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Unread 04-13-2010, 11:52 PM   #1
Malachi73
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Converting 1990 Cherokee to R134a

Hey all, trying to convert my 1990 Cherokee Limited, with 4.0L, to R134a. I bought a kit with the adapter in it and screwed it onto the port for the low side of the compressor. Problem is, on my compressor there are two lines coming out. One is hi the other is low, of course. And the way the port comes out of the line for the Low side, when I put the adapter on it, the adapter just about hits the line for the High side, so that I can't get my hose to connect to it to add R134a.

I hope that makes sense. I figure those of you who would know what to do about this have already seen it and understand what I'm talking about. Is there a 90 degree adapter somewhere I gotta buy to make this work, or what?

TIA,
Malachi

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Unread 04-14-2010, 11:18 PM   #2
Malachi73
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Ok, so am I not explaining this right? Or, has no one else ever had this problem? If not, then I am doing something drastically wrong.

Maybe, if I get off early tomorrow I will take a picture and post it to better explain my situation.
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Unread 04-14-2010, 11:29 PM   #3
Chris_Walker
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Unfortunately, you can't just add R134A to your system. Doing so will destroy your compressor and cause all kinds of leaks. You need to first have your system flushed and evacuated by a shop, then replace all the o-rings with the new green ones, replace the receiver/drier assembly, and then you have the system pulled into a vacuum. Next, you add your adapters, and add Ester oil, and then refrigerant. R12 is not compatible with R134a, and the mineral oil used with R12 that is in the lines is not compatible with R134a.

I had a Nissan that had metal filings in the a/c lines because the compressor destroyed itself. The previous owner had not retrofitted the system properly. R134a + R12 turns into an abrasive mixture.
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Unread 04-15-2010, 10:58 AM   #4
My1989Jeep
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Do you have a set of R12 guages? If so then you sont need the retrofit kit. What I did was add 2oz of PAG oil to the compressor and 2oz to the condensor. You have to take off the hose and add it thru there. I used an oil squirt bottle with a long thin hose. And I just added two cans of R134 and wala. Gets down to 50. I didn't vacuum my system but I did add a silver can they sell at Wal-Mart that says it will eliminate moisture and a normal can. Just make sure there is no R-12 in the system. Open the valve to let any out. Goto a pawn shop and see how much they want for R12 guages if you dont have any. I bought mine for $20, that's how much the retrofit kit was going to cost me anyways.
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Unread 04-15-2010, 12:09 PM   #5
Chris_Walker
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^ Do not vent R-12 to the atmosphere. Not only does it destroy the ozone layer, it is also illegal.
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Unread 04-15-2010, 12:17 PM   #6
Nick
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Quote:
Originally Posted by Chris_Walker View Post
^ Do not vent R-12 to the atmosphere. Not only does it destroy the ozone layer, it is also illegal.
X2.

There are hefty fines, at least here in UT.
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Unread 04-15-2010, 01:50 PM   #7
XJH-007
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Tree huggers.

He's most likely doing the conversion because the R12 has leaked out.

In which case I would "hope" he has fixed the leak before the switch.

R12 causes Al Gor....I mean gloBull warming....
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Unread 04-15-2010, 02:42 PM   #8
AZ Jeff
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Originally Posted by Chris_Walker View Post
^ Do not vent R-12 to the atmosphere. Not only does it destroy the ozone layer, it is also illegal.
Aside from the fact that the direct connection between CFC's and ozone depletion was never confirmed by repeatable experimentation (and therefore became a knee jerk reaction by politicians to enviromentalist lobbying), if the vehicle has no R12 in the system now due to leaks, it's already vented out all of it's contents and thus the concern becomes a moot point.
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Unread 04-15-2010, 07:33 PM   #9
Malachi73
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Ok, back to the original question. How do I get a conversion kit to work on this thing?

I was looking at a 92 Cherokee today, and the A/C compressor lines come out the back of it. But, on my 90 the lines come out the top of the compressor. And, again, the low press line is so close to the high pressure line that when I put the adaptor on it there is no room to attach my R134a guage to it. What do I do?

Also, for the record, R134a is totally compatible with R12. All you need to do is recharge R12 system with R134a and you are good to go. The only negative is that sitting and idling it will not cool quite as well as R12 or a native R134a system. Whoever told you that mixing the two creates an abrasive mixture, thereby destroying the system, probably also charged you a lot of money to convert your system to R134a (thereby making a hefty profit). I have personally converted many a system, all with no destruction to the parts (even after years of use).
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Unread 04-15-2010, 07:53 PM   #10
Chris_Walker
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Quote:
Originally Posted by Malachi73 View Post
Ok, back to the original question. How do I get a conversion kit to work on this thing?

