R134A AC retrofit

Unless you own recovery equipment there is no legal way other then taking it somewhere with the equipment. Of course you can just vent it yourself, which is what I would do since the whole R-12 issue is over and the ozone hole has closed back up. As to retrofit, I would not use 134a but would go with Freeze-12 or one of the other common, so called, drop in replacements. Going that route eliminates the need to "retrofit". Just flush the system if you think its contaminated from the compressor seizing and put the Freeze 12 in it. I've used it in a 64 T-bird and 92 Ford explorer and it worked great in both. Neither had the compressor seized so I did not flush them or change the oil.

Reply to
Ashton Crusher
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My (Freon) AC compressor finally seized up. Its in a 1979 Porsche 928.

Any recommendations about retrofit kits? Either good or brands to avoid.

I'd like to do as much of the installation myself as possible. So the first thing I'll need is to find the best (legal) way to pump out the old system before I yank the old parts out.

Reply to
Paul Hovnanian P.E.

The retro kit has new gaskets & seals which should be replaced. Sure you can just remove the old stuff and put in some new freon, but if you don't change the seals etc they'll probably start to leak within a couple of years.

Reply to
CEG

It's also a good idea to replace the drier during the conversion.

Reply to
CEG

If you can find a shop with R-12, that's the way to go.

Reply to
Steve Austin

Check the system pressure cold. If there's no actual freon IN the system, there's no reason to bother pumping the thing down.

On the off-chance that there's actually something left in the system, take it to a place with a recovery machine and have them pump it out. It won't cost much. My guess is, though, that you won't need to do that.

While you have the thing apart, change the dessicant pack and all the rubber hoses. The price on R-12 has fallen down to reasonable levels these days and so there's really no reason to use anything else.

--scott

Reply to
Scott Dorsey

No shop in this area carries R-12 anymore. Maybe where you live it is different.

There are a lot of admonitions about products such as Freeze 12, but some people seem to use it successfully. The biggest admonition is, the last time I had an issue, that the warranty on the compressor was in question.

I did a total conversion to 134a and it worked fine...but I replaced compressor, o-rings, accumulator drier, etc, and flushed it.

Reply to
hls

Check E-Bay. Demand for the stuff has dropped off and people aren't hoarding it any more. So it's a lot more expensive than R134A but a lot cheaper than doing a proper retrofit with a new evaporator, etc.

Freeze-12 is mostly propane. It's explosive. It's probably fine as long as the system never leaks, but it gives me the willies.

Did you change out the evaporator for one with a larger area? I have found that if you don't do that, you get a system that is reliable and works, but doesn't cool as well as it did with R-12.

--scott

Reply to
Scott Dorsey

Actually, I believe Freeze 12 is mostly R-134 with some R-something-else (I forget which), about 85%/15%. The something-else is supposed to be compatible with the R-12 oil so that you don't have to flush or change the oil. It'll probably work OK until the something-else leaks out and you're left with R-134 and incompatible oil and your compressor seizes.

Many of the other R-12 substitutes are indeed propane/butane/etc, tho, so be careful.

Best bet in the long run it to do it right.

Reply to
M.M.

We converted all our old farm tractors from R12 to R134A. The only parts replaced were the receiver-drier and the expansion valve. Performance has been at least as good as with R12. The only problem is that the older tractor (1981 model) has to have a can of 134 added once a year usually in July when performance degradtion is noticeable). I suspect it is leaking through the seals on the old two cylinder york type compressor, but the leak is so slow, I don't feel the need to look for it. The tractor sets for months at a time, so I don't think it is suprising there are seal leaks.

Ed

Reply to
C. E. White

I didnt change the evaporator core in this case, but it turns out it wasnt necessary. It cools just fine.

Maybe different vehicles would have different cooling demands (vans, pickups, large cars) but in this case the original worked fine.

Reply to
hls

It is 80% R134a and 20% R142B, according to the data I have. R142B is chlorodifluoroethane, and I believe it has also been outlawed in the USA.

Maybe Freeze 12 has already replaced it with something else.

As Scott said, some of these things are flammable or explosive.

Some manufacturers, IIRC, specify that products like Freeze 12 are not acceptable for use with their hardware.

Reply to
hls

I wouldn't refit. R-12 is still out there and available. Price has come WAY down in the past 8-10 years. You will need to flush the entire system, replace the compressor and drier. Leak test it. All of the above can be done by you. As for recovering the R-12, just go to a good shop, explain that you will be coming back to get it charged and they will give you credit for the r-12 they pull out. Then when you recharge it will only cost you the difference in the amounts used.

