Converting to R-134?
 

I'm wondering how to convert the AC to R-134. Is it just a fill it up kind of thing, or is there anything special that's got to be done to the system first (besides converting the fill valve). It is currently completely bone dry. Also, where can I find the compressor lubricant, or do those r-134 cans at the auto parts stores have lube in them already?

I'll probably replace the o rings at the hose joints on the compressor, as it looks like, by the oily mess, that the old stuff was leaking there. I might have to hunt down another compressor if it turns out it leaks, but I want to just try filling it up first to see.

Any help is much appreciated.

if you can, pick up some Duracool - 100% compatible with R12, no conversion necessary. just fill and go.

Fix the leaky o-rings, put some pag oil and 134 in, done. The oil should be on the shelf at any auto parts store right next to the 134. Throw some dye in there too.

Where is the low side (charge) connection? Is it on the compressor? If so, I have a few suggestions.

My way is often different from others, it may not be popular, but it works, and doesn't cost and arm and a leg. I think I have $25 invested in my A/C, and it blew cold today. Or, you can buy a whole bunch of new parts, and have great fun changing the expansion valve.:rolleyes:

Tell me more about changing the expansion valve... I've got to fix the system on an '87 924S I switched over to 134 - held pressure OK, but stopped working I believe due to a clog, presumably at the orifice or exp valve, whichever it has?

Same as Eldoraldo; they make a drop in R12 replacement you can get at air conditioning parts stores. Most people don't know about it. I guess then the makers of R134 would not have made all that conversion money. Keep in mind "low side" in on the bottom of motor, drivers side. Not the top connection, that's the high side.

Kyle, How tough was that to do, just plug a hose in, done?

From what I understand. Correct me if i am wrong. The Duracool mixes perfectly with the old R12. So if you still had R12 in your line it would kinda be like adding more R12. So you shoudl n't have to do anything. At least that is what I plan on doing if my car needs any freon

I wouldn't know anything about the expansion valve, i didn't mess with it. I have heard it's a bear to get at. My point was that you don't HAVE to change anything but the low side connection to charge, and 134 will work just fine in our system.

If you think you have a clog, then I would disconnect the hard lines, both high and low, and blow some denatured alcohol through the lines with compressed air to clear the clog.

Dave, you are correct, duracool is a fill and go. If the system is empty, not just low, then 134 can be added if you use pag oil.

subzero or duracool is the way to go
r12 is always better at cooling than 134 so id stick with it and just top off /add, to proper pressures for desired temp range any one ever try to pull 134 down to 32 deg at the vent takes about twice as long

just my 2 cents

Random, how can we tell if we're out (empty)?

zero pressure on low or high side indicates empty

schrader valve like on tires push it in if cool stuff comes out youre not empty

OK. Car sat in a garage for a while before I acquired it and the AC has always been fairly sketchy.

I'll try that test on the low pressure side. As long as it's not gonna blow up on me. :P

What is pag oil? Is that a brand or a type? And is it something that you can get at pepboys, or would I have to go somewhere special?

Does duracool or regular R-134 work better, and which is cheaper? Does duracool require separate oil, or does it have oil added to it? And is duracool easy to find, and does it require a fill valve conversion?

all i can answer to that is this...

duracool, or products similar to it.. maybe not exactly that brand - are easy to find.. and no conversion is required.

pag oil is a type of lubricant used in ac systems, ester is another type of oil, which is commonly used with 134. Anyway, what you are to likely find in your system right now is pag oil. The R12 compatable stuff can be found at most any parts store. It is more expensive than 134, IIRC twice as much, but still that's only $6 a can more.

The main reason I did a swap was to ease the hassle of charging. When the low side is on the compressor, it can get very tight trying to get a hose screwed onto the fitting. IIRC, I would have to swing the compressor out of the way, put the fitting on, put tension back on the belt, charge, move compressor back to get the fitting off, then tension the belt again. Way to much work, when you can charge it with a simple plug in the 134 quick connect, then take it off.

YMMV, good luck.

Thanks for the tips, Matt!

Actually, there's not really much of anything left in the compressor, since I completely disassembled it and cleaned it out. Just amasing how they are built. It's pure genius how they pack so much commpressing hardware into such a small unit. But the lubricant was a thick yellowish goo if that helps identify it.

Is there any compataability issues with using ester?

And thanks everyone for the info. I'd be lost without ya. :)

Yes, you should not mix the two as they are not compatible. There is a third lubricant that mixes with both of those, I think it was called caster. If you change the lubricant, then you need to flush the system first. Someone told me they found an ester oil that is compatible with pag but I haven't ever verified that is correct.

If your compressor ran R12 last, then it had ester oil. Pag oil is used with R134 systems and is not compatible with R12 or all components of all a/c systems. It does however work with the components of the 944. If you decide to swith to R134, you should empty all the oil you can from the system including the compressor; flush the components of the a/c system with a good flush and then put in the R134. You should then use the pag oil and mark your system accordingly that you have R134 and pag oil. Of course changing the fill plug should tell someone working on your car that it has been converted to R134. When you are ready to fill your system, put gauges on both high and low side and see what the readings are. The values you are shooting for are: 30 and 212 although with R134, the values may be slightly higher. You probably will not get those exact values but if you are close and the air feels cool, you are fine. The thing to look out for is you don't want the high side to be real high and the low side to be real low...then the expansion valve is plugged keeping the freon from passing through it and keeping the high side under extreme pressure. If that is the case, you need to either clean it or change it. Since it's under the dash, it's a pain to get to so hopefully that is not the case. With you not knowing the condition of the expansion valve, I would not recommend using only the low side gauge..make sure you test the high side as well. It's best practice to always change the dryer after you open the freon system. Before filling with freon, it's best to vacuum the system and leave it to make sure there are no leaks and you have removed the air/moisture in the system. If you skip that step, your a/c system will still work but not be as efficient and run more. The 944 is equipped with a site glass like most R12 systems were. This site glass was used to determine if the freon was low in the system as you would see bubbles. If you convert to R134, do not depend on the site glass to determine if the system is low as R134 is cloudy by nature and it will look as though it is always low.

Thanks for straightening me up, razor. I had em bass ackwards. Its been awhile.SmileWavy

Thanks Razor. Can you tell me what the different oils look like? I assume it had R-12 in it, but the PO was kind of flakey and could have done anything to it and I wouldn't know. The stuff that was in there was kind of thick and yellowish.

I assume that the R-12 compatable stuff will work with ester oil, in which case I can just fill it and not have to flush, right?
But if I did flush it, what does one use for that?

I actually have a couple of cans of R-12, and there's a place down the road that sells it. Don't know how much, though. Just using R-12 might be easier if it doesn't cost too much (considering the fact that it could all leak out and I'd have to start over).

But I guess I could vacuum test it, but how does that work (just pump it up and see if it holds?)? I got a vacuum pump, just would have to figure out how to hook it up. BTW, does the fill valve come out of the fitting like tire valves do? I could remove it and be able to vacuum the system from the fill fitting. :confused:

Help! this is getting complicated! (rolled down windows are starting to sound good again :( )