Factory AC can work great with R-134A if you know a few secrets

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Jim Kueneman

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Secret 1) The Chinese expansion valves ALL SUCK and flood the compressor. I damaged 3 compressors before I figured this out. Get a NOS one, yes it is R12 but it is really only a couple degrees off for super heat and will work fine.
Secret 2) Aftermarket RV-2 rebuilds suck for the most part. Get a real Chrysler core and pull it apart. You can get NOS piston and rod kits with gaskets very inexpensively on eBay. Make sure if it is an older one with the hole for the check ball and spring is installed! Useful Link:



Secret 3) The '73 front end on the '72 took more like 3 cans to get things working well vs the 2.3 cans I calculated using 80% of what is holds with R12. Charge it so the high side is about 2.2 to 2.5 the ambient air temperature. It got down to about 36F a few minutes after I took this photo. I was cold when I got home. It was 85 and a high sun load.

Secret 4) Use only a NOS shaft seal, they are so much better quality than the aftermarket and work fine with R134A

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I agree. I installed a factory AC from a 71 dart in my 69 cuda, changed the oil and filled it with R134 and it works great.
 
Going through mine soon. I took the bracket off to have it powder coated and want to go through it before I put everything back together. In the video they mention the rubber ball on the spring that can sometimes flatten out and that they use a ball bearing as a replacement instead. When you rebuilt yours, did you have any issues with that? Can you link me to the rebuild kit you used? TIA
 
We started doing them around 2000 never changing any parts. Evacuate, add 8oz PAG oil and charge with R134A, worked fine never had a problem. I did my buddy's car about 15 years ago and I think we add a little R134A about 6 years ago and it still works.
 
Going through mine soon. I took the bracket off to have it powder coated and want to go through it before I put everything back together. In the video they mention the rubber ball on the spring that can sometimes flatten out and that they use a ball bearing as a replacement instead. When you rebuilt yours, did you have any issues with that? Can you link me to the rebuild kit you used? TIA

So that is the rub... the pandemic has dried up the normal seal kits that are available. I have scoured eBay for NOS and spent too much....

You can get piston/rod kits with the necessary gaskets on eBay for around $30 each right now. 2 kits gives you the gaskets. The NOS shaft seal gives you all but the large o-ring for the housing. With that what you need is the o-ring for the oil pump cover and the mentioned shaft seal housing. I have not done it yet but you can get the o-rings from Orings-Online - O-rings and more... Gaskets, Seals, FDA, Sheet, Cord, O-ring Store, Food Grade O Rings, FDA Compliant O-rings but you need to measure them out and figure out what to order. I have not done that yet. Maybe you can find NOS, I have not tried that yet either.

This was a newer housing and did not have the check ball, that was eliminated in later years. I have found a couple threads where it was found that new remanufactured units did not have the ball and spring in them so life expectancy on those would be minimal.

Not a lot of help I know.
 
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We started doing them around 2000 never changing any parts. Evacuate, add 8oz PAG oil and charge with R134A, worked fine never had a problem. I did my buddy's car about 15 years ago and I think we add a little R134A about 6 years ago and it still works.

That is why I never gave up on this... my Coronet was 100% original and 4 years later it will still freeze me out of the car so I KNEW it was possible to work well... The Duster was much rougher and I thought it would be better to replace a few part with "new, better" stuff.... No replacement for original equipment parts, period.
 
Most of the horror stories of what will happen when you use R134 in an old car are just not true. They are just fear mongering. If you don’t fix anything properly, it won’t work right. AC work is different than a lot of other work, but with a little research and some basic equipment, most mechanically inclined people can do it.
 
They say you need to change the condenser because of the difference in design makes it cool better with R134A, and that might be true but 30* below ambient temp is what you are looking for. I have seem 40* below ambient temp most of the time not changing any parts.
 
If worried about R-134A, a drop-in replacement for R-12 are hydrocarbon refrigerants (propane & isobutane mixtures?). I have used Duracool in all my vehicles for decades. Envirosafe is another. HC works slightly better than R-12 and is compatible with all oils. If flushing everything, Hella's PAO 68 is the best oil for any refrigerant. It improves efficiency and doesn't absorb moisture like PAG does. There is concern with HC being "explosive", which is absurd if you understand combustion, yet reporters and hobbyists rant about that. No fire reported after use in millions of cars for many decades. All refrigerants with the accompanying oil spray can burn when punctured, and newer ones (R-134A & R-1234yc) form deadly poisonous gases when they burn. R-134A has long been outlawed in Europe and Canada, and soon in the U.S. R-1234yc is quite expensive and I don't know if conversion is possible or practical.
 
We started doing them around 2000 never changing any parts. Evacuate, add 8oz PAG oil and charge with R134A, worked fine never had a problem. I did my buddy's car about 15 years ago and I think we add a little R134A about 6 years ago and it still works.
How do you flush/ drain old oil?
 
You really don't need to drain all the oil, It does not mix with pag oil or R134a. It just goes and lays in low spots and corners in the condenser, so the pag oil flows through the system with the R134a. I don't like anything with propane in it for refrigerant just because there has been car explosions from leaking evaporators and people smoking. It has been documented and is a fact. The fact is anything can be combustible if the mixture is correct, that has been the argument for years. Propane is highly explosive and in a small concealed area inside a car, I would not want to be in when someone lights a cigarette.
 
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