Refurbing a Very Early A/C System

[DMC-81]

Hi there,

I am in the process of refurbishing my "very early" A/C system, and I thought I'd document my adventure and what I learned in this thread.

The current state of my system is:

- Completely original
- The OEM Sankyo SD510 compressor engages when manually tripped
- The refrigerant is R12
- The system seems tight and is holding refrigerant, but the amount is unknown

At one point, it cooled briefly, but then stopped cooling and the compressor is not building pressure. After some troubleshooting, I suspect a blockage, but it could also be a compressor failure. I have a primary plan and back up plan to get the system operating again.

My Primary goal is to:
Refurbish my original compressor
Maintain the early style accumulator configuration
Keep the system on R12
Add the high pressure switch and pressure release valve that is missing on my system

And if that doesn't work out, my back up plan is to:
Replace the compressor
Convert to the later style accumulator
Convert to R134a

Here are some pictures:

Compressor:
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Early Accumulator 100743, without the cross on the crossover hose:
image.jpg

Lower condenser hose without the later condenser adapter:
image.jpg

My first step is to pull vacuum on the system before dismantling it to double check for a small leak...

[David T]

Best advice would be to go to an A/C shop and have them check it out.

[DMC-81]

Best advice would be to go to an A/C shop and have them check it out.

Thanks. I got advice from a few shops and the consensus is that the system needs a repair/rebuild.

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Yesterday morning I attached my gauges and a pump and vacuumed down the empty system. It achieved 60hg quite quickly. I read in a few places to go down to 20-30 so I didn't want to go any further. So I closed the low pressure valve and shut off the pump.

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Initial reading:
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I checked the gauges every hour or so and up to 12 hours later, it was still on 60hg. 24 hours later, the reading was 55 -57 hg:
image.jpg

What do you all think? Is this defined as a tight system, or do I have a very slow leak? I suppose the fact that it had gauges attached could introduce leak points. The car was not registered for 14 years before I got it yet it still had refrigerant in the system.

[Bitsyncmaster]

It seems pretty good. Using vacuum is not a perfect test but a good ball park. It's best to change the service valves anyway since those tend to leak with age. You want to pull a good vacuum when your ready to charge. Best to run the vacuum pump for at lease one hour. Then purge the fill hose running a little refrigerant through the open hose end.

[DMC-81]

It seems pretty good. Using vacuum is not a perfect test but a good ball park. It's best to change the service valves anyway since those tend to leak with age. You want to pull a good vacuum when your ready to charge. Best to run the vacuum pump for at lease one hour. Then purge the fill hose running a little refrigerant through the open hose end.

Great. Thanks Dave.

[David T]

Hard to really test for leaks with vacuum. Since atmosphere is 15 psi the most you can go is negative 15 psi or 30" of vacuum. And all you can tell is if it leaks or not, you cannot find a leak that way. A good shop will pressurize the system to 100 psi with Nitrogen and then use a leaktest solution (soapy water and Glycerine) and spray it at the joints to check for bubbles (leaks). Since you are trying to "do it on the cheap" drain the oil out of the compressor and refill with fresh. Change the valve cores. Pressurize with dry shop air to 100 psi and check for leaks at every joint. Fix any leaks and evacuate again for at least 1 hour and then refill with R-12. The longer the vacuum the better, you are trying to evaporate (boil) any moisture out that is in the system, not just suck out all of the air. It takes some time. To speed it up you can use a heat gun on the accumulator to dry out the desiccant. If the hoses are original you really should replace them and the accumulator.

[DMC-81]

Hard to really test for leaks with vacuum. Since atmosphere is 15 psi the most you can go is negative 15 psi or 30" of vacuum. And all you can tell is if it leaks or not, you cannot find a leak that way. A good shop will pressurize the system to 100 psi with Nitrogen and then use a leaktest solution (soapy water and Glycerine) and spray it at the joints to check for bubbles (leaks). Since you are trying to "do it on the cheap" drain the oil out of the compressor and refill with fresh. Change the valve cores. Pressurize with dry shop air to 100 psi and check for leaks at every joint. Fix any leaks and evacuate again for at least 1 hour and then refill with R-12. The longer the vacuum the better, you are trying to evaporate (boil) any moisture out that is in the system, not just suck out all of the air. It takes some time. To speed it up you can use a heat gun on the accumulator to dry out the desiccant. If the hoses are original you really should replace them and the accumulator.

