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R-134A high efficency cond/evap with R-12

S

sigtauenus

Active Member
I am rebuilding a factory in-dash a/c unit for my 68 fastback and need to buy a new condenser and evaporator. I also would like the option of eventually going to R-134A and the upgrade to a Sanden or similar compressor. For right now I'm thinking I use the York compressor with R-12 but buying some of the big ticket items such as the evaporator and condensor already ready for R-134A.

The newer design evaporator and condenser have more rows or coils to them (not sure which) which makes it more efficient for the R-134A which is a less efficient refrigerant.

I'm sure these particular parts themselves will work fine with R-12 (I understand some materials are not compatible, typically compressor seals and lubricant), but I am wondering if I use them with R-12 if they will have any issues regarding the gas to liquid cycles as the system operates (example being that if it is too efficient with the R-12 that the system might freeze over).

Any engineers here with thoughts on that?
 
I'm not an engineer, but I do have considerable automotive a/c experience. I don't see any problems using R12 as you mentioned provided the expansion valve is in good working order.
With the price of R-12, I don't really understand why you just don't charge it with R134a since it seems you have done most of the conversion already. Make sure you use PAG type refrigerant oil (get as much of the original oil out of the system as possible), and use the larger service port fittings, and you should be good to go with R134a.
 
"sigtauenus" said:
Is there anything I need to do to the York compressor besides changing the fittings?
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Just get all of the oil out and put PAG oil in
 
"bigb427" said:
With the price of R-12, I don't really understand why you just don't charge it with R134a since it seems you have done most of the conversion already.
Click to expand...

I have done the same thing. And my reason for sticking with R12 is that the system's performance sucked originally, and I didn't want to make it even worse by converting. My system is all new. I've had my system in the shop numerous times (before and after the rebuild) and no one can make it blow cold (really cold). So, I didn't want to further handicap myself by going to R-134A.

I'm still looking for an AC man who really knows how to make these old systems work.
 
I guess I am missing the obvious here. You are actually admitting that the r12 sucks and then convey that 134 sucks more some how. Not picking here , genuinely confused as to what I am missing. I have new cars on 134 that freeze your but off. my old r12 under dash froze my but off. I have new Sanden and new Condenser , drier, hose and so on but they are not charged yet. My new system is for the built for the 134 and Since a compressor is a compressor and does not know what vehicle is turning it I feel it will probably be as cold as my other new 134 cars. I even put a new valve on the evaporator that is made for 134.

My only caution about these things is to go on actual experience and not the pass along old school that r12 can't be beat based on someone probably converting to it without the proper hardware change needed. I did change a car once from r12 to a freon that was neither r12 or 134 and mixes with either one. It was colder....but whenever you put something in a system it it usually because the system needs work, so of course it seemed colder.

With all of that said, I would have stayed with R12 if the cost was still the same but it makes no sense to go with a system that can cost as much as 25 dollars a can (R12) to fill and some day be un available. So making the jump sooner than later seems logical.

...oh gosh to answer the question. Good thinking by switching the parts now. I understand that a good flushing later would set you up for the 134.
No idea or experience on the other question regarding freeze up. I would think a quick call to a few AC companies could answer that for sure.
 
"MarkStang" said:
I guess I am missing the obvious here. You are actually admitting that the r12 sucks and then convey that 134 sucks more some how. Not picking here , genuinely confused as to what I am missing. I have new cars on 134 that freeze your but off. my old r12 under dash froze my but off. I have new Sanden and new Condenser , drier, hose and so on but they are not charged yet. My new system is for the built for the 134 and Since a compressor is a compressor and does not know what vehicle is turning it I feel it will probably be as cold as my other new 134 cars. I even put a new valve on the evaporator that is made for 134.

My only caution about these things is to go on actual experience and not the pass along old school that r12 can't be beat based on someone probably converting to it without the proper hardware change needed. I did change a car once from r12 to a freon that was neither r12 or 134 and mixes with either one. It was colder....but whenever you put something in a system it it usually because the system needs work, so of course it seemed colder.

With all of that said, I would have stayed with R12 if the cost was still the same but it makes no sense to go with a system that can cost as much as 25 dollars a can (R12) to fill and some day be un available. So making the jump sooner than later seems logical.

...oh gosh to answer the question. Good thinking by switching the parts now. I understand that a good flushing later would set you up for the 134.
No idea or experience on the other question regarding freeze up. I would think a quick call to a few AC companies could answer that for sure.
Click to expand...

Mark, you lost me on who you were replying to.

As for R-12 v R-134a, I thought it was generally agreed upon that R-134a was less efficient as a refridgerant than R-12, and that to convert R-12 systems to R-134a and achieve the same amount of cooling you need to upgrade the components (evaporator/condensor) to compensate for the less efficient refridgerant. You could put R-134a in without changing anything but it won't give you air as cold as the R-12. Modern systems work well with R-134a because they come with the more efficient system components already.

I was initially looking at using R-12 because I have a York compressor that works just fine and want to get the car back on the road, and $500 for a Sanden compressor for 134a sets me back more than I want right now, nor did I want to deal with changing the seals/oil to use 134a in the York. That's all moot since I found the ebay deal for $250 that comes with the hoses and drier too.
 
I think I was talking to you :) I can't remember. The point is You seem to know exactly what is important. I heard as well that 134 will work but not as good. If upgraded 134 will work as good or close. That is a GREAT deal.
 
So I'm going in a different direction and am planning on doing the Classic Auto Air conversion and use the factory controls and vents. I just don't feel like rebuilding the factory kit right now. And the price is actually cheaper just to get the conversion than to rebuild with all factory stuff.
 
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