David H.

my mechanic says he can convert my stock system for about $200. has anyone else done this? good idea? bad idea? i would like some feedback before i do this.

emdoller

Why do you want to convert? Is the current R-12 system working?

68hemi

Don't do it. R12 is the best refrigerant. The mid year Corvette A/C systems are marginal at best for cooling the car's interior so you are going to need every advantage you can get.

I live in Arizona and have had two mid year A/C cars. a 427 and a 327. I sold the 427 car because at 110 degrees with the A/C on I could not keep the car from overheating. I tried EVERYTHING. I had the book that was written specifically for cooling mid years and did it all with no success. The biggest problem is that the radiators in these cars lay down at such an angle that it simply does not get the proper air flow across it. On top of all of this at the time I worked for a guy that had been putting aftermarket A/C in cars in Arizona since 1957 and knew more about automotive A/C than anyone in the country and we could not make it run cool with the A/C on. Granted the Phoenix valley area is a different world and the reason all the big three had proving grounds there.

SWCDuke

Going back to the nineties I have been advised by AC servicing equipment manufacturers' tech reps to stick with R-12 as long as it is available. These were the tech guys who show up at automotive trade shows, not some kid on the phone.

R-12 is more efficient refrigerant than R-134A, so it provides better cooling, and some old R-12 systems require a higher heat transfer capacity condenser to be effective.

The last time I checked R-12 is now actually CHEAPER than R-134A, but the biggest problem is finding shops that still have R-12 service equipment, so keep shopping.

Duke

emdoller

Where are you finding R12 cheaper R-134?

GTOguy

I've done a bunch of conversions, which involved changing the service ports and evacuating and recharging to 75% system capacity with 134. Left everything else alone. The systems worked fine for years, and continue to work. No big deal. If I owned an original, born-with-ac Corvette though, I'd keep it R-12....and avoid the big ugly 134 service ports that look wrong under a classic's hood.

Powershift

That is the question that needs an answer..............

I have done both on Corvettes: R12 and R134a. I prefer and recommend R12, but have helped many folks convert over the years simply because they wanted to and it was their car. But R12 is available if you look.

If your system is not in great shape, get someone like Dom (CF Member) to rebuild your compressor and install a new seal, replace your old o-rings, replace the drier, and charge with R12. Should be "good to go" for 10 years.

If you do decide to convert to R134a, make sure the person doing the conversion really knows what to do. We can help list the steps. A bad conversion is looking for trouble.

Larry

Donald #31176

Ebay has it most of the the time for about $25/ 12 oz can.

David H.

thanks for all of the input. my system works, the compressor comes on just fine, but it just doesn't blow cold. common sense tells you that it needs charging/servicing. my mechanic has done dozens of conversions and is very knowledgeable. he is less than a quarter mile from my house! woohoo! i need to do something, i live in houston, texas, and summer is coming quick!

Mr Fufu

Hi GTOguy,

You mentioned "...avoid the big ugly 134 service ports". What exactly do these look like, and where would I find them?

My '67 coupe has factory A/C. The system works fine. But how do I tell if my A/C has been converted to R-134 at some time in the past? I've owned the car for only 3 years. If it's been converted, where do I find those tell-tale "ugly 134 service ports"?

Do the stock R-12 systems have service ports? How do I detect which refrigerant is in my car's system?

Powershift

Then just get it serviced. Have him check the running pressures and the drier sight glass and add the required amount of R12. Buy it on Ebay. Probably need only 2 cans..........an empty system requires 4 cans.

You could also have issues with the expansion valve or POA valve. Converting to R134a will not help these but will make them worse unless they are fixed/working correctly. The POA valve should be removed and reset for a correct/proper R134a conversion...........was your mechanic planning to do this?? Also need a new drier with the correct molecular sieves for R134a and to also install the green HNBR o-rings. Was this planned?? Also R134a does not like mineral oil refrigerant oil and requires Ester Oil (or PAG oil for brand new systems) to keep the compressor happy. Was your mechanic planning to empty and clean and recharge the oil system.

