What Is Involved With A/C Changeover To R134a?

Go to the Army Surplus store and see if you can buy a live hand grenade. Hold the grenade approx 3" from the low side Schraeder valve, pull the pin, count to 30 and release the lever. About the same effect.

Some people seem to have it work for them. I've tried it twice with miserable results. The longest was 2 weeks with not very cold air, and the shortest was about 2 days with a nasty POW from under the hood, and then the sound of marbles in a coffee can (Spec I saw said 4LBS of Freon, it was really only 2.5...)

The REAL way to do it is to get a new compressor fitted for R134, a new receiver/drier, and as you said vacuum out all the R-12. This has to be done by a licensed tech that can dispose of the stuff properly.

I could have bought 30LBS of R-12 6 years ago for $80. I'm STILL kicking myself HARD!!!

I have had better luck but a system flush is in order.

You gotta replace the dryer, any "suspect" parts and then pull a good vacuum (that holds for at least a few hours). And yes, system efficiency will be less. R134A is less efficient than R12 so if the system was marginal to begin with, you are screwed.

A conversion will work if you prep it proper and don't just pump some "universal" lube in and a wal-mart "kit" worth of refrigerant.

Don't count to 30 on your next hand grenade with your remaining arm.

3, maybe...

Seriously, though, I understand the frustration of a/c systems. Their repair, or professional replacement with an R-134a system, can cost more than an older car is worth.

It's important to remember, on these older cars, that the whole system is full of stuff with finite lifetimes that's been in action since the Reagan administration. Obviously you don't want to remove and replace the heater/AC core unless you really have to -- depending on the car, it can involve slight to horrid disassembly of the dash area, and perhaps some time in the Jacques Cousteau position in the passenger footwell. You want to use compressed air and then a vacuum system to remove the old oil, any debris, etc. and see if they're still good. This can take a half hour or so. But certain parts, like the receiver/dryer, that are easily accessed and known to have finite lives should be replaced. Unless you are really doing this on a shoestring, consider replacing any flex hoses too (hardlines should be good).

The original poster might try to find a sympathetic shop that will remove the R-12. My guess is that they'll charge only a small fee for the service, in return for the gift of the R-12, which eventually gets reprocessed and sold for maintenance of still salvageable A/C system. The reason you shouldn't just release it to the open air yourself, of course, is that it's bad for the ozone layer, which is the sole reason the car makers switched to R-134a. (It too may be slated for eventual replacement -- though it is ozone safe, it is still a fairly potent greenhouse gas; a search is on for effective, safe refrigerants that are innocent on both those counts.)

In some places the stores won't even sell bulk R-134a anymore unless you have the proper license, probably for fear that do-it-yourselfers are just venting the old R-12 to the open air... maybe with a side order of consumer dissatistaction with the $19.95 conversion kits you used to see all over.

Some advice on retrofits (and lots of other topics):

especially Note also that a *lot* depends on how overbuilt the system was to begin with. Economy cars, in particular, are often suspected a priori of having just enough oomph to do their job, without much in reserve, in many ways. If it had Just Enough A/C with R-12, even a successful R-134a retrofit might leave you thinking the cooling is inadequate... though it's probably better than no A/C at all, this time of year!

--Joe

It depends a lot on the car. Some cars, you can pull the compressor, flush the oil out of it on the bench, put new oil in, bolt it up, pump it down, and fill, and it'll work fine (though not very efficiently).

Some cars you will have to replace the evaporator with a proper one in order to get any reasonable efficiency at all.

Some cars you may have to change the expansion valve as well.

BUT... here is the good news.... R-12 prices have come way, way down from the crazy days soon after it was discontinued. There isn't a lot out there, but the demand has dropped a lot too. So you might want to consider what it costs just to reload with R-12 rather than going through the whole procedure with 134a.

If you DO want to do the conversion, talk to someone who has done the conversion on your model car. They aren't all the same, and you can get away with a half-assed job on some models but not all.

