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Changing a/c from R12 to R134a on 93 XJ

B

br1anstorm

NAXJA Forum User
Location
United Kingdom
I have browsed the forum threads on this subject, and there is almost too much information. Some posts give perfectionist advice (replace everything!), others suggest a variety of alternative solutions.

Here's my situation. Until now I have managed to keep the a/c system on my XJ - a 1993 4.0 litre - stock, as I managed to find a cylinder of R12, which is now no longer obtainable or legal. But the condenser now has a serious hole. I have to replace it. So I think the time has come to bite the bullet and go over to R134a.

Now.... there are no junkyard sources for used XJ parts over here in UK, and new parts are hard to find and/or expensive to ship from the US. So I don't really want to replace the entire system. But I do want to do the essential, or necessary changes, as I want the a/c to continue to run reliably. I know I need to get a new condenser and the receiver/dryer, and change the connector fittings. Ideally I'd like to keep the compressor (very costly to replace), and all the hoses (hard to source replacements).

Are there alternative types/part numbers for replacement condensers? I have seen references to a "parallel" condenser in later XJs - what is that, is it better, and would one fit in a '93?

Any warnings or advice on what other parts (eg expansion valve) that have to be changed, and also on what else to do - or what not to do - when converting from an R12 system to R134a? I have incidentally already replaced my radiator, about a year ago, as that had virtually disintegrated. Pity I didn't think of replacing the a/c condenser at that time!
 
In general with a hole and not a compressor hail put you shouldn't have to worry about the expansion valve. But you will want to replace the accumulator/dryer as it acts as a filter and absorbs moisture. I converted my 89 this year, but I did the compressor, expansion valve , dryer and low side hose. It hadn't run in 6 or more years and had no freon in it.

I did also replace all of the o-rings at every connection.

It has been working fine ever since. I also flushed it when I had the hoses disconnected, which is a key part in determining the overall health of it. If you shiny metal bits that's bad obviously.
 
You need to replace the drier anytime the system is opened for an extended amount of time (more than a day). Otherwise just replace what's broken, put it under vacuum, recharge with 134a and then fix it as needed
 
ehall said:
You need to replace the drier anytime the system is opened for an extended amount of time (more than a day). Otherwise just replace what's broken, put it under vacuum, recharge with 134a and then fix it as needed
Click to expand...

did this when i bought my heep a few years ago. lower hose was broke, replaced it and the drier, pulled vacume and then filled with 134a.
have had great ac since.
 
Thanks for comments and advice. One specific question. Is the a/c condenser part number for an XJ the same, irrespective of year? I have the OEM part no 5600 2957 for the condenser to fit my 93 vehicle (which was of course originally filled with R12). Is a replacement condenser the same - or are there new/improved/different ones now available which will fit? I'm still puzzled by references to "parallel" and "serpentine" condensers in some of the online sites.
 
Being in the UK complicates things a bit. For one thing, 93 was the year of the mandated switch to R134a in the USA, so anything 93 and up would be valid for R134A here, but I don't know about condensers on your side of the pond with systems still using R12 in '93. Also, some parts were mirrored for RHD but some weren't (in the USA the condenser hose connections are on the right side of the vehicle [USA passenger side]). Short version is the USA knowledge doesn't really go far. If you google for "xj parts catalog" you can get the catalogs as PDFs and compare that way, but I don't know if they are complete for RHD.

My advice is just make sure the hose connections are in the same place and are the same size and style. Otherwise you will need to get new hoses made.
 
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I just did the conversion on a '90 XJ but went ahead and scavenged new hoses off a '95. Here is what I found:

This is a GREAT site to get parts: http://jeepair.com/ and they will ship worldwide.

1) The oil used for R12 is not compatible with R134 so any parts you reuse will have to have the oil drained. You can flush the evaporator with compressed air and get most of it but I recommend using an AC flush kit as well which is simply a can of compressed liquid that you can spray through the evaporator. You need to replace that oil with "PAG" oil like this: http://jeepair.com/tools-more/oil-pag-46-eight-ounce-bottle.html.