I was looking at a 92 Cherokee today, and the A/C compressor lines come out the back of it. But, on my 90 the lines come out the top of the compressor. And, again, the low press line is so close to the high pressure line that when I put the adaptor on it there is no room to attach my R134a guage to it. What do I do?

Also, for the record, R134a is totally compatible with R12. All you need to do is recharge R12 system with R134a and you are good to go. The only negative is that sitting and idling it will not cool quite as well as R12 or a native R134a system. Whoever told you that mixing the two creates an abrasive mixture, thereby destroying the system, probably also charged you a lot of money to convert your system to R134a (thereby making a hefty profit). I have personally converted many a system, all with no destruction to the parts (even after years of use).
The study material for the test that I took to get my a/c certification told me that. As for the adapter fittings, I have no idea. I'd replace the connections on top of the a/c compressor anyway. The shutoff valves in the back of them are usually the first thing to leak. I know mine did. Updating to the later style compressor is even better if you can source one from a junkyard.
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Unread 04-15-2010, 08:12 PM   #11
Malachi73
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Interesting, I worked for a GMC dealer, as a Lube "Tech", back in 92 - 96, and was taught completly different. If I remember correctly, the official policy was as you describe, but all the senior techs said that none of that was actually necessary, just a way to sell more work to the customer (and hence make more money). And, as I've said, I've done many a vehicle by just charging with R134a, and they worked fine for years without any problems whatsoever.
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Unread 04-15-2010, 08:24 PM   #12
Chris_Walker
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If not trying to argue or anything, but I'm just saying if I had to do it for a customer or on one of my own vehicles, that's how it would be done. Years ago they had special concoctions of refrigerant that claimed to be compatible with both, but from what I've heard, they don't work too good. Some compressors may be more tolerant than others though, especially Yorks. But like I said earlier. Some dumb girl refilled the Nissan I bought with R-134a, and while it worked okay at first, over the course of the summer, the Calsonic compressor slowly wore itself down. The mineral oil in the system turned to a thick gel. After that, i'm all for doing it right.
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Unread 04-15-2010, 08:33 PM   #13
Curly5759
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Pick up a 90 degree adaptor from your local NAPA.


As far as converting 12 to 134a without changing the oil, there is a reason that the Manufacturers changed the TYPE oil in the compressor when the conversion began to 134a in the early 90's. PAG oil is recommended and should be used.

I just sat through an A/C update class Monday night. The trainer said the number 1 cause of compressor failure was a lack of Lube caused by an undercharge condition. In a modern A/C compressor, there is no oil sump, so the oil must circulate with the refrigerant. Low charge = loss of lube.

If your compressor is one of the older ones with a sump, it is not as big a deal to be undercharged, but you still need PAG oil.

He also told us the industry is probably going to change to another type of Refrigerant starting as early as 2011, and it is supposed to be fully phased in by 2017.

Curly
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Unread 04-15-2010, 09:08 PM   #14
Tomguy
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I'm in the process of doing this type of conversion myself, but I'm doing it more thoroughly and I have a related question.

I picked up a "new" compressor (Sanden R134a), condenser, hoses, valve body & dryer from a junkyard 1996 R134a Jeep Cherokee CARS vehicle that still had a charge in it. My R12 leaked out all the way so I did the new hoses & condenser as a precaution (plus the new hoses have the service ports built in vs those 90° T's on the compressor). The compressor since I can't really flush all the old oil out of it and I know R12 oil + R134a oil = trouble - plus mine needed a new clutch so I figured killing 2 birds with 1 stone is ideal. I got the hoses also b/c I understand R134a has "Barrier" hoses for the smaller molecules it has compared to R12. I will, of course, replace all O-rings to ensure that tight seal that 250+PSI needs, and I have an R134a gauge set from Harbor Freight (useful tool for only $35 new!). I have a vac pump & compressor to do a proper flush & vac of the system beforehand.

I see the system calls for SP-20 PAG oil. I can't find this at major auto retailers. Can I substitute PAG 46? I have some left over from when I did my 300M. If not, what is the recommended oil fill? Thanks guys!
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Unread 04-16-2010, 06:02 PM   #15
Malachi73
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Quote:
Originally Posted by Curly5759 View Post
Pick up a 90 degree adaptor from your local NAPA.


Curly
Thank You! Thank You! Thank You!

I didn't know that they had such a thing. Picked one up just now for $6.
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