a used condenser and have it cleaned and rebuilt or buy a replacement. A few speciality vendors in California may have a used condenser. You can also advertise for one in NCRS Driveline.

7. If you still have your drier, they can rebuilt it for you. They probably have used rebuilt ones you can also buy. I am not certain, but for 1972, the current AC DELCO replacement drier may be very similar to originals for less cost. This is not so for the 63-67 cars, so we generally have an old drier rebuilt vs buying a AC DELCO replacement.........which is different configuration.

8. I would buy replacement hoses that are good for both R12 and R134a. I am not certain there is anyone selling these 72 hoses with the logos on them, but you can check. Again for C2 cars, you can buy with or without logos.

9. R12 refrigerant uses mineral oil for lubricant............but Dom has started using a special Ester oil in his rebuilt compressors. Ester is fine and will work with either R12 or R134a..............but maybe not quite as good as mineral oil if you stay with R12 refrigerant. You could ask Dom to give you mineral oil if you wanted, but for now his standard is Ester. Typical oil for R134a is PAG. But in your case, use Ester or Mineral oil. Just be sure to use the correct viscosity oil in the rebuild. Dom will tell you what he recommends..........and use that viscosity. Dom ships his compressors with oil in them, but you will need to add additional oil to the final system.

10. Use the green HNBR o-rings for your new system.

Do not let anyone except Dom rebuild your old A6 compressor. There are very good reasons I say this. The other alternative is to buy a NEW A6 compressor from ALMA Products in Michigan (or one of their distributors) or buy a Pro6Ten Compressor from Old Air Products in Texas. Both the ALMA and Pro6Ten have metric threads but look close or exactly to originals. ALMA is exact and Pro6Ten is close. They have modern internal parts and chrome plated shafts and double lip seals as all the modern-day compressors now have.

You can do most of your work yourself if you are handy and buy a few AC tools. That is the only way to go in my opinion. But you can also buy these services, but then you are always at a disadvantage when servicing the system. R12 is available at about $40/lb of refrigerant. R134a is about $10/lb of refrigerant. Currently R134a is being replaced by R1234yf refrigerant in American cars and trucks. My new Chevy truck has this new refrigerant. So even R134a is being phased out.

But refrigerant type is your choice. But a system designed for R12 is best operated with R12.........and not a substitute. Just my opinion.

I will help you get your system running if you need/require support.

Larry

EDIT: You may also have to address deterioration in the heater and AC boxes during all these years. Seals and general condition of doors and flappers can also have a significant effect on ac cooling performance.

[Mark E.]

Re: A/C recommendations for '72 BB

Larry, I am also facing this project, so thank you for your helpful post.

Can you post your test procedure for the expansion valve? Otherwise, I'll send you a PM.

Can the evaporator be tested without removing it from the car?

BTW, I haven't sent Dom my compressor (yet), but found him very helpful and generous with his time on the phone.

[Duke W.]

Re: A/C recommendations for '72 BB

Back in the 90s when I went to SEMA every year, I always talked to the AC service equipment manufacturers and asked them about converting to R134a. They ALL recommended to stick with R12 as long as there was supply and said there were huge stockpiles.

Over the years more cars got converted to the R12 or R12 systems were left unserviced, so the R12 supply didn't go down very fast.

Last time I checked, R12 was actually cheaper than R134a, but the biggest problem nowadays if finding an AC shop that still has R12 service equipment.

Duke

[Larry M.]

Re: A/C recommendations for '72 BB

In addition to this, R12 is still produced in Mexico and China. Made in China cans are now reaching American shores and are for sale. Same for R12 produced south of the border. Other countries in this world do not share our environmental concerns and regulations.

Industrial and Commercial refrigeration units are also being upgraded to new designs and refrigerants, so a lot of old R12 is also collected, reclaimed, and reprocessed for sales.

Larry

[Larry M.]

Re: A/C recommendations for '72 BB

Larry, I am also facing this project, so thank you for your helpful post.

Can you post your test procedure for the expansion valve? Otherwise, I'll send you a PM.

Can the evaporator be tested without removing it from the car?

BTW, I haven't sent Dom my compressor (yet), but found him very helpful and generous with his time on the phone.

Mark:

My TXV test procedure comes from the AutoZone Technical Library. Here is the link: https://www.autozone.com/repairinfo/...&subtitle=test

You can test the evaporator while still in the car...........but you need an electronic refrigerant leak tester. I have one, cost about $150. Most refrigeration guys for home or auto have them also, so you could possibly borrow one or rent one from them. Then you would make up end connections for the evaporator core so you can attach an AC gage manifold to one side and pressure up the evaporator core with refrigerant. Using a can of R134a will be just fine for this. After pressuring up the evaporator, you then turn on the car's cabin air blower and use the leak tester to sniff the heater and ac vents and both inside the car and outside around the firewall and ac box. If no leaks are found, you are probably in decent shape. But your gage connections to the evaporator have to be bubble tight so you do not show leaks at the connections.

When done checking, depressure the system. If leaks, either fix the leaking core or replace it with new. But also leak test the new unit before installing.

Don't wait too long on sending your compressor to Dom. He does this almost as a hobby for us Corvette guys and not for any great profit, and his personal health and family's health has not been good lately. He may decide there are other things in life that are more important than fixing old compressors and shutdown this service to all.

Dom is the only one I know that can be trusted to do this job and make the rebuilt compressor better than new. No one else comes close. I have been fortunate to become his friend.

Larry

[Michael C.]

Re: A/C recommendations for '72 BB

Larry, thank you for taking the time to write such a thorough reply! I would prefer to keep the r12 but need to find someone local to me (Boston,MA) that can recharge it. I will definitely reach out to Dom. Thank you!

Mike

[Larry M.]

Re: A/C recommendations for '72 BB

Larry, thank you for taking the time to write such a thorough reply! I would prefer to keep the r12 but need to find someone local to me (Boston,MA) that can recharge it. I will definitely reach out to Dom. Thank you!

Mike

Learn to do it yourself. Or go to an auto AC shop with all your work done and with the refrigerant, and tell them to do a final pressure check with nitrogen, repair any leaks they find (should be zero if you do your homework), evacuate the system, and then recharge with the required 3 lbs of R12 refrigerant you provide them.

If they are competent, they can do this and get you going.

Then have them do a final leak check with an electronic tester. You should be able to get 40-42 F temperatures at the cabin ducts. Maybe better.

Larry

PS: I have helped dozens of guys do this work themselves if they are good mechanics in other mechanical areas on their cars. But that is up to you on what jobs you do and don't want to tackle. But I am here if/as needed. Individual help has ranged from a few phone calls etc to doing phone and email help nearly daily with the same person over a 2-3 month period. But I prefer the short hours.

PSS: A licensed refrigeration shop CANNOT legally charge your system with R134a refrigerant until they change the changing connections (2) to R134a style and place a sticker on your car under the hood that identifies the ac system as having R134a. I have heard shops charging large $$$$$$$$ to do the full/complete conversions for you. It is best to do it yourself and to learn along the way so you can maintain the system later on. Take this FWIW.