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Hey does anyone have engine bay pics of their 91-92 ac system? Mine was removed and I'm trying to gather all the parts, as many new as possible. I can get everything from an 89 MJ but I don't know that it will all be compatible. Can I get parts from a 96 so I can have 134a?  Thanks. 

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The '89 parts are not compatible. You may be able to make them fit, but it's really probably not worth the effort. The compressor and compressor mounting is different, and I'm not sure if you can simply swap out the compressor brackets to fix that. The earlier system has a smaller compressor and theoretically less cooling power as a result.

 

The '96 parts pretty much just bolt on. It's the same compressor as your '91 would have come with, just with a different cylinder head and line connections. Everything except the line from the expansion valve to the receiver-drier is available new, and pretty cheap too. The only permanent modification you need to do this is to replace the connector on the high-low safety switch on the drier. Just snip the plug off of a '95 or '96 XJ. HOWEVER - doing this will make oil filter changes more difficult. The later line configuration places two of them right where the oil filter is on your truck right now. Later engines had the oil filter turned back towards the rear of the truck to clear these lines.

 

BUT

 

My advice - perform the '96 swap at your own risk. One member @schardeinhas had good luck with the swap. I, on the other hand, am not satisfied with my '96 A/C swap and will be going back to the original '91 setup at some point in the future. It works great, but I am having trouble with compressor slugging after shutting the truck off and getting back in after about 10 minutes. That's a really bad problem, and could turn the compressor into a glitter bomb in a hurry. I'm just going to put it back to stock.

 

I think if I were in your position, I'd just stick with the '91 way. The only tough things to find will be the service valves on the compressor, and even those shouldn't be too hard to find. Use the parallel flow condenser from APDI with all-1991 parts, and you should be good to go. My sources aren't clear on what lines you can't get new, so that leaves two and you still might be able to get those. I'd need to do some more careful looking. You can definitely get the suction and discharge lines new. If you can't get a hose new, you can always find an old one and have a hose shop make you a new copy. I wouldn't bother with flushing something 30 years old that wasn't made to work with R-134a in the first place. Just make sure they use barrier hose, and keep in mind that you will not have standard Schrader valves with the 1991 system. The service valves on the 1991 system are manual! If you take your gauges off and don't close the service valves, the inside stuff will get outside! Don't ask how I know.

 

Factory charge weight was 38 oz for the '91 system, so with R-134a you want approximately 30 oz.

 

If you didn't know, you can get parts from 1991, 1992, and 1993 Cherokees as well.

 

The condenser I recommend is the APDI 7014173. The OE-replacement condenser may suffer with R-134a as it was designed for more efficient R-12. That part number fits 87-96 MJ and XJ with 4.0L. The company that makes it only lists it for Comanches.

 

These trucks used Sanden compressors, which in my experience make some amount of noise and vibration inside the cab when the A/C is running. Don't worry about it too much, I've tried almost everything I can think of to get rid of it.

 

I think that's most of it. Hopefully this is actually useful and not just incomprehensible word salad.

 

 

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I installed new '95 XJ components many years back in my 92 MJ. Complete bolt-in and "benefit" of r134 (here in CA no options on that). No issues.

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In 2017 I bought all the tools, supplies, and parts to repair the AC systems on my 91 XJ, 91 MJ, and 01 Silverado.  I converted the XJ and MJ to 96 parts to use the new refrigerant.  I don't remember all the details, I but remember having to get a little creative with mounting the new condenser.  And swapping the plug on the dryer as Jeremy mentioned.  

 

It does make changing the engine oil filter an issue.  I have converted the XJ to a rear facing filter adapter.  The MJ will get the same eventually.

 

I have to say the Silverado turned out great- AC worked so well you didn't want to run it full cold.  The XJ and the MJ on the other hand, work OK.  Barely OK.  That's with new everything except the one line that isn't available new, and the old evaporator, which I flushed out.

 

Here is a pic of the MJ- not the greatest pic, I think I was documenting the cruise control install.

IMG_4025.jpg

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