Another AC Question

A buddy of mine has an XJ for parts, I forget what year it it is but it has a 3rd tail-light and a soundbar in the rear and a High Output Engine. I think it's a 94 or newer, possibly 93 or newer so would it have an R134 AC System?

I have a 90 XJ with a RE4.0 and an R12 AC system. The newer XJ has a fully working AC system, my XJ has a hole in one of the AC lines so what parts do I need off the newer XJ to convert mine over? Will the piece inside of the dash bolt up to the newer style lines? I'm talking about switching everything from the newer one into mine except for maybe the compressor, and definately not the piece in the dash/heater box. Will it work?

It should have some sticker under the hood (hopefully still intact) advising you that its a R-134a system. You can get new service fittings at autopart stores but you need to evacuate and replace the freon and oil as well as the filter-drier. If you are getting free (or cheap) parts I'd take the compressor as well, its built to handle the higher R-134a operating pressures. And you have leaks so I would just swap the whole package: compressor, hoses, filter-drier, accumulator leaving the original evaporator / condensor cores. I'm not sure if its going to fit without needing custom hoses or fittings.

If your going to swap your R-12 System for a R-134, your most likely going to have to swap everything.

The existing evaporator would probably work fine, if the lines bolt up. I don't know, but I suspect it won't.

Your going to want to swap compressors, R-134a operates at different pressures then R-12, a compressore designed for R-134a is going to give you better performance and reliability than a converted R-12 compressor. As well, you have to use a different oil with R-134a and the oils are not compatible with each other, so the old R-12 compressor is going to have the R-12 oil still in it (its almost impossible to get all the oil out of the compressor) and it will contaminate the R-134a oil.

If you have an R-134a system to swap in, why not use the whole thing. I can see trying to save some effort by re-using the existing evaporator, but the connections have to be compatible. The pressures in an AC system are way to high for improvised connections, you have to have connections that are designed for those pressures.

I dunno if I wanna rip the whole dash out just to replace the one part.

BTW- on an XJ with a 2.8L V-6 would everything bolt up? The guy with the newer XJ also has an older one...

I know I'm not much help here, cause I don't know the details, nor do I think will anyone else.

Perhaps your best luck will be to find the parts catalogs for both years of vehicles and sort thru them for the part numbers of the different pieces. Or a junkyard interchange book. You can do some cross-referencing to find if the same part was used over the years.

Otherwise, your probably going to have to experiment and find out. Take the parts off one and see if they fit the other.

Hopefully the lines for the evaporator will connect to your existing evaporator, if they do, you can get away with using the existing evaporator. If not, your going to have to swap evaporators as well, like I said, the pressure involved are too great to improvise some sort of adapter for the lines, you want the OEM connections.

You might want to just look into retrofitting your system to R-134a instead of doing the swap, it would probably work better than trying to do a hybrid of both systems all rigged together.

If it's a R134 system you would need everything and the worst problem would be control. The R134 system is controlled by the ECU.

I believe when Jeep went to R-134a they switched to using an accumulator rather than a receiver drier as well. I know on my 90 I have a receiver drier but on my bro's 01,he has an accumulator. I don't think you're going to be able to put a complete R-134a system into your XJ sucessfully. I've converted my system over changing out just the expansion valve, receiver drier, and using a remanned compressor which will accept either refridgerant and it blows out really damn cold. There are going to be varying answers with this but I was fine just doing the conversion.

i had r-12 on my 94xj 4.0L

i converted from r-12 to r134a in my 90 jeep and darn that thing gets cold.
it was funny though i was at auto zone the other day and the where confused to as what the valves where for on the compressor. i almost walked over ro help.

r134 couplings are quick type fittings like a large air hose. R12 fittings are threaded couplings like a tire stem.
The are some new refrigerants out like freeze 12 that's a direct replacement for r12

I'm in the process of converting my 90 to R134a. Use Ester oil if you do as it is the most compatible with both. The original mineral oil in the R12 system is supposed to gel with R134a and kill the compressor if left in.
Try to find all the leaks first.
Drain out the mineral oil from the compressor and reciever-dryer - measure it as you do - and replace with a like amount of the new oil. Using a new r/dryer is a good thing after 16 years as you're actually replacing the dessicant. Water in the system will corrode the lines and compressor, and probably caused the problem to begin with.
Flushing the lines won't hurt either.

In counterpoint, the auto school my supervisor attended had 10 cars from various auto lots volunteered for a changeover. They recovered the R12 and pumped in R134a, nothing more. Nine worked just fine, the tenth had a compressor failure. I don't know how many were pre 134 late models - they were semi-ready by the factory the year or two before the deadline - but I think the results are comparable to what I see across the counter. The worst case scenario needs all the bells and whistles, but which one is it?

My 95 cherokee sport has the rear sound bar as you described, and is running R 134.