2) You should always replace the drier since its role is to eliminate moisture and the moment you open up the system, it will likely saturate. I used the following part: http://jeepair.com/accumulator-driers/cherokee-filter-drier.html

3) Go with a parallel flow condenser. On your current XJ, the compressed gasses flow at high pressure through a serpentine condenser (gas goes in one side and flows through the condenser to the exit port). This works ok for R12 but R134 operates at higher pressures so this becomes a bottleneck. A "parallel flow" condenser connects all the cross paths together so that when the gas enters, it can spread out across all the paths to the return port. This lowers the pressure and is more efficient for R134. JeepAir also sells these but you may need to adapt them http://jeepair.com/condensers/14-x-18-universal-superflow-condenser.html

4) If you use your existing compressor, you will need to add some adapters like these to get the correct connectors for R134. This type of adapter will bolt onto your existing compressor and provide the correct fittings: http://jeepair.com/fittings/tube-o-suction-discharge-fittings-with-r-134a-ports.html

5) After all this, expect that the system will blow cold but not as cold as before. I changed everything except the evaporator and now regret it. The reason is that I found that the exit port on an R12 evaporator is smaller than on an R134 system so the gas does not decompress as much, thus is less cold. Probably ok in the UK but when the temps rise to 102 degrees (39 degrees Celsius) in the Houston summer, I have to run it at full blast just to keep it moderately cool. Having this constriction also leads to higher pressures on both the low/high side so you can't really optimize and instead, have to charge it to a "compromise" position where the low side is lower than recommended and the high side runs higher than recommended. It will work but it is not optimal.

I intend to fix this in the future by purchasing a new evaporator as well as a new expansion valve for a '95 to get the pressures/temps perfect.

To further clarify, I did use hoses off a '95 so before buying any of these parts you may want to email JeepAir to confirm that the connectors for the drier/condenser are the same fittings.

HTH
Todd
 
Last edited:
ehall said:
Being in the UK complicates things a bit. ......
I don't know about condensers on your side of the pond with systems still using R12 in '93. Also, some parts were mirrored for RHD but some weren't ........ If you google for "xj parts catalog" you can get the catalogs as PDFs and compare that way........
Click to expand...


Ooops. I should have said, but didn't, that although I am in UK my 93 XJ is a US-spec, LHD vehicle. Long story short, I got it new from the US originally to use in the Middle East (where LHD was needed), and when I eventually returned to the UK I brought it in with me as a personal import. So it needs standard US-model parts. So those parts which are "handed" for LHD, like the radiator and condenser, are not easily found in UK.

I have various Jeep parts catalogues as PDFs, and I often check with Rock Auto.

tjmotter's post is hugely informative and useful. I'm off to check out that Jeepair website. As their stuff is evidently designed for US/LHD vehicles, items like condenser should fit my XJ without needing modification.
 
In re-reading your post, I thought I would add a couple of more comments to ensure you have the complete picture.

1) the expansion valve should match the year of your evaporator so if you have a '93, stick with a '93 expansion valve. The fittings to the compressor/drier are the same but as I noted in my first post, an R134 evaporator has a bigger outlet port than the R12 unit.

2) My '93 also had R12 so I believe that the changeover occurred in the '94 model year.

3) The parts from a '94 through '96 will use the same threaded hose fittings and can be connected to your R12 hoses but from '97 on, Chrysler moved to a newer style "press in fitting" that uses a plastic retainer (similar to those used on the fuel rail) so buying parts from this era will force you to replace all your hoses.