Yeah, I was only attempting to confirm a tight system with this vacuum test as my baseline. I intend to have a qualified shop leak test it after I refurbish the system.

By the way, I'm not trying to "do it on the cheap". I don't know where you read that. I'm trying to preserve as much of the original configuration as possible as I refurbish the system. I suspect that's not going to be cheap.

[cdrusn]

I'm still not sure why you didn't just add Freon in the beginning to achieve proper pressure. You said you didn't know how much Freon you had in the system so you don't know if the a/c wasn't cooling due to lack of Freon. Was your compressor running with the clutch engaged?
Unless you want to just dump money into it, I would go ahead and convert to R134. Dump the old compressor oil and refill with 8 ounces of PAG oil. Get the conversion valves, take out the old R12 cores, screw on the new valves and fill the system with a can with dye in it and a plain can without it running. That will let you know if it is leaking. If it holds to 35 psi on the low side, start the a/c up and see if the clutch kicks in and you have a/c.
I think you are trying to make a reason for buying a whole new system and you may not need to. It might work just fine. What ever you do stay away from the "professional" a/c guys they always want to replace major components. Trouble shoot it your self and then you can go to the "professionals" with some knowledge of what has to be done. As much as a/c guys like to make it seem like black magic, it is just another system to trace out and fix.

[David T]

Yeah, I was only attempting to confirm a tight system with this vacuum test as my baseline. I intend to have a qualified shop leak test it after I refurbish the system.

By the way, I'm not trying to "do it on the cheap". I don't know where you read that. I'm trying to preserve as much of the original configuration as possible as I refurbish the system. I suspect that's not going to be cheap.

I guess I thought that because you are trying to work on it yourself. I see no problem in trying to keep it original but I would try to replace the hoses. If you look hard enough you should be able to do that and have them still look original. Places like Classic Air in Florida makes up custom sets of hoses to duplicate any look you want using modern materials. Send them your old ones and they can duplicate them. Have your shop change the oil in the compressor. I do not like leak testing with vacuum, you just draw in air and contaminants through the leaks.

[DMC-81]

I'm still not sure why you didn't just add Freon in the beginning to achieve proper pressure. You said you didn't know how much Freon you had in the system so you don't know if the a/c wasn't cooling due to lack of Freon. Was your compressor running with the clutch engaged?
Unless you want to just dump money into it, I would go ahead and convert to R134. Dump the old compressor oil and refill with 8 ounces of PAG oil. Get the conversion valves, take out the old R12 cores, screw on the new valves and fill the system with a can with dye in it and a plain can without it running. That will let you know if it is leaking. If it holds to 35 psi on the low side, start the a/c up and see if the clutch kicks in and you have a/c.
I think you are trying to make a reason for buying a whole new system and you may not need to. It might work just fine. What ever you do stay away from the "professional" a/c guys they always want to replace major components. Trouble shoot it your self and then you can go to the "professionals" with some knowledge of what has to be done. As much as a/c guys like to make it seem like black magic, it is just another system to trace out and fix.

Good points. Thanks! I was able to determine that despite normal readings, and the compressor engaging normally, the system wouldn't build pressure... even after ruling out a failed low pressure switch. My A/C shop said that it was either a blockage or a failed compressor.

Either way, it needs repair/refurbishment, and then I'll have it properly charged to spec.

I guess I thought that because you are trying to work on it yourself. I see no problem in trying to keep it original but I would try to replace the hoses. If you look hard enough you should be able to do that and have them still look original. Places like Classic Air in Florida makes up custom sets of hoses to duplicate any look you want using modern materials. Send them your old ones and they can duplicate them. Have your shop change the oil in the compressor. I do not like leak testing with vacuum, you just draw in air and contaminants through the leaks.

That's fair enough. I work on my own car because that's what I bought it for. It's mechanical therapy for me. I've been planning this job off and on for a year, talking to people, learning, and gathering parts. For hoses, I know of at least 5 companies in Florida that can make them. I definitely want one piece hoses, so if I replace them I'll have choices.
I've already contacted a similar company to the one you named and I think I'll have them do some work on a different part.

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Well, I was able to remove the orifice tube today. I used an orifice tool from a rented OEM A/C kit. The tool hooks on the the end of the tube so you can pull it out.

Here's the tool with a new tube:
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Here is how far it was in the pipe:
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Here is my old tube. I clipped on to it with the tool and pulled gently. It came out with no problems and aside from a little bit of debris, it was not clogged or had any ominous signs. Whew!
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