--scott

You need to recover the R12 and remove all the old oil from the system. This probably requires removing the compressor and perhaps some additional components. Then flush it well, blow it dry, replace the receiver/drier and possibly the orifice or expansion valve and some hoses and o-rings, and replace the R12 charging connections with R134 connections. Finally, add the correct amount of R134 compatible oil, evacuate and charge with the correct amount of R134. For best results you may also need to replace the condenser with a larger unit. Not exactly simple but it's the best way.

Simple way is to buy one of those conversion kits at Walmart, release all the R12, evacuate the system, and recharge with the oil & refrigerant in the kit. Then when your compressor fails either go without A/C or do it right (see above).

With some help from a friend I did the conversion on a 90 Reatta. I got a lot of good information from

both in the forum and from the staff. Mine cooled quite well....I had no complaint with the efficiency.

But I suggest you do it right, or dont do it at all.

First off you have to decide what is justifiable money to put into old cars. There's the expensive process, where you basically replace everything, or at minimum flush everything with no guarantee it will work. Then there's the cheap way, where you change the fittings, evacuate as much of the old oil as will come out, then refill with R134 oil and refrigerant. Of course any leaks have to be fixed anyway. My mechanic recommended the second method with my '90 Corsica, which started blowing warm. He found no leaks and charged me @120 bucks for the conversion. Just fittings, evac, and recharge. Blew cold for about 3 years, then I heard a hissing from the condenser, and watched the oil stain spread under it. I spent +200 for a new condenser, put it on, charged it up and got nothing for my trouble. The compressor is probably shot. Didn't feel like spending another 300 for a compressor, so I've been driving it for the past 6 years with no air. Up here around Chicago for a grocery-getter it's not a big deal. Kick myself in the ass for buying that condenser. Depending on the heat where you live, you've got to balance cost against benefit. You might try the cheapest conversion on those old cars and see if it works for you. Not much to lose.

--Vic

There are a couple other alternatives. You can still buy R12 on Ebay. Some sellers will want to get a copy of your permit to buy (which you don't have). Others just need a statement that you are planning on reselling it. Keeps the seller out of trouble. You should be able to get some for around $20 a can. You would most likely need three cans. The other option to avoid 134a is to use one of the so called "drop in" replacements, like Freeze 12, it will be around $50 for what you need and is also on ebay. You don't need any permits with it but some retail stores will want one anyway, you won't have that problem on ebay . I have used freeze 12 in two systems without any problems. As others have said, you could and might want to flush the system and then you can put some of the newer oil in it. If all you are doing is getting a system going again that simply has leaked out "too much" freon to work anymore and you want to do as little as possible I'd do the r12 or freeze12. I'd get something like this if I were you.. ebay auction 270393461818 ...It's the first freeze 12 listing that popped up when I searched. I have no connection to it.

NOW they tell me!

I don't recomend doing this, but on my '89 olds ciera I would stick any kind of freon in there. It had r12, r134 & freeze 12 in it at the same time. I'd lose about one pound a year. It worked great until I sold the car.

At the very least you'd want to have the system flushed & the drier replaced along with any gaskets/o-rings to have it done right. Be careful where you go though. The Midas in my area says all they do is recover the old freon and fill it with the new. No flushing or anything done.

It's still $60 a can here for shops in my area compared to $6 for the r134

You can buy solvent to flush the system- do that on all the lines you plan to re-use (blow them dry with compressed air after flushing). Fix all leaks. Drain the compressor (if you're re-using it) of all the old oil but do NOT flush the compressor with solvent (better yet- bite the bullet and buy a new compressor).

Install a new drier (very important).

Its a good idea to install a new orifice tube (preferably one of the variable types, like a SmartVOV brand) or thermal expansion valve.

Fill the compressor with the recommended amount of PAG or POE oil

Charge with R-134 to about 80% (by weight) of the amount of R-12 that the system calls for.

Easier said than done, but conceptually its not that hard. The real goal should be to get ALL of the old oil and any debris out of the system.