4) I forgot to mention but while you are ordering parts, make sure to buy a new set of o-rings. They are cheap but I have heard reports of people sticking with the old o-rings and having them fail. I don't know if there is a compatibility issue with R12 o-rings or if they just wear out over time but for $5.99 it isn't worth the hassle. http://jeepair.com/o-ring-kits.html?model=38&year=57

again, HTH
Todd
 
And to answer your question on serpentine vs. parallel flow, the pics below give the best visual answer:

Serpentine flow: notice how the lines on each end have a loop. This means that the gas flows from the top port to the bottom in an extended "S" shape. This indicates that it is a "serpentine" flow.
http://www.omix-ada.com/ac-condenser-4-0l-87-96-jeep-cherokee-xj.html

Parallel flow: notice how there are no loops? In this design, the gas enters the condenser and can flow through all of the fins at the same time (i.e parallel). In reality, the gas takes the path of least resistance but the end result is lower pressure.
http://www.discountbodyparts.com/ca...=g&c2cid=6c6d9b7a-7795-4a50-9992-6c090fcacbd0

Since the OEM design was serpentine, most of the aftermarket parts for an XJ will also be serpentine. Rock Auto used to have a version that was parallel flow (which is the one I bought) but I don't see it on their site anymore. The Jeep Air version is "universal" but means you may need to modify the mounts a bit to make it work.

Let me know if you would like me to try to find the original receipt for the one I bought to see if you can match up the part numbers.

Todd
 
Todd

Many thanks for that additional info, which certainly does give me a very comprehensive picture..

I'm happy to stick with the existing '93 expansion valve if it doesn't have to be replaced in order to work with R134a. The a/c certainly doesn't have to work as hard in Scotland as it would in a Texas summer (or as mine originally did in the heat of the Gulf), so maximum coldness isn't critical.

I was aiming to get the system properly flushed but to retain the existing hoses (and thus the current fittings to drier/condenser etc), and just adapt/replace the connections used for filling/testing so that they are clearly appropriate for R134a.

Which means that basically I need to have the whole system thoroughly flushed out, and to replace the drier (of course), the condenser (because the original has a hole), and the connectors, O-rings and oil. The tech guy whom I rely on to fill and service the a/cs in the Jeep and my other cars is very professional: if I get the parts he will make sure the installation is proper.

Which only leaves the issue of which condenser. While I now fully understand the difference between serp and parallel, to be honest the idea of having to mess with a new 'universal' condenser and fabricate new mounts doesn't greatly appeal. If my experience with the radiator replacement is anything to go by, it will be tedious enough to get the old one out and a new one in with standard OEM fittings.

In browsing possible sources it is surprising how many suppliers don't make clear whether the condensers they supply are serp or parallel. I guess most stock OEM aftermarket replacements of whatever brand are very likely the serp configuration.

I'd be quite keen - if possible - to get a parallel-flow one (like the one you got and which Rock Auto used to list) that is an exact drop-in replacement with the right mountings and connections. If you can unearth any clues like manufacturer or part number, that would be really useful. If not, I think I will probably look for a serp replacement with the right mountings, and put up with some loss of efficiency.
 
I found the electronic invoice for the condenser. The pics on most website don't look the same but this one looks exactly like mine:

http://www.carid.com/spectra-premium/a-c-condenser-mpn-7-4173.html

note the vertical tubes on the left and right? each of the cross tubes connects into both of these creating the "parallel flow".

I suspect that if you ensure to order the "Spectra premium 7-4173" from RockAuto or anyone else, they will ship you the correct one.

Hope this helps!



For what it is worth, I have always had good luck with Summit Racing http://www.summitracing.com/parts/sgt-7-4173


 
Last edited:
Latest update - for Todd and anyone else who might be following this thread.

I ordered the Spectra condenser 7-4173 from a US supplier on that well known auction site (cheaper than any other source....) and it has just arrived safely - shipped and tracked internationally. And it is definitely a parallel-flow condenser, which is good. So many thanks to Todd for the detailed advice.

