A/C conversion on a 1971

[Ralph Harvey]

We have a 71 that has an original a/c system charged with R12. The main hose was repaired last year and the a/c was workig when stored for the past winter. Now the POA valve is stuck and I'm wondering if the time is right to switch up to R134 as well as replacing the POA valve. The R12 is not available for sale in Canada and R134 might be the answer. I'm getting conflicting views on such an upgrade. I want current coolant however I don't want to compromise the original matching equipment as this is an original . Has anyone converted to R134 and what is involved? Is R134 the answer or are there other options?
Any answers appreciated.
Ralph Harvey # 28843

[Dick W.]

Re: A/C conversion on a 1971

I think from what you say that you have no choice but to upgrade to R-134-a as R-12 is not available to you in Canada. The replacement POA valves differ somewhat in appearance than the originals. R-134 a is the ONLY OEM manufacturer and trade association approved replacement for R-12. EPA has certified several other refrigerants for use in mobile systems, but they do not address efficiency nor do they address the compatibility with materials used in the systems, therefore most A/C professionals do not recommend their use. Plus when it comes time to work on the systems with alternate refrigerants a lot of shops will not touch them.

I have converted several C-3's to R-134-a with success. I only do the conversions when the owner has had a catastrophic system failure (compressor, condenser, etc). Always change the receiver/dryer, compressor oil, and any 'O' rings disturbed. It is a very good idea to flush the system to remove old contaminants. I usually replace the condsensor as it seems to be the "trash can" for the A/C system. Evacuate the system several hours. If possible, I like to leave the vacuum pump on overnight. It may be overkill, but one drop of moisture is all it takes to freeze up a system. Always use the recommended R-134a charge remembering that it takes less than R-12.

Following this procedure we have done several systems that the duct temperature was well under 40 degrees F.

[Tony Roussos]

Re: A/C conversion on a 1971

Where have you tried to find R-12 in Canada?
In the States, only licensed shops can acquire R-12 and service R-12 systems. The consumer cannot find it, but a licensed Radiator/ AC shop can!!

Regards,
Tony

[Jim T.]

Re: A/C conversion on a 1971

Tony I don't know what part of the US you are in, but where I am, R12 can be purchased at auto stores.

[Tony Roussos]

Re: A/C conversion on a 1971

Jim,

That's too COOL.

Where do you live? What stores carry the R-12?

We get RAPED here in the great white north eastern neighborhood of Erie, PA.

I just may visit you when I replace my compressor and refill with R-12, unless . . . do you also have info on A6 compressor rebuild/replacement?

Thank you.
Tony

[Jim T.]

Re: A/C conversion on a 1971

The purchase of R12 does require your presentation of a license. It is not sold to any consumer, only licensed consumers. I have not had any compressors worked on yet. I think there is a place in Florida that you can send your compressor for repair.

[Randy Krohn]

Re: A/C conversion on a 1971

I've got a '72 with AC problems as well. I need to find someone to rebuild my original compressor, as the seals are leaking.

The AC guy that diagnosed the problem says that he recommends that hoses be replaced as well when doing an upgrade to R134. He said he's had several customers who did the upgrade and then found that the R134 was attacking their old hoses after several months. Don't know if it's true or not...

[Jack H.]

Re: A/C conversion on a 1971

The A6 'ususally' leaks at the front seal and, with the special tools called out in your copy of the Chassis Service Manual (available for $20 or so at your local auto parts store), you can pull the front pulley/clutch and replace the front bearing/seal yourself. The factory original bearing/seal was based on sintered metal technology and AC improved the design with a ceramic bearing/seal in later years that's virtually bullet-proof. The ceramic bearing seal is off-the-shelf for something like $10-20 at most auto parts stores...

The factory original hoses (especially the rectangular 'block' shaped fitting that attaches to the rear of your compressor) are 'prized' by restorers because the service replacement hoses differ significantly in terms of fittings and their crimp. So, much of your decision revolves around whether you want the A/C systems to be grossly functional vs. functional and factory concours correct...

On conversion to R134, that's another issue. Of course, R134 is MUCH less expensive than R12 and that's a positive factor. But, most States require a car converted from R12 to R134 to have its fittings changed so the conversion is obvious to refigerant techs and there's no chance they'll mix refigerants... This means further deviation(s) from factory originality for legal compliance--again, it's your call.

Those systems designed from the git-go for R134, typically use 'barrier' hoses (a plastic liner inside the rubber) to thwart molecular migration of the R134 refigerant through the rubber itself. But, the leakage rate with a non-barrier hose is rather slow and R134 is inexpensive to purchase and keep the system 'topped' off....

In our chapter, those who wanted to return their classic Corvettes to active A/C status without affecting the car's factory concours originality went about it this way.

(1) Repair the compressor and install the superior ceramic bearing/seal kit.

(2) Replace ALL of the Schraeder valves with the best commercial grade valves available (figure a whooping $5-10 extra expense).

(3) Use a chapter member who's a licensed HVAC technician qualified to handle any/all refigerants vs. an auto A/C shop licensed to handle ONLY R12/R134 to pull vacuum, verify system integrity, then initially fill the system with an R12 'clone' refigerant that would be classified as an 'exotic'.

(4) Drive/use the car with the exotic refigerant for a month or so, to REALLY verify you've gotten all the leaks and kinks worked out (the R12 'clone' refigerants are pretty cheap).

(5) Once you've demonstrated to yourself, the system is holding and trustworthy, dump the exotic refigerant and fill 'er up with the real McCoy R12....