A question about adding R12 1981 Corvette

[FLYTYM]

I tonight a 1981 Corvette with 4600 original miles. The A/C system still has pressure,surprised me after 44 years. I do all my own maintenance on my cars but never really needed to look into an A/C system until now. I bought a set of gauges,found the pressure down a bit so I added 14 ozs of Freon. It bought the pressure up to almost 30 lbs but still not blowing cold. The clutch cycles but won't stay engaged. Could it be the pressure switch? Thanks for any info.

[FLYTYM]

That should read I bought.

[JohnHere]

Did you add 14 ounces of R-12 while watching the sight glass? If so, did it show a lot of bubbles and foam before you started, and did it just clear up afterwards? That would be the way to go if you don't have the tools to weigh-in the refrigerant.

[FLYTYM]

I didn't see the site glass,I did look for one. It might be on the accumulator which is buried behind the WS washer container. How would I check the pressure switch to know if it's good/bad? And also if the system requires 30 lbs of Freon is there a minimum of Freon for the system to work?

[JohnHere]

A sight glass, if your Corvette has one, would be on the high side of the system. Without a sight glass, you'd have to recover the refrigerant, evacuate the system, and recharge it by weight.

A high-pressure switch is normally closed. Check it for continuity with a multimeter. No continuity means the switch is defective.

Conversely, a low-pressure switch is normally open until it's subjected to normal pressures on the low side, which again can be checked using a multimeter.

You must mean 3 pounds of refrigerant.
I'd guess that the amount of R-12 should be within an ounce or so of the under-hood decal specification for the system to operate properly and for the R4 compressor to receive adequate lubrication.

[Cusser]

Disclaimer - I'm not an AC professional.

That stated, I do still have a vehicle using R-12, and I live in Arizona.

I bought tonight a 1981 Corvette with 4600 original miles.

1. Being blunt, if you just bought a pristine 1981 Corvette, you can afford to buy a REAL R-12 service gauge set. If board sponsor ACkits.com cannot order such for you, these can be purchased online. I believe that 1981 is prior to government mandate of different size fittings for the high side service valve, so you shouldn't need any adapters.

2. Pure R-12 is no longer allowed to be sold on Ebay, but some have found it on Facebook Marketplace. Or you could purchase a 609 license.

3. In Arizona, there are still shops that service R-12; you didn't state your location. Such shops also have separate equipment for R-12, a requirement.

[FLYTYM]

Disclaimer - I'm not an AC professional.

That stated, I do still have a vehicle using R-12, and I live in Arizona.

I bought tonight a 1981 Corvette with 4600 original miles.

1. Being blunt, if you just bought a pristine 1981 Corvette, you can afford to buy a REAL R-12 service gauge set. If board sponsor ACkits.com cannot order such for you, these can be purchased online. I believe that 1981 is prior to government mandate of different size fittings for the high side service valve, so you shouldn't need any adapters.

2. Pure R-12 is no longer allowed to be sold on Ebay, but some have found it on Facebook Marketplace. Or you could purchase a 609 license.

3. In Arizona, there are still shops that service R-12; you didn't state your location. Such shops also have separate equipment for R-12, a requirement.

I have a set of gauges I bought,online. I have my CFC UNIVERSAL license so I can buy what I need. Fittings different sizes. Why exactly did you bother to post this? Didn't answer a question,didn't offer any helpful advice. Not sure why someone would bother to waste their time posting such an empty message. How are shops in Arizona servicing R-12 systems when it was outlawed years ago?

[Cusser]

I didn't see the site glass,I did look for one.

I have my CFC UNIVERSAL license so I can buy what I need.

See above about knowing correct refrigerant level in a system. Even with R-12 and a sight glass, adding correct amount of R-12 can be tricky.

Why exactly did you bother to post this?

Because you are incorrect, see below. The only way to KNOW if the system has the correct amount of refrigerant is to pull out the refrigerant and WEIGH it, using a special recovery machine.

How are shops in Arizona servicing R-12 systems when it was outlawed years ago?

Because it is NOT illegal to service R-12 systems. A shop must have separate recovery equipment, gauges, etc. than used for other refrigerant.

Fittings different sizes.

If your high side fittings are smaller, then you'll need an adapter that will work with your vehicle and your R-12 gauge set. Of course there are GM type high side adapters and there are Ford type high side adapters. I'll leave that to you to "figure out" which you'll need.

[FLYTYM]

I didn't see the site glass,I did look for one.

I have my CFC UNIVERSAL license so I can buy what I need.

See above about knowing correct refrigerant level in a system. Even with R-12 and a sight glass, adding correct amount of R-12 can be tricky.

Why exactly did you bother to post this?

Because you are incorrect, see below. The only way to KNOW if the system has the correct amount of refrigerant is to pull out the refrigerant and WEIGH it, using a special recovery machine.

How are shops in Arizona servicing R-12 systems when it was outlawed years ago?

Because it is NOT illegal to service R-12 systems. A shop must have separate recovery equipment, gauges, etc. than used for other refrigerant.

Fittings different sizes.

If your high side fittings are smaller, then you'll need an adapter that will work with your vehicle and your R-12 gauge set. Of course there are GM type high side adapters and there are Ford type high side adapters. I'll leave that to you to "figure out" which you'll need.

Please leave the thread,you have nothing to offer here.

[Tim]

Easy grasshopper, R12 was never illegal to use. They stopped production of it to move on to another refrigerant. Certain year vehicles were mandated to use R134a, but R12 was still legal for other year vehicles.

No one has broken any rules to obtain a removal. 81 Veete would be an original R12 system. If you can find R12, use it. Converting vehicles has been covered many times since 1995. Fittings, oil, label, hose type...

Here is a sample:
https://www.autoacforum.com/search.php? ... mit=Search