1971 A/C o-rings

[Richard L.]

Guys,
The previous owner of my '71 sb coupe installed a new A/C compressor together with a receiver/drier and other items. At the same time it was converted to 134a. He claims the unit performed well once recharged, but that two or three weeks later the freon has pretty much leaked out. He's guessing an O-ring or gasket was improperly installed. So, my question--now that it's 100 degrees in the shade in most of the country--is: is there an O-ring or seal kit I can buy, and if so where? Since I have several vintage Vettes with A/C, I'd like to tackle this myself, including a do it yourself recharge (AutoZone, Pep Boys, Walmart, all carry these kits).
I look forward to your responses and advice.
ric

[Terry M.]

Re: 1971 A/C o-rings

When changing to 134a new (different material) O-rings are required. Did the PO say the O-rings were replaced?

I may be biased, but I believe AC work is not a DIY area in that mistakes can be costly, and a little training can go a long way to prevent these mistakes. If there is a community college in your area I recommend you sign up for a course in Automotive AC. Depending on the course focus they may, or may not have an automotive electrical prerequisite. If there is such I recommend you take it too.

Full disclosure: I instruct an adult education automotive course (not AC) at my local Community College. You are free to say: "That is what I would expect Terry to say."

[Larry M.]

Re: 1971 A/C o-rings

Richard:

The first thing you need to do is determine where the leak is. It could be from a hose, o-ring, compressor seal, or hole in the evaporator or condenser. To do this you can pressure up the system with a can of 134a and then use a soap solution to check all the joints. If no leak is found, then you (or someone) needs to use an electronic refrigerant leak detector and go searching. All AC shops and almost all auto or home AC techs have them. You can also purchase new for around $ 150-200.

134a is a smaller molecule than R12, and requires special barrier hoses and o-rings to prevent leakage....although it has been found that OLDER AC hoses that were in R12 service will absorb the refrigerant oil which can/will prevent this leak-through. 134a also requires a different refrigerant oil and a different dessicant in the drier to perform properly.

To troubleshoot and recharge your system (assuming all the refrigerant has leaked out) will require a vacuum pump, and a set of gages. Plus the refrigerant and any hoses, o-rings, etc that are needed to fix the leak. A new drier may also be needed depending on the time the system has been depressured and idle.

O-ring kits are available from DR REBUILD or from the auto ac forum at http://www.autoacforum.com NAPA also has them if you know what you are looking for and can tell the counter-man. The Chevrolet Service manual for your car has a wealth of information regarding troubleshooting and recharging your system. Get it if you don't have one already. Just recognize that there are some differences between the 134a and R12 procedures.

Larry

[Dick W.]

Re: 1971 A/C o-rings

It is not necessary to go to a Corvette specialty store to buy the O rings. They are available at any of your favorite parts houses, Carquest, NAPA, Autozone, Advance, etc.

[Larry M.]

Re: 1971 A/C o-rings

It is not necessary to go to a Corvette specialty store to buy the O rings. They are available at any of your favorite parts houses, Carquest, NAPA, Autozone, Advance, etc.

I agree. You just need to be know what to ask for, or bring in the old ones for size matching. DR REBUILD and the AC Forum sell the o-rings in a package specific to you car, and they have all of the various sizes you need in one package. That way you know that they will fit. The cost is more for this convenience.....but it is still not very much $.

Larry

[Richard L.]

Re: 1971 A/C o-rings

Thank you for your replies, very much. What/where is the AC Forum, can you give the exact address?

[Larry M.]

Re: 1971 A/C o-rings

Thank you for your replies, very much. What/where is the AC Forum, can you give the exact address?

I provided a computer link in my Post #3. Simply click on the "blue field" and it will take you there. Once there, you can click on another link that they provide to go to their stores. You can also visit their ac forum and ask specific questions and look over problems/answers other are having with their car ac. Excellent site for those of us with ac cars.

Larry

[Richard C.]

Re: 1971 A/C o-rings

Dont forget to use some of this stuff. NYLOG for orings and threads only. #rt201b for 134a. #rt200r for r12. www.refrig.com