Also to do it legally, the Schrader valves need to be changed to R134a service ports and a R134a charging sticker needs to be installed under the hood.

You can do what you want to your car. We have provided you good advice both pro and con on converting. But mostly con

Larry

Powershift

There is no good/easy way for most of us to tell what refrigerant is in a car's AC system. You can guess at it based on temperature and pressure. Really good AC shops have a gas analyzer that will tell the difference..........manily because they do not want cross contamination.

Most/many folks do not follow the law and change the service ports when they change refrigerants. They can be purchased and installed. Ebay probably has them. R12 uses typical Schrader valves, but R134a uses a special/different size and configured port or valve. The threads are also different on the ports/service connections for the gage manifolds, etc.

I'll try and find you a picture of these valves and post it a bit later.

Larry

EDIT: I helped a guy on here (CF) a few years ago that purchased a partially full can of R12 for his car on Ebay.............except that the can contained a mix of R12 and R22. Needless to say the recharge and return to service did not go very well until we figured this out. Mixing refrigerants is bad news unless you really know what you are doing.

emdoller

Ports:

emdoller

If you have the quick connect ports, the system was likely converted. "Legally" that's the way it should be done. I've seen cars converted and the R12 ports kept the same. Most of the time they are switched over.

To be sure you can take it to a shop.

Lastly, Larry knows what he's talking about!! He's helped me quite a bit so trust his judgement.

Ed

Powershift

Ed:

Thanks for the pic. But for your 1967 car (and mine ) the low pressure and high pressure service ports are the same size. FORD used the two different sizes back then............and the industry finally changed to make this standard on all the later year cars using R12 refrigerant. I am not sure of the exact year this change was made, but probably around the early 1980's.

I keep a supply of all these conversion fittings and sizes in my garage just to be sure I have what is needed to help friends and neighbors, but I don't remember all the sizes and when they changed. Not enough good brain cells left anymore.

Larry

emdoller

Good catch! I just grabbed the one picture I had.

GTOguy

Larry has very valid points, especially with the POA valve used in these early systems. The ones I have converted were all 1980's vehicles with orifice tubes.....a very simple conversion. Not the same system as yours. If it were my car, I'd have it professionally serviced and stick with the original R-12. You might pay $20 more in refrigerant costs at the end of it all, but the integrity of your system will be intact.

Powershift

Here is a pic with EPA changeover sticker and the connectors for various cars. Your 1967 Corvette will need 2 of these 4 connectors: 7/16 to HI and 7/16 to LOW.

http://rechargeac.com/products/retro...it-kit?lid=492

Then you (or your service guy) needs the R134a color-coded connectors to attach their manifold hose set to these R134a engine compartment connectors.

Larry

SWCDuke

...haven't checked lately, but a shop in SoCal where I had a R-12 car serviced a few years ago charged less per pound for R-12 than R-134a. It was a pleasant surprise. I suppose his price for R-12 was less than R-134a, and rather than gouging, he passed the savings on to his customers.

Very, very little R-12 is being used nowadays. Most R-12 systems have been converted to R-134a or the cars are beaters and not worth enough to service the AC systems. Apparently there is still a lot of R-12 out there so lots of supply and decreasing demand means lower prices to get rid of old stock, but at some point when it gets really rare the price will skyrocket for those vintage car owners that want to maintain their R-12 systems.

Duke

GTOguy

I've noticed exactly this in the industry. In the late '90's, R-12 went through the roof and people hoarded it. Most of those cars were used up and are now gone. The few remaining R12 cars are usually valued collector cars. I've picked up R12 at swap meets for $10 per 12 ounce can. A buddy of mine scored a 30 pound tank for $50. It's out there. Remember when it was so cheap people used to blow their freon horns with it at ball games? And use it to cool down their warm beer?