Question about charging 1966 A/C with R 12

[Darwin K.]

Hi,

I have several cans of R 12 and want to charge my A/C system.
I don't know exactly what low side connection to charge through.
I have gauges, and I was going to put the low side gauge connection the the STV connection and the high side to the compressor connector and charge through the low side compressor connector.
Is that correct?

Thanks

[Russ S.]

Re: Question about charging 1966 A/C with R 12

I am not an A/C specialist, but as long as you are on a low side connection I can't imagine it matters which low side one. Is there more than one on each side?

[Edward J.]

Re: Question about charging 1966 A/C with R 12

Darwin, the bigger diameter fitting is the low side. also note that the bigger dia. hose is the low side. smaller fitting is high side, Your gauges will for R12 will only let you put them on the correct fitting.

[Darwin K.]

Re: Question about charging 1966 A/C with R 12

Thanks guys.
My high and low side fittings (7/16) are all the same size as are the hoses.
Tried a fill (12 0z can of R 12) through the STV fitting and found a leak in the STV, probably the diaphragm. Punched another hole in the Ozone.
So, any ideas on where or how to go from here?
Thanks

[Don H.]

Re: Question about charging 1966 A/C with R 12

You can try to rebuild the STV yourself or send it out. I have used Classic Auto Air in Florida many times and received great service. Also you should evacuate the system with a vacuum pump, let sit with good gauges to see if it is tight, then fill. Also be sure you have the correct amount and type of oil in the system. Good luck, Don H.

[Larry M.]

Re: Question about charging 1966 A/C with R 12

Darwin:

As others have said, the STV can be rebuilt. You can buy a kit from many AC and parts sources, or send to Classic Auto Air in Florida for overhaul and testing.

Regarding your AC system:

1. If the system has been apart or depressured for a long time, I recommend that you replace the system o-rings and also the receiver drier. If the state of the system is not known, further disassembly and checking and flushing, etc may be needed. Original rebuilt receiver driers are available, or your original can be rebuilt. ACDELCO also sells a good service replacement receiver drier that looks similar to the original.

2. You need an ample R12 supply, a good gage manifold set, and a good vacuum pump at minimum for servicing your air conditioning system. The 1966 Chevrolet Service Manual also has a LOT of GREAT information on HVAC. Get a copy if you don't already have one.

3. Consider having the compressor rebuilt if the system has been inoperable and depressurized for over a few years. If you know the compressor and compressor seal are good, then let it be. There is a great A6 compressor mechanic and rebuilder here on this forum. I can give you his name if needed.

4. When everything is back together, pull a good vacuum on the system with the vacuum pump and see if it holds vacuum. If not, find and fix any leaks. If it looks okay, put a small amount of dry nitrogen or R12 or R134a refrigerant into your system to build the pressure to around 50 psig or so. Then use a soap solution and check everything again for leaks under pressure.

5. If there are no leaks found, depressure the system and pull a DEEP vacuum for a few hours. This is to remove any moisture as well as any air. Then break this vacuum with fresh R12 refrigerant. Then start the car and AC system and add the rest of the refrigerant. It takes about 3 pounds or 4 cans total. We can help with charging procedures for this step if you are not sure.

Larry

[Mark E.]

Re: Question about charging 1966 A/C with R 12

Larry's advice is spot on.

I've gone through the repair of AC systems on several of my cars over the years as a DIYer. And although I generally like work on my cars (everything from bodywork and paint, to rebuilding trailing arms, and restoring interiors), I've learned the hard way it's easier, less risky, and often more economical to hire a shop in a way where they assume the risk to make the AC work.

Why?

When I restore/replace/install the components myself, if something goes wrong (a leak somewhere; a faulty component), it's my responsibility to fix the problem. I then need to check for leaks, evacuate, and charge the system AGAIN. When the system is finally working, the only warranty I have are for the specific components I replaced that came with a warranty. But if a component fails or a leak develops, guess who goes through the time and cost to check for leaks, evacuate, and charge AGAIN?

Alternatively, I can pay a shop a flat fee to be responsible for the entire job (this means they provide the parts). They assume more risk since they repeat the evacuate/charge/test/replace parts process as many times as necessary to get the system working. And when they're finished, I get a warranty from them for the system to work.

Of course a shop will charge to assume this risk because with older AC systems, the probability of something not working on the first try is significant. Second try too. But think of the time, hassle, and potential $ you might save.

[Jim T.]

Re: Question about charging 1966 A/C with R 12

Finding a shop to work on R12 system cars can be a problem, the shops I have contacted just want to install R134.

[Mark E.]

Re: Question about charging 1966 A/C with R 12

Finding a shop to work on R12 system cars can be a problem, the shops I have contacted just want to install R134.

You might need to provide the shop with R-12. If you don't have a personal inventory (I bought several cases when the writing was on the wall), it's still available on eBay and other sources (my guess is it's shipped from Asia).

I'd avoid an R134 conversion on older Corvettes if possible. Not only does that cost $, R134 is less efficient (i.e. not as cooling), and of course the added R134 do-dads don't look original.