NONE of the retro kits will cool as well as the R-12 and many of them are just plain JUNK from the word go. As for the "drop in replacements" for R-12. There are actually none that are classed that way. They all require you to flush the system and change parts to perform and even then they don't work anywhere close to the original R-12.

Reply to
Steve W.

I have had really good luck with these guys

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The earliest 928 they reference is 1980, but they may still have parts for your model.

Reply to
hls

Well, the compressor is probably toast. So I'll be throwing a new one in regardless of whatever type of refrigerant I select. I'm guessing that this will be the most expensive component in the system, so a new dryer and assorted plumbing will go in as well. So saving a few bucks on strange refrigerants isn't a big issue.

That said, it comes down to questions of performance and quality. R12 has a better heat capacity than R134A (I've been told). So if R12 were easily available, I'd just go with that. I'm not familiar with Freeze 12. If it outperforms R134A, it might be worth considering. But if there are warranty issues with the new compressor, I'd rather avoid it.

So it comes down to the quality of various R134A retrofit kits. If none of them work well with an existing evaporator (the one part I don't want to dig out of the system) then I'll have more thinking to do. But if there are a few brands that are OK (or to be avoided), that's what I want to know.

Reply to
Paul Hovnanian P.E.

Its not a "kit," its a process.

-Evacuate old refrigerant

-Flush all hoses, evaporator, condensor to remove all old oil and siezed compressor debris.

-replace compressor (go with a new one that's made for R-134a- Sanden is a good brand).

-Fill compressor with either double-end-capped PAG or a POE oil made for R134a (most new compressors come pre-filled with oil).

-Replace all O-rings and gaskets

-Replace expansion valve if it is at all suspect (don't flush the old one if you think its good, though).

-Replace drier

-Pull a vacuum, let stand for at least an hour to check for leaks, overnight is better.

-Recharge.

Reply to
Steve

Paul, take a look at the site

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These guys have been very helpful to me, and I have used them for several years. They have a forum which addresses most of your questions. Or just call them for advice.

If you dont want to buy from them, fine, but they are a good source of very correct information.

Reply to
hls

AFAIK, the evaporator almost never has to be replaced when converting to R-134a. If anything winds up being under-sized, its generally the condensor and that can often be alleviated with an extra electric fan instead of a new parallel-flow condensor. I've got two 60s-vintage cars converted to R134a, and I didn't replace either the evaporator or condensor on either car. One of them doesn't even have an auxiliary electric fan and it works very well. The other had a smaller condensor so I put a pusher fan on it but it probably wasn't necessary given the low head pressures (for R-134a, still higher than R-12) I see on it.

Reply to
Steve

Just looked at my buddies 80 928 today, his already has a pusher fan from the factory.

Two things; his compressor seized making condenser replacement mandatory (you can not adequately flush a condenser) , and being a serpentine condenser, it won't work very well with R134. better to swap it out for a new parallel flow unit for efficiency and warranty sake.

Reply to
aarcuda69062

Auto makers have issued technical bulletins about conversions to R-134a. For some models, they recommended little more than improving the air flow over the condenser, such as by adding shrouds, upgrading the radiator fan, or even adding a pusher fan. But for others they wanted the original condenser replaced with a higher capacity one, both to provide good cooling and to keep the compressor pressure below ~300 PSI. I don't remember seeing anything about replacing the evaporator coil.

If the A/C is regulated with a TXV, it may be practical to change just the dryer, oil, and refrigerant and obtain good cooling, even though there are TXVs made specifically for R-134a. But if the A/C is controlled by pressure, at the very least adjust the pressure cycling switch to turn off at about 21-22 PSI rather than 25 PSI, or else the air may never blow out cooler than 50F, and it's probably desirable to also replace the orfice tube with one calibrated for R-134a. In very hot climates, a condenser upgrade may be needed if the passenger cabin is large.

Around 1995, after the A/C compressor seized for the third time, I converted my 1978 VW Rabbit to R-134a by replacing everything but the TXV, evaporator, and the metal ends of the hose assemblies (had new rubber installed on them). I put in another York inline compressor, a rebuilt, but many newer design compressors aren't known for being reliable when rebuilt, so it may be a good idea to buy a brand new one (prices vary greatly, and some places may charge only $100-200 more for brand new than what others charge for rebuilts). Because I lived where 115F was common in the summer, I also changed the original condenser for the largest flat tube serpentine model sold by J.C. Whitney. Co. Cooling performance was very good, even without window tint.

Reply to
do_not_spam_me

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