I have the receiver/drier too. What I should have done was order the two hoses (lines, pipes) that connect to the condenser as well. I haven't yet dismantled the existing system, and most of it is OK. But the metal parts of those two pipes, which connect into the condenser behind the grille, look a bit corroded. So if I am replacing the condenser, and the receiver/drier, it does make sense to put in new hoses too just to be on the safe side.

Looks as if the Jeep OEM part nos are 5600 4350 and 5600 4839. But it seems the Four Seasons equivalents (p/n 56278 and 56279) are more widely available.

If those part numbers are correct, I shall now have to see if I can source and order those two hoses. These tasks are never simple!
 
Re: Changing a/c from R12 to R134a on 93 XJ - the hoses!

The a/c conversion story on my 1993 XJ 4.0 continues.... and I haven't even started the actual work yet!

I'm trying to order and assemble all the necessary parts first. So far I have

i) new receiver/drier. Easy: they are available from various manufacturers/suppliers. I got a Four Seasons 33560.

ii) new condenser. Thanks to tjmotter's help and advice, I got a Spectra 7-4173, which is a parallel flow unit.

I still need iii) new hoses.

On this I need help, and I'd welcome advice from anyone with experience. I was not planning to replace ALL hoses. But I want to replace the two which connect to or from the condenser. Both have metal-tube sections and flexible sections. On both of my originals, the metal-tubing that runs up (or down) at the LH side of the condenser, to the connections, is a bit corroded. So it makes sense to replace them.

Now here's the challenge. Depending on year-model, there seem to be different part numbers. I need to make sure I order the right parts (and as I'm in UK and have to order from the US, I can't just go down to the corner store with the old ones and ask for new ones that match!).

According to my XJ official parts manual, the two hoses I need are

  • discharge line/hose (compressor to condenser) OEM part no # 5600 4350
  • "liquid line" (condenser to receiver/drier) OEM part no # 5600 4839
I have been trying to check equivalent p/n from other suppliers, and it gets very confusing.

For the discharge line, Four Seasons offers two: # 56279, which appears to be for older (R12) systems, and # 56830, which appears to be roughly the same length and shape, but has an R134a connection fitting on the metal pipe at the compressor end. These seem to correspond to JeepAir # 72-5522, and # 72-5521. So far so good. The online images seem to suggest that the metal pipe at the compressor end is a slightly diffeent shape (the older one L-shape, the one with the connector is straighter). But I think either would fit on my 1993 XJ.

For the "liquid line", it's not so simple. Four Seasons lists only one, # 56831, and this is catalogued as being for 1994-96 XJs (though I have seen a comment on one website which says it fits earlier models). Weirdly, JeepAir can offer a liquid line for 1990-91 XJs, # 27-5551, or a liquid line for 1994-96 XJs, # 72-5572 (same shape as the Four Seasons one), but JeepAir say they have "no listing" for a 1993 XJ so can't advise which will fit. The images suggest that there is a difference: while the metal pipe at the condenser-end is the same fairly complex shape in both versions, the metal section at the drier end is quite short and straight on the 1990-91 part and it's longer, and an S-shape, on the 94-96 part.

The original liquid line fitted into my 93 Jeep appears to have the S-shape at the drier end. But it would be good to have some expert confirmation that the liquid line listed as fitting the 94-96 XJs would be the right replacement for the one in my 93 vehicle. I would hate to order one and only find on delivery that it did not fit!
 
Ask around for somebody that can make custom AC hoses. Its not a black art, just have to find the guy that knows how to look up the fittings in the catalog, can cut hose to length, and has a crimper. Pretty simple just hard to find that guy sometimes
 
Re: Changing a/c from R12 to R134a on 93 XJ - the hoses!

You may want to call Jeep Air, they should be able to confirm since I am far from being an expert.

Having said this, from my experience converting the '90 to '95, the connectors turned out to be the same so it didn't matter too much. The biggest difference I noticed was that on the '90, the coolant overflow tank was placed in a different position (attached to the firewall) so the hose routing had to be a little different.

My '93 used R12 but as you saw earlier in this thread, Chrysler transitioned to R134 during this model year. This may explain why you can't find a listing since no manufacturer would be certain which version of the '93 you had. From my experience with my '93, the AC routing was the same as a '95 so my recommendation would be to go with the 72-5572 part.

As further background, your model year is very different from a '90/'91 in a couple of key ways: 1) a '93 computer is located on the drivers side next to the air box. On a '90/'91, it is under the dash. 2) (the big one) is that the cooling system on a '90/'91 was a "closed" design which meant that it doesn't have the traditional pressure cap on the rad for filling. Instead, they ran the pressure hoses back to the firewall (under the passengers side hinge) and used a heavier bottle/plastic cap to maintain pressure (and they SUCK). Also, instead of putting the fusebox behind the battery (like yours), they placed a small relay center there which was easy (and safe) to route the AC hoses on top of. On yours, the overflow bottle should be located on the bracket that houses the fuse box and since you would need access to this fuse box, they had to route the AC lines differently.

Net net, I suspect that you will have routing issues with the '90-'91 hose but that the '94-'95 hose should fit perfectly. The connectors should be the same.

HTH
Todd

br1anstorm said:
The a/c conversion story on my 1993 XJ 4.0 continues.... and I haven't even started the actual work yet!

I'm trying to order and assemble all the necessary parts first. So far I have

i) new receiver/drier. Easy: they are available from various manufacturers/suppliers. I got a Four Seasons 33560.

ii) new condenser. Thanks to tjmotter's help and advice, I got a Spectra 7-4173, which is a parallel flow unit.

I still need iii) new hoses.

On this I need help, and I'd welcome advice from anyone with experience. I was not planning to replace ALL hoses. But I want to replace the two which connect to or from the condenser. Both have metal-tube sections and flexible sections. On both of my originals, the metal-tubing that runs up (or down) at the LH side of the condenser, to the connections, is a bit corroded. So it makes sense to replace them.

Now here's the challenge. Depending on year-model, there seem to be different part numbers. I need to make sure I order the right parts (and as I'm in UK and have to order from the US, I can't just go down to the corner store with the old ones and ask for new ones that match!).

According to my XJ official parts manual, the two hoses I need are

  • discharge line/hose (compressor to condenser) OEM part no # 5600 4350
  • "liquid line" (condenser to receiver/drier) OEM part no # 5600 4839
I have been trying to check equivalent p/n from other suppliers, and it gets very confusing.

For the discharge line, Four Seasons offers two: # 56279, which appears to be for older (R12) systems, and # 56830, which appears to be roughly the same length and shape, but has an R134a connection fitting on the metal pipe at the compressor end. These seem to correspond to JeepAir # 72-5522, and # 72-5521. So far so good. The online images seem to suggest that the metal pipe at the compressor end is a slightly diffeent shape (the older one L-shape, the one with the connector is straighter). But I think either would fit on my 1993 XJ.

For the "liquid line", it's not so simple. Four Seasons lists only one, # 56831, and this is catalogued as being for 1994-96 XJs (though I have seen a comment on one website which says it fits earlier models). Weirdly, JeepAir can offer a liquid line for 1990-91 XJs, # 27-5551, or a liquid line for 1994-96 XJs, # 72-5572 (same shape as the Four Seasons one), but JeepAir say they have "no listing" for a 1993 XJ so can't advise which will fit. The images suggest that there is a difference: while the metal pipe at the condenser-end is the same fairly complex shape in both versions, the metal section at the drier end is quite short and straight on the 1990-91 part and it's longer, and an S-shape, on the 94-96 part.

The original liquid line fitted into my 93 Jeep appears to have the S-shape at the drier end. But it would be good to have some expert confirmation that the liquid line listed as fitting the 94-96 XJs would be the right replacement for the one in my 93 vehicle. I would hate to order one and only find on delivery that it did not fit!
Click to expand...
 
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